What is the ideal HERMS coil length? Theory and experiments


When we started selling HERMS coils 2 years ago, we made our 40cm coil 15 meters (50 feet) long. The 30cm coil was 11.5m long. Why? That’s what most home brewers were doing.

But we recently started to suspect that such a long coil is not optimal. Sure, a longer coil will give you a higher output temperature, but it will also have more friction, reducing your flow. Each extra loop of the coil will cause a small temperature rise, but with diminishing returns for each extra loop. But each extra loop will also add a additional amount of friction.
The amount of heat transferred to the mash tun depends on both the achieved input-to-output temperature difference and the flow rate, so there is a length that results in the maximum heat transfer. We set up an experiment to estimate what this length would be.

Below, you see a photo of the HLT we used for testing. It has a 40cm HERMS coil, made of stainless steel tubing (0.5mm wall thickness and 11mm inner diameter). The element is a 3500W element. Elco dry fired it once, which is why it turned black. It still works fine though. On the bottom right, you can see the temperature sensor and the dry fire protection which was installed after ruining the element.


Based on our experiments, an 8 meter coil maximizes the heat transfer. This of course depends on many factors, like the coil material, your pump pressure and other losses in the system. We also found some other simple optimizations you can apply to your brewing setup and came up with a complete new coil design for big kettle setups.

HLT with BrewPi HERMS coil

Hot Liquor Tun setup with whirlpool, heating element and HERMS coil.

Heat transfer as function of flow and temperature difference

The amount of heat that is transferred every second (power in Watts) can be calculated by multiplying the volume that is transferred, the temperature difference between coil input and output and the specific heat capacity of water. In formula form:

\[ P = V \cdot \Delta T \cdot c_p\]

So to heat up your mash as quickly as possible, you want to maximize this equation.

Experiment setup

To find the ideal length, we needed to determine 2 things:

1. How much does each loop of the coil contribute to temperature rise?

It costs a lot of work and money to make multiple coils of different lengths, so we came up with an alternative: we decreased the amount of water in the HLT, submerging only a fraction of the coil. We assumed that only the submerged loops are contributing to the output temperature significantly.

Timelapse of HLT water levels

Hot Liquor Tun water levels for each successive test.

2. How much friction does each loop add?

This one is a bit harder to test, so we took a more theoretical approach. We measured the flow rate twice, once bypassing the entire coil and once pumping through the coil. From the difference in flow rate, we calculated the friction factor of the entire coil. We used that value to calculate the friction that shorter coils would have.

The experiments

Flow rate

We measured the flow simply by filling a bucket with the return tube of the HLT, timing it and weighing the amount of water. The results were:

  • 5.8 liters per minute with the coil
  • 9.8 liters per minute without the coil.

Switching between with and without coil could be done by simply toggling a valve. Because it is fully automated Elco’s system has a lot of tubing, meaning there will be a lot more friction. In simpler setups with less tubing you will get higher flow. We correct for that later.

Flow calculations

There’s a lot of math in this section, feel free to skip it. What we did is measure the flow with and without the coil and from the difference we calculated the friction of the coil.


To calculate  (flow velocity in meters per second) we used the Bernoulli formula.

Bernoulli formula:

\[(p_{1} + \frac{1}{2}\rho v_{1}^{2} + \rho g z_{1})-(p_{2} + \frac{1}{2}\rho v_{2}^{2} + \rho g z_{2})=f \frac{1}{2} \frac{L}{d} \rho v^{2} + K \frac{1}{2} \rho v^{2}\]

Without the coil, this formula simplifies to:

\[p_{pump}= K \frac{1}{2} \rho v^{2}\]

This allows us to calculate K, our dimensionless loss factor for everything except the coil.

\[K = \frac{2 \cdot p_{pump}}{\rho v^{2}}\]
\Big[ \frac{kg}{m^{3}} \Big]

Our pump pressure is known from manufacturer (4.5m head), and the density of water  at 60°C is 980 


Now that we have a good estimation for the loss factor K, the friction factor  of the the coil can be determined from the difference in flow velocity. The pressure of the pump does not change, so we can solve the following formula.

\[p_{pump} = f \frac{1}{2} \frac{L}{d} \rho v_{1}^{2} + K \frac{1}{2} \rho v_{1}^{2} = K \frac{1}{2} \rho v_{2}^{2}\]
\[f=K \cdot \frac{d}{L} \frac{v_{2}^{2}-v_{1}^{2}}{v_{1}^{2}}\]

Now that the friction factor of the coil is calculated it can be used to estimate the speed of the wort for different coil lengths.

\[v = \sqrt{\frac{2 \cdot p_{pump}}{\rho (f \frac{L}{d}+K)}}\]

We got a resulting friction factor of 0.0407, giving the following flow curves for a K of 30.

Pump flow and speed for Elco's system

Volume flow and velocity for Elco’s system for various coil lengths

Elco’s system has a lot of tubing and valves, because it is fully automated. You can see the schematic of the entire system here:

Elco’s brewery with automated valves, interactive demo

To mimic our experiment in this setup, select the mash recirculation step. By toggling valve v6 we could bypass the coil.

And here are some photos of the setup:

Temperature sensors on coil

With the temperature sensors inline with the coil, we could measure the coil in and output temperature.

Elco's setup water pump cluster

This cluster pumps water from the HLT or water input to the HLT (top valve v1) or router cluster (bottom valve v2)

Elco's setup wort pump cluster

This cluster gets water from the MT (top left v9) or BK (bottom left v10) and pumps it to the router cluster via the CFC (bottom right v12) and bypassing the CFC (top right v11) or drain (middle v13)

Elco's setup router cluster

This router cluster gets clean water from the left or wort from the right. The connections at the bottom are MT in (v3) coil out (v5) coil in (v7) or BK in (v8). By toggling v6, in between v5 and v7, we could bypass the HERMS coil.

This shows the water input on the right, with a valve for the water pump cluster and the CFC and a ‘to fermenter’ output on the left.

As you can see from the photos above, Elco’s setup has a lot of tubing and valves. This results in a lot of friction in the system, and therefore a high K factor. We think a K of 15 will be more representative of a typical homebrew setup.

A loss factor K of 15 will result in the following flow charts.

Pump flow curve using f value of 0.0407 and K value of 15

Volume flow and velocity for a more typical system with less tubing and valves

Coil efficiency vs. length

To measure the temperature distribution through the coil, we measured the output temperature of the coil for different water levels in the HLT. We measured:

  • 1.5 loops submerged
  • 3.5 loops submerged
  • 5.5 loops submerged
  • 7.5 loops submerged
  • 9.5 loops submerged
  • 11.5 loops submerged

For each water level in the HLT we recirculated the mash tun water through the HERMS coil to go from 55°C to 65°C, while trying to keep the HLT at 70 degrees. We measured:

  • Coil in temperature
  • Coil out temperature
  • Mash tun in temperature
  • Mash tun out temperature
  • HLT temperature

Here you can see the measurements form having 11.5 loops submerged:

brewpi data test 2 using 11.5 meter submerged coil

Raw data as recorded by the BrewPi brewing controller

For each measurement we started the HLT at 70 degrees and the MT at 55. We then closed valve v6 to switch from bypassing the coil to pumping through the coil.
After each run, we would discard some water from the MT, add some fresh cold water and make sure it was back at 55 degrees with the same volume for the next test.


We measured the input temperature difference (HLT – coil in) and the output temperature difference (coil out – coil in), so for each point in time we can calculate the efficiency  of the submerged section:

\[\eta = 1 - \frac{\Delta T_{out}}{\Delta T_{in}}= 1- \frac{coil_{out}-coil_{in}}{HLT - coil_{in}}\]

Each experiment would give us a set of points for the efficiency for a certain coil length. You can see these as a set of dots in the chart below. We only used the points for which the input temperature difference was between 4 and 8 degrees, which is the typical use case.

efficiency plot with temperature difference legend

Efficiency of a HERMS coil for different coil lengths

\eta = \eta_{max} \cdot (1 - e^\frac{-t}{\tau})

We fitted a curve through these points, with the formula  where  is a time constant based on the lumped thermal capacity model. Our fitted curve has a time constant of 4.5,  of 0.79, and  is the time spent in the submerged part of the coil, which can be calculated form the flow velocity.


Now we can use this formula to calculate the coil output temperature for different lengths by calculating the time spent in coil () first and entering it in this formula.

Heat transfer analysis based on our experiments

Now that we have determined how coil length changes flow rate and efficiency, we can use the formulas to calculate how much heat will be transferred for each coil length and temperature difference. As you can see in the chart below, the curves are as expected: making the coil longer increases the efficiency, but after a certain point the loss in flow rate cancels out the higher output temperature.

Power curve with respect to coil length

Power transferred to mash with different temperature differences between HLT and mash temperature

We have found 8.2 meters (dotted line) to be the most efficient length. The graph above is calculated with K = 15.

From the graph, you can also see that if your temperature difference is small, the power with which you heat your mash tun is low.

Recommendations for your own HERMS setup

During our experiments, we also found some quick improvements you can use to make your own mash go faster.

Exit the coil at the bottom

We did our experiments twice, once with the wort entering the coil at the top and leaving on the bottom and once the other way around. It turns out that having the wort in the HLT coil flow from top to bottom is more efficient that from bottom to top. This is because the water in the HLT is hotter closer to the element, even when there’s a whirlpool in the HLT. Our experiments found a 12% increase in efficiency when wort flowed from top to bottom.

coil efficiency comparison flow direction HERMS coil

Two efficiency curves with changing flow direction within HERMS coil

Keep the temperature difference high

V \cdot \Delta T \cdot C

Because the heat transferred per second is , to reach your mash temperature quickly, you will want to keep the temperature difference high. However, you don’t want to overshoot your target temperature. If you have a lot of water in the HLT, your HLT will continue to heat your mash if you keep pumping, even after you stop heating your HLT. All the heat that you put into your HLT will eventually distribute between your HLT and MT. A small example:

Let’s say you have 40L in your HLT and 40L in your mash tun. Your target temperature is 65 degrees and your mash is currently at 63 degrees. How high can you set your HLT to not overshoot? If you assume there are no temperature losses, the answer is 67 degrees. The equilibrium situation is that the HLT loses 2 degrees to the MT and both end up at 65:

\[ \frac{63 \cdot 40 + 67 \cdot 40}{40 + 40} = 65\]

Now let’s take another look with only 10L in the HLT, still 40L in the mash tun. Now you can heat up the HLT to 73:

\[ \frac{63 \cdot 40 + 73 \cdot 10}{40 + 10} = 65\]
\frac{\textrm{HLT volume}}{\textrm{mash volume}}

With a 4 times smaller HLT, you can heat your mash 4 times quicker without overshooting. If you use BrewPi for mashing, you would set your Kp for the PID that manages the HLT setpoint to the  to automatically manage the HLT setpoint.

So our recommendation is:

  • You can use a big kettle for your HLT, but don’t fill it up fully until you are heating your sparge water.
  • Mount your HLT coil as close to the bottom as possible
  • Use a low and wide HERMS coil if possible.

Whirlpool or stir your HLT

We measured the temperature response with and without recirculating our HLT water. This makes a big difference in the temperature exchange, as you can see from the graph below. Without stirring your HLT, the water around the coil will be a bit cooler, decreasing the output temperature.

Whirlpool vs no whirlpool in the HLT

Whirlpool vs. no whirlpool in the HLT

Our new HERMS coils

We changed the HERMS coils we sell based on these experiments.

Our 30cm HERMS coil has been shorted from 12 windings to 8 windings. It is now 7.5m long instead of 11.3m.

Our new 30cm HERMS coil

We are going to discontinue our 40cm HERMS coil, which was 15m long. The longer coil does not help with heat transfer. We have come up with an alternative though!
For big kettles, we have made a prototype of an entirely new design, suitable for big kettles and high power elements.

To maximize the heat transfer, we want to:

  • Maximize the time the wort is in the coil, to increase the efficiency
  • Reduce the friction of the coil

The only way to do both at once, is to increase the diameter of the coil. We chose to do this by having 3 coils in parallel, ending in one 1 inch fitting.

This design will have:

  • A lower velocity and therefore less friction, because the flow velocity per coil is lower and the coil is shorter
  • A lot of surface area
  • A very low height, making it possible to have only very little water in the HLT to be able to work with bigger temperature differences.

The 30 cm HERMS coils are back in stock now. For the new 3-way parallel super awesome high flow coil, we only made a few prototypes. They’ll be available in about 4 weeks.

Source and comments

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Can you convert html, css and javascript into a exe?

  • Electron, by GitHub. Lets you build cross-platform Windows, MacOS, and Ubuntu applications from HTML/JavaScript/CSS. It works by embedding them into a Chromium build alongside with Node.js. Many applications such as Slack and Visual Studio code are built with Electron.
  • Cordova, by the Apache Foundation. Targets Android, iOS, and Windows from HTML/JavaScript/CSS. It works by embedding them into a WebView (or whatever is the equivalent on the target platform).
  • Proton Native. Works with React Native components and does not use Electron (see above), which makes generated apps therefore more “lightweight” than the ones generated by Electron. Uses libui under the hood.
  • Yes, there is a program HTML Compiler that allows you to convert an entire HTML application (using CSS, JavaScript, Images and more) into a standalone Windows application.
  • There is also ExeOutput for PHP that lets you create applications in native format for Windows with PHP, JavaScript and HTML. Convert PHP scripts, websites, JavaScript, HTML, databases into stand-alone apps for Windows (single EXE files) that do not require a Web server nor PHP distribution.

For window apps

If you need something to present you a window environment and a webserver emulation, choose ZZEE or ExeOutput, these are decent tools, maybe ZZEE is a bit outdated regarding the PHP version. So for “HTML, CSS and Javascript”, the answer is clearly something like this.

For console apps

If you only need a tool to run in the background or from command line, here’s my pet project called RapidEXE – it’s quite simple to use, somewhat extendable and features PHP 7 out of the box. Also, it’s free and always will be. But since there’s no browser involved, technically this is not solution for HTML/CSS/JS; just something very similar, like using web-related languages to create EXE files.

A real compiler: JSC

If you want (something-like-)javascript to be compiled to a standalone EXE, give a chance to JSC, it’s there in your Windows, you just probably never met before. JSC gives you extremely small executables (because of the .NET already built into Windows itself) and they have full power of .NET so you can do pretty much anything you want. Flipside: apart from the syntax being familiar, not a lot will remind you of Javascript, you have to learn a lot of new practices to get along.

A bonus track: “chrome –app” and RAR

If you can live with a dependency such as Chrome, you can do a nasty but working solution: RAR can create a self-extracting EXE for you and run a command after extraction (!!), so you can pack up a little micro-universe of HTML/CSS/JS files; then you can call Chrome with “–app=something.html” that will give you a plain window with a browser environment and your HTML file in it. I know this is not a compiler; however, it’s a way to create an EXE that is self-contained and gives the user a web-liek experience in an application-like window. Sure, Javascript will be a bit limited because you’re running in a local file, not a proper website, but it’s not that painful. One lovely thing about this technique is that Chrome will remember the position and size of your window so it will pretty much feel like an application.

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How to Prevent DMS in Beer

A  Look at Studies and Experimental Brew with Tested Results

The past few weeks I have casually been combing through over 20 academic studies on DMS, a topic in brewing that has benefited from a surprisingly vast amount of research and experimentation. Of most interest to me, other than understanding the various aspects of the brewing process that can prevent or lead to DMS in beer, is to determine if DMS is even something brewers need to worry about anymore. If so, how specifically can DMS shape or alter hop aromatics and flavor. The move to higher malt modification has generally created malts that are less susceptible to creating DMS and likely a reason for DMS weighing less on brewers minds. However, as one of the studies detailed below shows, in tested commercial example of ales, DMS was found in amounts above taste thresholds and in comparable amounts as the lagers tested. Could it be that DMS even at low but detectable levels is playing a greater role in shaping the overall flavor profile of beer?

In this post, I first outline the relevant tested information on DMS creation and prevention throughout the brewing process outlined in the academic literature reviewed.  I then applied the information to brew an experimental beer doing nearly everything wrong to see if any DMS was actually created. After all, if the beer ends up being fine, despite going against traditional anti-DMS protocol, then this would all be a non-issue anyways. To go further than just taste the poorly brewed beer, I sent three samples to Oregon State University where levels of DMS were tested. The results of the test and tasting notes, including the effect DMS had on hop aroma and flavor are outlined below the research.

What is DMS?

Dimethyl sulfide (DMS) is a sulfur compound that is typically considered an off-flavor in beer at high concentrations and is introduced into beer from the thermal decomposition (wort heating) of S-methylmethionine (SMM) produced in the embryo of barley during germination.1 SMM finds its way into wort because it is readily dissolved from malt at all mashing temperatures. During fermentation, yeast can also reduce another precursor called dimethyl sulfoxide (DMSO), that can turn into DMS in the finished beer. This reaction is by a yeast enzyme called DMSO reductase.2 The extent of this conversion of DMSO is dependent upon the particular year strain employed.3DMS can also arise from wort infected with spoilage organisms.4


DMS is typically described as having an aroma of cooked or creamed corn; however, the literature goes further with descriptors such as sauerkraut-like, black olive, canned corn, cabbage, rotten onions, and blackcurrant buds. DMS is a major contributor to the aroma other beverages and foods including many vegetables like asparagus where DMS is the “dominating character impact compound” and is generally described as having odor sensations of germ-like, mushroom-like, and nutty. 5 White wines, milk, rum, and numerous cooked vegetables are also documented for having a DMS aroma and flavor component.6

Prevalence in Commercial Beers

Most brewers probably don’t think their beer (especially ales) contains detectable levels of DMS, however, an interesting study of thirteen commercially available beers were tested with surprising results. Seven domestic ales, two domestic lagers, two imported lagers, and two non-alcoholic lagers were among the beers tested and found that DMS was at or above flavor thresholds (30-60 µg/L)7 in all but one of the beers, which shows that DMS was contributing to the flavor profile of the beers. Surprisingly, DMS levels in the ales were comparable with the lagers, which are known for producing higher amounts.8 The flavor threshold for DMS is relatively low at 30 µg/L, so it doesn’t take much to contribute to the flavor of a beer.9


Most of the DMS in beer produced from the SMM precursor is lost (evaporated) during the boiling process. Specifically, it was determined that the half-life of SMM at boiling point is 37 minutes, which means that half of the SMM is evaporated from the boil pot at 37 minutes. A boil of 90 minutes removes approximately three quarters of the DMS and most of the SMM is lost during a 120 minute boil. This half-life of SMM is increased when the temperature is decreased. For example, if wort is heated but not boiled (like a no-boil berliner weisse) to around 190°F, it would have to be held at this temperature for approximately 130 minutes to evaporate half of the SMM precursor.10 The physical location of the brewery can alter the evaporation of SMM because wort boils at lower temperatures at increased elevations, which would result in much less conversion of SMM to DMS in the boil.11

The vigor of a boil also contributes to final DMS levels in beer. One study looked at the power input of a boil and the impact on DMS. The authors found that the when the power input used for boiling increased, the levels of DMS decreased (in a DMS water solution). During a 60 minute boil almost no DMS was detected at 1,500 watts where at 1,000 watts approximately 175 ppb of DMS was detected. At 500 watts, about 300 ppb of DMS was detected. 12 A small electric stove uses about 1,500 watts per hour while it heats on medium or high.13


During hot stands where the wort remains at hot temperatures after the boil (now typically called hopstands) any remaining SMM in the wort that wasn’t evaporated during the boil will continue to hydrolyse and more free DMS will be formed. One study extended a hot wort stand by one hour and found higher DMS concentrations from an average of around 49 µg/L to 104 µg/L in the extended hot stands.14 This means if a short boil time is combined with an extended hop stand, more DMS in the final beer could be formed. Or in the commercial realm, if a long whirlpool is conducted in a well-insulated vessel or long transfer times occur at hot temperatures, this could lead to a continued breakdown of SMM that survived the boil.

Foam During Boil

One of the most recent studies on DMS looked at the role of beer foam during boiling and the impact of the vaporization of DMS from wort. The authors found that the vaporization of DMS was strongly enhanced in the presence of beer foam versus trials where an antifoam agent was used. Although the direct cause of this was not the point of the study, they speculated that one explanation could be that DMS might actually concentrate in the foam and is then stripped from the wort by the rising vapor of the boil.15

Role of Carbon Dioxide

During fermentation, measured levels of DMS are purged via C02 escaping. Specifically, one study found that there is a significant decrease in DMS levels over the course of the first five days or so of vigorous fermentation, with days 1-2 seeing the most dramatic decreases. However, after day five there was a measured increase in DMS in the fermenting beer, which was produced by the yeast from the DMSO precursor. 16 The Miracle study found an increase in overall sulfur volatiles by the yeast after fermentation was completed with just a short contact time with yeast present, finding that prolonged post-fermentation conditioning in primary can lead to more sulfur-containing volatiles. Specifically, DMS increased to 43.4 μg/L with 30-day residence in a keg vs. 32.6 μg/L with only 14-day residence in the keg.

Why would DMS be created after primary fermentation is complete? Gibson found that when nitrogen is present in the wort in excess a constant and low level of DMSO reductase is detectable. Most typical worts have enough assimilable nitrogen for the yeast, however after primary fermentation and attenuation has been achieved the nitrogen levels in the yeast cells become depleted, which can lead to an increase of DMSO and thus DMS.17 To avoid DMS creation after primary fermentation is over, I’m curious if adding a very small amount of yeast nutrient containing nitrogen around day five would be beneficial.

Open/Closed Fermentation

One study looked at the difference of DMS in beers fermented in an open fermentation system (fermenter with a partially opened top) vs. an enclosed conical vessel. They found that DMS in the open topped fermenter contained the amount of DMS anticipated from the potential of the wort, however, the beer fermented in the conical vessel contained more DMS than could be accounted for from the worts potential. The difference was stark with an ale fermentation resulting in only 9 µg/ in the open fermenter and the conical resulted in 57 µg/ at the time of racking.18 Homebrewers could easily mimic this open fermentation by covering the top of the carboy with sanitized tin foil for the first five days or so of vigorous fermentation then replacing the foil with an airlock for the remainder of time in primary.

Fermentation Temperature

A 1980 Journal of the Institute of Brewing looked at both original gravities of wort and the temperature of fermentation and the effects on DMS in beer. The authors found that worts of high gravities create substantially more DMS than worts of low gravities. Specifically, fermentations of a 1.060 wort had over three times more DMS than a 1.033 wort (adjusted with either glucose or fructose to achieve the higher gravity). With respect to fermentation temperature, it was found that as the temperature increased the level of DMS decreased. The maximum DMS level achieved with a ferment at 46°F was five times greater than a ferment conducted at 77°F.19 This is because DMS production by yeast is greater at lower temperatures.

Gravity of Wort

High gravity worts that are increased in fermentables by the use of sucrose (table sugar) may actually see lower levels of DMS in the finished beer. This is because sucrose can lead to increased DMS volatility. A recent study found that a solution consisting of 10% sucrose (in water) saw a remarkable increase in DMS evaporation.20 However, worts are low in sucrose with typical fermentable sugars profiles of maltose (42-47%), maltotriose (11-13%), hexose (7-9%), and sucrose (2-3%).

Unmalted Cereals 

Because barley malt is the main source of SMM, the DMS precursor, the less used in the grist the lower potential for DMS in the finished beer. One way of using less barley is by substituting some of the grist with unmalted cereals, which can also contain DMS precursors, but likely will boil out completely as corn has been shown to do.21 Interestingly, cereals with high gelatinization temperatures, which require boiling prior to usage, may actually have less DMS precursors because this processes breaks down and evaporates DMS, leading to less total DMS precursors in the boil compared to an all malt grist.22

Yeast Storage/Health

The storage of harvested yeast may also play a role in the levels of DMS in beer. A 1985 study examined the DMS levels of beer with yeast stored for 5 days at 34°F under beer (like most homebrewers save yeast) and one stored in water and agitated twice a day and another stored under water receiving constant agitation (via stir bar). Levels of DMS were lower in beers stored unagitated under beer than with agitation. Specifically, the agitated yeast had 25% more DMS in the finished beer which was likely caused by yeast damaged (oxygen toxicity) that may have occurred from stirring resulting in a less vigorous ferment stemming from less healthy yeast pitched.23 This finding is a good reminder to ensure pitching an appropriate amount of healthy yeast, because a healthy vigorous fermentation can aide in controlling DMS Levels.


DMS can also be introduced into beer through hops. At the end of a typical 60 minute boil all of the sulphur volatiles have evaporated, however during late hoping and whirlpool additions three sulfides peak, including DMS, which is then detectable in the wort. Some of this DMS will be reduced during fermentation via C02, but some could survive and stay in the beer until packaging.24

pH Levels

It was found that worts with a high starting pH can lead to greater amounts of DMS in the final beer. The following chart shows test results of wort fermented with with S. cerevisiae NCYC240 at different starting pH levels.25

Initial Wort pHFinal Beer pHFinal DMS (µg/L)

Experimental Brew & Results

I decided to brew a NEIPA to test out the research and to see how potential DMS could influence hop aromatics and flavors. Based on the literature, I took the following actions to potentially encourage DMS production:

I aimed for a mash pH over 5.4 which is slightly higher than most typically try to achieve in pale hoppy beers. I tend to like NEIPAs finishing with a slightly higher pH anyways because it seems to smooth out the finish of the beer (less of a bite) by also requiring less direct bittering by hops because beer can actually taste more bitter as the pH increases even when the iso-alpha-content remains the same.26 To help position myself for a higher finishing pH I generally aim for a higher mash pH of around 5.4-5.5, which according to the pH study above, could actually be slightly increase the final DMS content in the beer, which seems to be strain dependent.

At boiling temperatures the half-life of SMM is 37 minutes, so it seemed like a bad idea (or in this case a good idea) to heat the wort up 212℉ and immediately cut the heat. I proceeded to scoop out any foam that was created from the top of the wort as it heated to discourage DMS evaporation (again based on the study above). Because the beer didn’t reach a roiling boil, the foam creation was considerably less than normal, so there wasn’t much to remove. Rather than chilling the batch at this point, I opted to do a 60 minute hopstand, which should give the SMM remaining in the wort from not being boiled out plenty of time to hydrolyse into DMS.

On day five of fermentation, I dry hopped the beer and then capped the fermenter by sealing the 10 gallon keg the wort was in. Learning that after primary fermentation is largely over the nitrogen levels in the yeast cells can become depleted leading an increase in DMSO by the yeast, should this occur, the sealed keg should trap any DMS trying to escape via C02 (as well as potentially retain the dry hop aromatics).

Click to Expand Recipe Details
DMS Results

As you can see from the results above, the testing showed a total of 177.2 µg/L of DMS. To put the results into context, ales will generally have less than 30 µg/L, but below 100 µg/L, and anything above 100µg/L is when the flavors associated with DMS start to really come through. When I transferred the beer from the fermenting keg (with C02) to the serving keg with the hops, the aroma coming out of the receiving keg lid immediately reminded me of a hoppy no-boil berliner weisse I made a few years ago. During the first couple weeks in the fermenter the berliner had a very strong musty and briney aroma that made me think I screwed something up. Eventually, with extended time in the fermenter (about 30 days total) and further souring, the aroma did seem to fade quite a bit, but not completely make it’s way out of the beer (I actually enjoyed it, thanks to dry hopping). Now being fairly confident after smelling this experimental beer that what I was likely picking up in the no-boil berliner was DMS, I’m not sure if it cleared up a little from the extended time in the fermenter allowing C02 to push some DMS out or if the flavors and aromas from souring eventually dominated. This experimental beer on the other hand didn’t have additional time in the fermenter (plus it was sealed after day five) and the aroma definitely didn’t fade!

At first pour it’s got a lot of what I would cautiously describe as hop aroma, but with a healthy dose of aromatic hops (Citra, Galaxy, and Amarillo) in two separate large additions, it’s not what you would expect at all. The hop aroma is difficult to describe because it’s being altered so much from the DMS. I’ve settled on calling it an overripe and borderline rotten fruit smell, which sounds about as good as it tastes. This fairly strong “hop” flavor quickly fades though and the briney vegetative aroma comes through even more. Having gotten the results back and knowing that DMS is very prevalent the beer, I wouldn’t say the smell reminds me of creamed corn, maybe this is largely from the dry hopping. To me, the smell is much closer to cabbage and sauerkraut, I can even see how you could describe it as asparagus (based on the research) as opposed to corn.

The overall beer itself is questionably drinkable, it still has a great mouthfeel and all of that, but it’s just so strange. There is no question (and this isn’t really a surprise) that DMS in a high concentration is enough to dominate the hop flavor and aroma. I’m now curious how much DMS might influence hop flavor and aroma in smaller concentrations. For example, if a NEIPA is tested for lets say 50 µg/L, how might even this smaller amount alter the aroma of fresh and fruity hops? I’m particularly interested in this question because I have often thought that as hops fade with time, especially in commercial bottles a few months from packaging, they seem to drift from fresh fruity aromatics to more earthy and vegetative aromas (often I think green onion). I’m not saying for sure this is DMS eventually coming through as the hops fade, but this experiment does seem to convince me that it makes sense to try to keep DMS levels as low as possible in hop forward styles to prevent any sort of aroma competition.

I will likely make a few changes to my process after researching for this article. For example, when it comes to no-boil beers, I think I’m going to start boiling them. I’m already heating the wort for a no-boil beer anyways so why not just let it come to a boil? My memories of that previously un-boiled berliner I talked about really stick out to me as a good example of trying to purge that DMS out of the beer early on.

I’m also going to start experimenting with putting a piece of tinfoil over the small carboy opening on my Big Mouth Bubblers during the aggressive stage of fermentation and replace it with an airlock after around days 3-5. When I ferment in a keg, I might consider leaving the pressure release valve open to mimic an open fermentation to encourage more DMS removal by C02.

The next time I try capping the fermenter when adding dry hops in an attempt to retain hop aromatics, I’m going to think about waiting a few extra days than I typically would to make sure that first big drop in DMS has occurred. I might even try adding a tiny bit of yeast nutrient to boost the nitrogen content again to potentially prevent additional DMS from forming via the yeast.

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Effects of mash parameters on fermentability and efficiency in single infusion mashing

A PDF version of this article can be found here: Effects_of_mash_parameters_on_attenuation_and_efficiency.pdf

It is commonly known that there are many factors that effect the fermentability (limit of attenuation) of brewing wort. The series of experiments conducted here are aimed at understanding not only the qualitative impact but also quantify the changes of fermentability depending on the parameters that were considered for evaluation.

In Understanding Attenuation it is mentioned that final attenuation of a beer mainly depends on 2 factors: limit of attenuation (i.e. attenuation potential) and the yeast’s ability to come close to that limit of attenuation. The limit of attenuation is only effected by mashing and the Fast Ferment Test has been introduced to determine it. For simplicity sake, these experiments only focus on single infusion mashes and explore the effects of the following mash parameters:

  • saccharification rest temperature: This is the first factor that comes to mind for all grain brewers. For a single step saccrification rest, the mash temperature has a great effect on the fermentability of the resulting wort. The lower the temperature (within a given range of course) the longer the beta-amylase will be able to work and produce maltose. See The Theory of Mashing.
  • time: Along with temperature this is one of the more important parameters in mashing. It determines how much time the enzymes will have to work on the mash.
  • mash pH: the beta and alpha amylase enzymes have different optimal pH ranges and therefore the mash pH can effect the activity balance between these enzymes. See The Theory of Mashing.
  • grind: larger grits of endosperm make it harder for the mash water to fully hydrate them and make the starches accessible to the enzymes. As a result lots of starch is released later when the beta amylase activity has already diminished. The result of a coarser grind is a lower limit of attenuation. See The Theory of Mashing.
  • water to grist ratio: the enzymatic activity of the amylases is effected by the thickness of the mash. Thinner mashes enhance the maltose production and therefore increase the fermentability. See The Theory of Mashing.
  • grain bill composition (base malt): mashes with high diastatic power (Pilsner, Pale) will produce more fermentable worts since they contain a lager amount of beta-amylase which can produce more maltose compared to mashes with lower diastatic power (Munich or large amounts of unmalted grains) assuming the same saccrification rest temperature.



Materials and Methods

Figure 1 – The samples were mashed in a stainless steel thermos bottle.

Figure 2 – The mash was strained batch-sparge style though a wire strainer

Figure 3 – The wort was then boiled for 15 min over medium heat

Figure 4 – After the boil was complete, the hot wort was filtered through a paper towel set in a funnel

Figure 5 – Fermentation of the sample with bread yeast

All experiments were conducted at a relatively small scale with minimal overhead. The strike water was heated in the micro wave. The time spent in the micro wave was noted for each experiment and provided a guidance for future experiments. After a number of experiments it was possible to come close to a desired mash temp by estimating the necessary heating time. The water was then added to a small steel thermos bottle where it was left for about 5 min to settle and if necessary adjustments were made by heating it some more or removing the top to let it cool quicker. A Styrofoam stopper was fitted for the bottle which also held an alcohol filled thermometer. The tip of the thermometer reached into the water/mash and it was possible to read its temperature without opening the bottle. The settled temperature was recorded and the milled grain was sirred into the water. 5 min into the mash the mash temperature was recorded. It was also recorded 30 min into the mash. Then the mash was stirred and its temperature recorded 5 min later. The last time the temperature was recorded was at the end of the mash.

Once the 60 min mash was complete a sample of the wort was tested for starch conversion with iodine on chalk. This was not done for all mashes because sometime I simply forgot. The mash was then lautered through a stainer set over a pot. In all cases it took less than 2 min to bring the first runnings to a boil. In the meantime sparge water was heated in the microwave and the grain was well mixed with the water before it was lautered again through the strainer. This sparging technique resembled a batch sparge.

After the wort was boiled for 15 min it was strained though a paper towel set in a funnel. The funnel was placed into a clean 12 oz bottle. Initial experiments sanitized the bottles and the funnel in boiling water. But that became to cumbersome and due to the high pitching rate used the effect that infections could have on the attenuation measurement was deemed insignificant. As a result the bottles were only cleaned and somewhat sanitized in the dishwasher. The wort in the bottle was then topped of with reverse osmosis water when necessary to reach the same amount of final wort volume for all experiments. Initial experiments didn’t care about the precise amount of wort in the bottle as long as there would be enough for 2 hydrometer readings, but later it was decided to keep the volume the same to get a measure of the efficiency along with the attenuation.

After capping the bottle with aluminum foil, the wort was left to cool at room temperature. Once cooled the original extract was measured with a hydometer (range 0 – 40 Plato) and then pitched with 1/2 teaspoon of Fleischman instant bread yeast and later experiments used Shaw’s brand instant bread yeast. Dry bread yeast was chosen for its low cost and its consistency. In previous fast ferment tests, where it fermented along side other yeasts, it has been determined that it attenuates similar to other ale yeasts.

The samples were fermented at about 20 C (70 F) for 4-6 days. They were occasionally shaken to rouse the yeast. After the 4-6 days of fermentation the yeast started to settle and no visible signs of fermentation were left. The final extract (=final gravity) of the sample was measured with a more precise hydrometer (range 0.990 – 1.020). Both hydrometers were calibrated with various sugar solutions (20, 10, 5, 2.5 and 0 Plato) and the readings were also corrected for temperature.

Time experiments

For the time experiments, the following parameters were kept constant:

  • grain type: Weyermann Pilsner Malt
  • grain weight: 70g
  • mill gap spacing: 0.55 mm
  • reverse osmosis water and no pH adjustment of the mash. The resulting mash pH was measured as 5.4
  • strike water volume: 240 ml
  • mash starting temperature: 67 C and 72 C
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min

This series of experiments was actually done last, but it best illustrates how different temperatures effect mashing and as a result its data is presented first. To reduce the temperature drop during mashing, the thermos bottle was wrapped in sheets of foam generally used for packaging. But despite these efforts a temperature drop of ~ 3C/hr was still observed.

Temperature experiments

For the temperature experiments, the following parameters were kept constant:

  • grain type: Weyermann Bohemian Pilsner Malt
  • grain weight: 80g
  • mill gap spacing: 0.55 mm
  • reverse osmosis water and no pH adjustment of the mash. The resulting mash pH was measured as 5.4
  • strike water volume: 240 ml
  • mash time: 60 min
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min

pH experiments

For the pH series experiments, the following parameters were kept constant:

  • grain type: Weyermann Bohemian Pilsner Malt
  • grain weight: 70g
  • mill gap spacing: 0.55 mm
  • reverse osmosis water
  • strike water volume: 240 ml
  • starting mash temperature: 73 – 74.2 C
  • mash time: 60 min
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min
  • final wort volume: 15 min

The mash pH was ajusted with either white distilled vinegar (5% acetic acid) or baking soda (5% w/w NaHCO3 solution) which was added by volume with a small syringe.

The pH of the samples was measured at the end of the mash. Because the probe of the pH meter is getting old and its calibration function wasn’t working anymore, the correction of the measured value was done externally by measuring the sample, a 4.01 reference buffer and a 7.01 reference buffer. The following equation was used to determine the actual pH of the sample:

corrected pH = 4 + 3 * ((sample pH – 4.01 buffer pH) / (7.01 buffer pH – 4.01 buffer pH))

In addition to that, the samples were also tested with EMD’s colorpHast strips, which were read against the color scale in tungsten light. Reading them in fluorescent light actually changes their color. All samples were cooled to room temperature before measuring their pH. The pH meter that was used is a Milwaukee pH53.

Mill gap experiments

For the Mill gap experiments, the following parameters were kept constant:

  • grain type: Weyermann Bohemian Pilsner Malt
  • grain weight: 70g
  • mash average temperature: 68 C
  • reverse osmosis water and no pH adjustment of the mash. The resulting mash pH was measured as 5.4
  • strike water volume: 240 ml
  • mash time: 60 min
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min

The grain was milled with an adjustable 2 roller mill (Schmidling Maltmill). The gap of that mill was measured with a feeler gauge with an estimated precision of +/- 0.02 mm.

Mash thickness experiments

For the mash thickness experiments the following parameters were kept constant

  • grain type: Weyermann Bohemian Pilsner Malt
  • grain weight: 70g (for the 2.57l/kg and 5 l/kg series) and 120g (for the second 2.57 l/kg series)
  • mill gap spacing: 0.55 mm
  • reverse osmosis water and no pH adjustment of the mash. The resulting mash pH was measured as 5.4
  • the total amount of water used was 5.6 l/kg for all experiments. (70g grist used a total of 390ml and 120g grist used 670ml water)
  • lauter efficiency was estimated to be about 80%
  • mash time: 60 min
  • boil time: 15 min

The strike water was calculated to reach a mash thickness of 2.57 l/kg and 5 l/kg respectively. Because of the larger temperature drop that was encountered for the 2.57 l/kg mash with only 70g of malt, another series for that mash thickness was recorded with more malt and strike water to keep the actual mash volumes and temperature drops the same between the two series. After mashing additional water was added to adjust the total water use per grain to 5.6 l/kg. In order to keep the lauter efficiency the same for all these mashed this series of experiment was lautered using the no-sparge method in which all the malt and water were combined before the mash was strained though a strainer into the pot used for boiling.

Malt type experiments

For the malt type experiments the following parameters were kept constant

  • grain weight: 70g
  • mash average temperature: 70 C
  • mill gap spacing: 0.55 mm
  • reverse osmosis water with treatment as necessary to keep the pH values comparable
  • strike water volume: 240 ml
  • mash time: 60 min
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min

Since the color of the malt has an effect on the mash pH, one mash w/o adjusting the pH was done and based on the resulting mash pH the strike water was treated with vinegar or NaHCO3 solution such that the mash pH of the 2nd mash would be close to 5.3-5.5.

Calcium content experiments

For the Calcium content experiments the following parameters were kept constant

  • grain weight: 70g
  • grain type: Weyermann Pilsner
  • mash average temperature: 69 C
  • mill gap spacing: 0.55 mm
  • strike water volume: 240 ml
  • mash time: 60 min
  • sparge water volume: 250 ml
  • lauter efficiency was estimated to be about 90%
  • boil time: 15 min

To create mash water with varying levels of calcium ions but constant residual aklaklinity (which would change the pH of the mash) 1.05g calcium chloride and 1.00g chalk were added to 2l distilled water. This resulted in a water with ~343 mg/l (ppm) Ca and a residual alkalinity of 0. To create a strike water with different Ca concentrations, the treated water was blended with distilled water at varying rated. But In order to keep the Ca concentration in the final wort the same, the sparge water was blended by using the reverse ratio. E.g. if an experiment used 20% 343 mg/l Ca water and 80% distilled water, the sparge water would consist of 80% 343 mg/l Ca water and 20% distilled water. Since the chalk does not readily dissolve in water, the treated water was shaken before use to resuspend the chalk.

Results and Discussion


Figure 6 – The mash time dependency of the limit of attenuation and brewhouse efficiency shown for 2 different mash rest starting temperatures

Figure 7 – The iodine reactions of the mash liquid as they were recorded after the mash time was over. The iodine reaction was measured by dropping a drop of mash liquid onto a piece of chalk and adding a drop of iodine solution

When the relationship between mash time, fermentability (limit of attenuation) and extract efficiency was examined, 2 trends were observed. The lower of the two mash temperatures (67C / 152F) resulted in a slower initial increase in extraction efficiency and fermentability compared to the higher mash temperature (72C / 162F). This is explained by a lower activity of both the alpha and the beta amylase enzymes at the lower temperature. And in the long run the mash with the lower mash temperature was able to create a more fermentable wort. This is a result of the greater stability of the beta amylase enzymes at the lower temperature. While they are initially not as active as in the higher temperature mash, they are active for a longer time and can therefore produce more maltose which increases the fermentability.

At temperatures at which the denaturation of the beta amylase dominates (70C/160F and above) the beta amylase becomes more of a “sprinter”. It is able to create maltose at a higher rate due to the higher temperature which speeds up the reaction, but it denatures much quicker at the higher temperatures and as a result is not able to “cover as much ground” as it is able to at lower temperatures.

The higher temperature mash outperformed when it comes to extraction efficiency. This is a result of the stronger alpha amylase activity and possibly better gelatinization of the starches. Alpha amylase is the main enzyme for converting starch into water soluble glucose chains.

Unfortunately the temperature drop of the mash during the experiments was substantial ( ~3 C/hr, see Figure 8) which means that the beta amylase suffered less damage than it would have if the temperature for the 72 C mash would have remained at that temperature for a longer time. This can be seen in the continued increase of fermentability. While this could also be a result of alpha amylase activity it is assumed to be the result of lingering beta amylase activity. While alpha amylase is able to produce fermentable sugars as well it is not very effective at it. The effects of the increased denaturation of beta amylase can be seen in the steep rise of the fermentability that quickly falls behind the fermetability curve for the 67C mash temperature. This temperature dependent denaturation rate of the beta amylase is the main factor in the mash rest temperature dependence of the limit of attenuation.

Another observation (Figure 7) that was made is that the hotter mash was able to reduce the iodine reaction (indication for free starch in the mash liquid) quicker than the mash at 67 C. This is another result of the increased alpha amylase activity in the mash done at 72 C.

Figure 8 – Temperature profile for the various mashes done in this series of experiments. The average temperature drop was about 3 C per hour


The next series of experiments discussed here evaluated the effect of the mash temperature on the attenuation. Unfortunately the small mashing vessel that was used (stainless steel thermos bottle) and the stirring at 30 min caused a significant mash temperature loss. Because of that the average mash temperature was used as the x-axis in Figures 10 and 11. The approximate mash profiles for all the sample mashes that were done are shown in Figure 9. Dough-in happened at time 0 and the mash was quickly lautered after 60 min. The average mash temperature drop was 4C (8F). The wort pH was measured at 5.5 (at room temperature)

Figure 9 – The mash profile for the different mashes that were done for determining the attenuation dependency on the mash temperature

Figure 10 shows the limit of attenuation numbers that were measured for the various mash experiments in this series. Two things were surprising. First, all data points track along a curve very nicely and there is not much difference between points at similar temperatures. This is an indication for the high repeatability and low statistical error of this experiment. Second, the curve matches the few data points that are listed in one of the literature references [Narziss 2005] fairly closely.

Figure 10 – The attenuation, and estimated efficiency for the mash temperature experiment

Another remarkable observation is the almost perfectly linear shape of the attenuation slope after its peak. The linear function that has been fitted to match the data points has a slope of ~ 4 %/C. This means that increasing the temperature by one degree Celsius (1.8 F) will lower the limit of attenuation by 4%. This was found to be true over a fairly wide temperature range (12 C / 24 F). However, the slope leading up to the peak of attenuation is not as steep. This is assumed to be a result of stronger beta amylase activity which causes the production of maltose as soon as starch gelatenizes and alpha amylase is breaking down the amylose and amylopectin molecules into shorter dextrines. Literature sources that show data for the fermentability of single infusion mashes at various rest temperatures don’t show such a linear relationship past the peak of fermentability [Briggs, 2004]. It is assumed that the different shape of the temperature vs. attenuation curve shown in this experiment is effected by the relatively large temperature drop over the rest time.

In addition to the attenuation, an iodine test on chalk was performed at the end of the mash and the beginning of the boil. The results can be seen at the top of Figure 10. Note the mahogany color, witch is an indication of existing dextrines. This was expected to be seen for samples with a low limit of attenuation, but even sample number 10, which achieved 87%, shows a significant mahogany iodine reaction. More iodine tests for samples past the attenuation peak need to be added to confirm a trend. Surprisingly little of the iodine reaction carried over into the boil even though care was taken to heat to wort quickly to minimize the time spend in a temperature range that favors the alpha amylase activity (68 – 78 C/ 155 – 172 F). Note that this quick heating is not realistic in brewing practice where even without performing a mash-out, the collected wort spends some time in this range while it is heated to boiling.

Later experiments (number 12 and up) were done in a way that allows for a comparison of the brewhouse yield by recording the post boil volume. Because the lauter efficiency can be assumed to be the same for all experiments (all mashes were lautered batch sparge style with 1 sparge), the differences in brewhouse yield (also known as brewhouse efficiency) must be largely due to changes in the conversion efficiency (a measure of how well the mash converted the starches available in the grist). From the few data points that exist so far it is evident that lower temperature mash rests lead to a lower mash efficiency. Which is expected since not as many starches have gelatinized yet and the alpha amylase which is the major enzyme responsible for liquefying starches is less active. Note that all experiments were done as 60 min mashes and that the lower efficiency at the lower mash temps can be accounted for by mashing for a longer time.

Figure 11 – The expected limit for the final extract of a beer brewed from a 12 Plato (1.048 SG) wort in relation to the mash temperature

Figure 11 shows another twist on representing the attenuation data. For this chart, all the brewed worts were assumed to have an extract content of 12 Plato (equivalent to 1.048 SG). Instead of showing the limit of attenuation, the attenuation was used to calculate the lower limit of the final extract (=gravity) of the beer. This is the extract reading you would expect to get from a fast ferment test or a very well attenuating yeast which left the beer with very little or no fermentable extract.


pH meter vs. colorpHast strips

Table-1 pH adjustments and the measured pH values

Table-1 lists the pH corrections that were done to the mashes and the pH that was measured with a pH meter and the pH determined with colorpHast strips. The first column lists the experiment number and the second column the amount of acid or baking soda solution that was added. It is interesting to see that the pH meter measurements for experiments 19 and 23, which both received no pH treatment, are fairly close while the strips must have been interpreted differently between the 2 experiments. Another remarkable observation are experiments 24, 25 and 26, which received different amounts of acid, caused different pH meter readings, but all read 4.7 on the color scale for the pH strips. This effect was also observed when I tested the pH meter against the strips a few months back. The results of that test are published here. The next section will show that 2 of these 3 samples (25 and 26) show very different limit of attenuation values which leads to the conclusion that there was indeed a pH difference between the two.

Figure 12 – A plot of the colorpHast reading vs. the corrected value from the pH meter

Figure 12 shows a plot of the colorpHast reading vs. the corrected pH meter value. The error was at most 0.5 (sample 24), which is significant enough to matter in brewing, but it happened at a pH level which is generally not achieved in mashing.

mash results

The mashing experiments for the pH series were performed with a single infusion mash that started at or around 73.5 C (164 F). This temperature is well on the slope that was determined earlier in the temperature series of experiments. The results of the pH experiments are shown in Figure 13.

Figure 13 – iodine reaction, limit of attenuation and brew house yield as a function of the mash pH

Figure 14 – A comparison of the wort colors after a 15 min boil for experiments 23 (pH 5.5) and 22 (pH 6.5). The darker color of the higher pH wort is remarkable. It is a result of the stronger maillard reactions at the higher pH.

Figure 15 – For experiment 28 (mash pH 4.55) the wort at the end of the mash and the beginning of the boil was tested for starch and both tested positive

The first observation was that the optimum for the limit of attenuation (fermentability) seems to be between pH 5.4 and 5.6. This matches the pH range that was given for the beta amylase enzyme in Narziss [Narziss 2005]. In addition to that the shape of the curve matches the attenuation data that Narziss lists for a few pH values. But he gave no information about the mash temp, mash thickness (though ~ 4 l/kg is likely) or other parameters that can effect the limit of attenuation. Because of that it can be assumed that all pH values given in that book were measured at room temp.

Outside of the 5.4 – 5.6 range the limit of attenuation declines. The slope of decline is steeper towards lower mash pH and a little less steep towards higher mash pH. This might be the result of a different decline of beta amylase activity. Number 26 is an outlier, but can be explained by being mashed at a lower than average mash temp. Though the termperature series showed an attenuation decline of 4% for every degree Celsius, it is unknown if this relationship also exists for low mash pH conditions.

The brewhouse yield (also known as brewhouse efficiency) also shows a dependency on the mash pH. This is not new as many home brewers report an increase in their brewhouse yield once they correct the mash pH to be in the optimal range for mashing. The optimum for the brewhouse yield seems to be near a pH of 5.2-5.3, which is a little lower than the optimum for the fermentability. This might be the result of of better alpha amylase activity in that range, although Narziss reports the alpha amylase pH optimum as being between 5.6 and 5.8 [Narziss 2005]. At the extreme end of the pH range that was tested are 2 outliers for brewhouse efficiency. Experiment 28 was done close to a pH of 4.5 and its brewhouse efficiency was greater than the efficiency for the experiment done at 4.8 pH. The same is true for experiment 22. But when that experiment was repeated as 27, the resulting brewhouse efficiency followed the established trend. It is assumed that the measurements were incorrect rather than being unexpected peaks of efficiency.

The iodine reaction at the end of the mash followed the trend that was already seen for the limit of attenuation and the brewhouse yield. The least reaction remained in the optimum mash range of 5.2 – 5.6 while at the extremes to either side native starch was still present in the mash liquid after a 60 min mash (purple color of the iodine test). Unfortunately no iodine test results are available for either of the two experiments that didn’t receive any mash pH treatment. For experiment 28 (mash pH 4.55) the boiled wort was tested in addition to the mash and starch was still present. This shows that a pH well below 5.0 does not provide sufficient enzymatic activity to convert the mash. As a result of that the attenuation and brewhouse yield suffer and native starch will be present in the wort and subsequently in the beer.

Having a lower brewhouse yield and stronger iodine reaction also contradicts the pH and temperature ranges shown for the alpha amylase in John Palmer’s How To Brew [Palmer 2006]. There it is shown that the alpha amylase is active well towards 4.5 pH and below.

Mill gap spacing

Figure 16 – limit of attenuation and brewhouse yield as a function of the mill gap spacing.

Figure 16 shows the results of the mill gap spacing series of experiments. The limit of attenuation shows little dependency on the tightness of the grind. This seems to indicate that either only little new starch is released from the coarser grind during mashing or that the beta amlylase shows activity throughout the duration of the mash. Given that the mash temperature was 68 C, similar to one of the temperatures in the mash time experiment it is assumed that the relatively small change of attenuation is a combination of both.

The brewhouse yield shows more dependency on the tightness of the crush. The tighter the crush, the higher the brewhouse yield. But the difference between a 0.35 mm (13 mil) crush and a 0.95 mm (37 mil) crush was only about 10%. Reports of significantly increased brewhouse efficiencies by home brewers after adjusting the mills to crush more tightly led me to expect a larger difference. But some of the default malt mill settings for home brewers and home brew stores are also greater than 0.9mm (37 mil) which was not taken into account when the decision was made to only evaluate mill gap spacings between 0.35 and 0.95 mm. The brewhouse yield dependence on the mill gap spacing can be explained by the larger amount of flour and smaller grits that are produced with a tight crush. These make it easier for the mash water to access the starches which is necessary for the enzymes to convert them into soluble carbohydrates (i.e. dextrines and sugars).

The literature reports that finer grists result in higher levels of fermentability. This behavior was not confirmed in this experiment but given the higher conversion efficiency that is achieved with the finer grists and the relatively unchanged fermentability it can be said that the finer grists produce more fermentable extract compared to coarser grists. If this was also the case for mashes that show less conversion efficiency sensitivity towards the mill gap spacing (e.g. if the close to 100% conversion efficiency is achieved with any mill gap spacing within a given range) such mashes would likely show a higher fermentability for finer grists.

Figure 17 – iodine test on a piece of spent grain from experiment 33 (0.95 mm) (circled in red)

For experiment 33 (0.95 mm mill gap) a piece of spent grain was taken from the spent grain, crushed on chalk and tested with iodine (Figure 17). The result was a deep black-purple reaction that is an indication of the presence of native starch. This shows where the lost efficiency is it is still present as native starch in the grain. But this was also the case for the spent grain from mash experiments with tighter mill settings. For some reason the mash experiments don’t achieve the level of conversion efficiency which I commonly see in full size 60 min single infusion mashes. An indication of that is already present in the iodine tests which oftentimes showed a residual reaction after 60 min, something I don’t see in full sized mashes either. One reason for that could be temperature loss and lower level of agitation (stirring) that happens for the experimental micro mashes.

Mash thickness

Figure 18 – the effect of mash thickness on attenuation and efficiency

The results for mash thickness were somewhat surprising. Contrary to common believe no attenuation difference was seen between a thick mash (2.57 l/kg or 1.21 qt/lb) and a thin mash (5 l/kg or 2.37 qt/lb). Home brewing literature suggests that thin mashes lead to more fermentable worts, but technical brewing literature suggests that the mash concentration doesn’t have much effect in well modified malts [Narziss, 2005]. Briggs cites data that doesn’t show a change in fermentability when the mash thickness is changed [Briggs, 2004]. This was confirmed by these eperiments where all the data points were on the same curve that had already been established in the temperature experiment.

Note, that the experiments for the 2.57 l/kg mash were run twice because the initial experiment resulted in a small mash volume that lost 5 degree Celsius over the duration of the mash. To keep the temperature drop between the experiments the same the mash volume was increased and the result was a 2 degree Celsius temperature drop which matched the temperature drop for the 5 l/kg mash. But in the end that didn’t make a difference.

A significant difference was however found in the efficiency. The brewhouse efficiency of the tick mashes remained almost constant between 58 and 60% over the temperature range of the experiments, but the brewhouse efficiency for the thinner mash showed a strong dependency on the temperature and was always better than the efficiency of the tick mash. That leads to the conclusion that thinner mashes perform better and allow for better extraction of the grain. Briggs also reports that thinner mashes can convert more starch but that most of the conversion potential is reached at a water to grist ratio of 2.5 l/kg [Briggs, 2004]

Malt type

Figure 19 – The limit of attenuation of mashes with 3 different malts at a mash temperature of 69C

Figure 20 – The brewhouse efficiency that was achieved with 3 different malts at a mash temperature of 69C

Different malts, especially malts kilned at different temperatures provide different amounts of enzymes to the mash. This change in enzymatic strength leads to differences in the limit of attenuation and extraction efficiency.

Figure 19 shows the attenuation results for 2 different pH values for each malt. There is not much difference between the light Munich (Weyermann Munich I) and the Pilsner malt. But the dark Munich malt shows a significant drop in the limit of attenuation when mashed at about the same rest temperature. This is a result of lower beta amylase activity due to the significantly reduced beta (and to some extend also alpha) amylase amount. Note that the Dark Munich experiment with the lowest attenuation was also mashed at a rest temperature that was about 2C higher than the average for the other malts at this pH. If we assume that there is a 4%/C drop of attenuation (as shown in Temperature) the limit of attenuation at a comparable mash rest should have been a little higher (about 63%).

Note that the limit of attenuation of a mix of these base malts would not be the weighted average of the individual malt’s fermentabilities. This is because the pilsner malt has much more enzymatic strength than the dark Munich and will raise the fermentability by more than what its actual weight portion of the grist is.

The brewhouse efficiency (Figure 20) was not as strongly effected even though the higher kilned malts showed a slightly lower brewhouse efficiency. This is somewhat surprising as recent full size (5 gal batch size) mashes with the Best Malz Dark Munich showed a much slower conversion than mashes that contain all or larger amounts of low kilned malts.


Figure 21 – The limit of attenuation and efficiency for 4 mashes with different calcium ion concentrations in the mash water. The numbers above the data points show the pH that was measured for room temperature sample of the mash

As mentioned earlier, none of the mashes so far has been able to get to a conversion efficiency where 100% of the starch in the grist is converted to soluble extract (mainly dextrins and sugars). This rarely happens in the full size brewing batches (5 gal) even if they are single infusion mashes. One difference between the micro and the full size mashes is that water that is used. The micro mashes used reverse osmosis water with an approximate dissolved solid content of 30-50 mg/l (=ppm) while the full size mashed use reverse osmosis water and brewing salts. Based on this it was suspected that the mineral composition of the water has more impact than simply though the residual alkalinity and subsequently the mash pH.

One ion of particular interest is Calcium. Briggs notes that calcium stabilizes the alpha amylase [Briggs, 2004]. But since alpha amylase is still fairly stable at common saccharification rest temperatures (below 70C / 160F) the stabilizing effect of calcium shouldn’t matter much.

The experiments showed a slight downward trend for the fermentability if the amount of calcium in the mash is increased. But the difference between the highest and lowest attenuation is only about 1% which is well within the error range for these experiments. Based on that I would say that the calcium content of the mash has no impact on the fermentability.

A slightly stronger effect was seen for the efficiency. Here an almost 3% span was observed but since this is based on only a few samples that didn’t match in their mash pH either the result may easily be called conclusive although the trend, the higher the calcium content the better the efficiency, matches the expectations.


Attenuation and efficiency of the mash are effected by many mash parameters. Some have more impact others have less. When using a single infusion mash, temperature and time are the best parameters that a brewer can work with to target a specific fermentability of the wort. The time should be long enough to allow for complete conversion of the mash or at least a wort that doesn’t contain any starch (negative starch test). This might be achieved after 15-30 min, but a longer mash rest may be needed to achieve the desired fermentability. The mash pH should always be controlled and kept between 5.4 and 5.7 when measured at room temperature (5.05 – 5.35 when measured at mash temperature). This pH control can be done through the brew water design (residual alkalinity) and/or acid/salt addition to the mash.

Brewers that don’t mill their own grain will not be able to effect the tightness of the crush and will have to accept lower conversion efficiencies or ensure that the mash has enough time and “strength” to achieve an acceptable conversion of the starches. If the mill gap spacing can be controlled the conversion efficiency can be improved through a tighter crush. But at some point the crush might be to tight for a resonable run-off speed.

The thickness of the mash doesn’t seem to effect the fermentability of the wort that is produced but thinner mashes can significantly improve the conversion efficiency. As a result brewers who see low efficiency from their mashing may try to use a thinner mash (3-4 l/kg or 1.5 – 2 qt/lb) as they were shown to convert more starches.

When working with large amounts of highly kilned malts attenuation and efficiency problems can arise due to the lower diastatic power (enzymatic strength) of these malts. This can be counteracted by lower mash temperature and longer mashes or the addition of a diastatic stronger malt to the grist (e.g. 10-20% of Pale/Pilsner malt)

While the water composition may also have an impact on attenuation and efficiency besides the change in mash pH through the residual alkalinity, its impact is considered small and secondary.



Time series

Time series data.gif

Temperature series

Temperatur series data.gif

pH series

PH series data.gif

mill gap series

Mill gap and attenuation table.gif

mash thickness series

Mash thickness data.gif

malt type series

Malt series data.gif

Calcium series

Calcium series data.gif


  • [Narziss, 2005] Prof. Dr. agr. Ludwig Narziss, Prof. Dr.-Ing. habil. Werner Back, Technische Universitaet Muenchen (Fakultaet fuer Brauwesen, Weihenstephan), Abriss der Bierbrauerei. WILEY-VCH Verlags GmbH Weinheim Germany, 2005
  • [Palmer, 2006] John J. Palmer, How to Brew, Brewers Publications, Boulder CO, 2006
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Короткого хранения

  • 700г – зелёный перец
  • большой пучёк – свежая кинза (кориандр) и
  • одна большая головка – чеснок
  • 70г – соль
  • 2 дня сушить помешивая

Долгого хранения

  • 1кг – красный перец
  • 0.5ч.л. – Уцхо-сунели (fenugreek blue, Trigonella caerulea)
  • 1ч.л. – хмели-цунели
  • 1ч.л. – кориандр
  • 100г – соль
  • 100г – чеснок (одна большая головка)
  • 2 дня сушить помешивая
  • 500г перец
  • 150г чеснок
  • 75г соли
  • 2с.л. хмели-цунели
  • 2с.л. кориандр
  • 3 дня

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Improve mash efficiency in your stainless steel mash tun

Mash efficiency refers to the extent to which you are able to pull the sugars out of the malted grain and into the water. A high percentage of sugar recovery (75-90%) is called ‘high mash efficiency’. A low percentage (60-75%) is called ‘low mash efficiency’. Since the amount of sugar in the water correlates quite closely to the amount of alcohol you will have in the beer, it is important to understand mash efficiency in order to produce consistent results.

High quality beer brewing equipment

A low efficiency can be compensated for by increasing your grain bill (the amount of malted grain you start with). For example, if your mash efficiency is at 70% resulting in an alcohol content of 4% in your beer, you can increase your grain bill by 20% to bring the sugar and alcohol content higher. But this also adds cost to your brewing as the extra grain costs money and with more grain, you need a larger mash tun which also adds cost. The best way to increase mash efficiency is through proper technique.

First, it is important to ensure is that your ingredients are fresh. The yield will be lower with oxidized/stale grain.

Second, it is important to have a proper crush size and properly crush the grain. For most systems, a crush size of 0.04″ (1mm) is the best (if routinely seeing a stuck mash where wort will not flow through the grain bed, one solution can be to increase the crush size slightly). It is also very important that grain be ‘crushed’ and not ‘ground’. Grinding involves shearing of grain into fine particles (that gum up), whereas crushing sends cracks throughout the grain that open up to insides of the grain to water and enzymatic digestion. A 3 roller mill generally provides a better crush than a 2 roller mill, and the speed of the mill is also very important to maintain. The mill rollers should rotate at about 150rpm, whereas most electric drills operate at 600-1800rpm. Pulleys can be used, or a simpler solution is to purchase a variable speed drill and use it on a low setting. If the variable speed drill is a manual type (where depressing a button manually will be tiresome and inconsistent) it can be helpful to use a ‘120V fan speed controller’ to control the drill speed to 150rpm (if it is hard to calculate the speed, put a piece of visible tape on the drill chuck and count the number of times it passes each second—it should be close to 3/second). If the drill is not strong enough to turn the mill on low speed, the grain intake inside the hopper can be restricted to let less grain through at one time—it will take slightly longer but your crush will be more effective.

A third step is to ensure proper water chemistry. Water chemistry is a complex topic which we won’t get into here, but if you suspect water issues, try brewing with bottled (spring or RO) water that you know is fairly neutral, add the minerals you need, and compare results.

Fourth, ensure mash pH is around 5.2-5.3.

Fifth, ensure the grain is thoroughly mixed with the water. Clumps of grain and air can easily form when mixing the grain with the water. These clumps prevent water from accessing the crushed grain inside the clump, preventing the carbohydrates from being dissolved into the water and preventing enzymes from breaking the carbohydrates up into sugars that the yeast can digest. Mash in using the following steps:

  1. Ensure the pump is turned off as the grain should be given time to settle slowly.
  2. Add grain (mixed with rice hulls if using rye or a high percentage of high protein and/or no husk grain like wheat) slowly in a circular motion so it doesn’t ‘pile up’ on the surface, and allow time for the grain to sink naturally (for commercial customers our Grain Bag has a chute that is controllable and can make this easy).
  3. Dark malt should be crushed separately and added last as it tends to crush finer which impedes the flow of wort; keeping it near the surface ensures it does not form a dense ‘mat’ near the bottom.
  4. Ensure any grain/air clumps are broken up and a proper grain bed forms. The BREWHA Mash Mixer is an easy and effective way to mix the mash but do not overmix (as this can pulverize the grain increasing the chance of a stuck mash) and DON’T go near the bottom of the Colander to the disrupt the grain bed that has naturally formed by the larger grains settling faster through the water.

Sixth, closely regulate mash temperature. The enzymes that work to cut up carbohydrates into smaller sugars that yeast can digest (in the process called ‘saccharification’), producing CO2 and ethanol (alcohol) in the process, work best at specific temperatures. If the mash is not kept at the precise temperature the recipe calls for, optimal results and consistent efficiency will not be achieved. The first step to ensure the proper temperature is to ensure the strike temperature is sufficiently high. Since the grain addition will cool the water, the temperature of the water before adding grain should be above the mash temperature. Grain will generally cool water by 5-8C/10-15F so the strike temperature should be that much higher. After mashing in, check the temperature IN the grain bed with a thermometer to ensure the strike temperature was high enough. The mash temperature can be regulated with BREWHA vessels since the mash vessels (mash tun or fermenters) have built in ports for heating elements and temperature sensors to precisely control the temperature of the mash. If a large temperature rise is needed, the temperature in the cone can be set substantially higher than the mash temperature to reduce the time needed to raise the temperature in the grain bed; this is similar to a decoction type method which is explained more fully in the BIAC manual mashing section—see pg. 47 for details.

The seventh tip for increasing mash efficiency is by stirring or using a recirculating pump. The pump pulls wort (sugary water) out of the bottom of the mash vessel (past the temperature sensor and heating element under the mash screen) and puts it back into the top of the mash vessel above the grain bed. This circulating action provides movement of the enzymes and water past the crushed grain resulting in a more even temperature throughout the gain bed and the greatest interaction of the enzymes and grain carbohydrates, leading to greatest efficiency. When circulating with the pump, the return flow back into the mash vessel should be throttled with a valve to ensure the grain bed is not compacted as this will impede saccharification (enzymes converting the complex sugars/starches into simple sugars the yeast can digest) and could damage the heating element. mash recirculation ratesLet the grain sit for a minimum of 10 minutes before turning the pump on to allow the grain to absorb water and expand; start the pump with the return valve (on Mash Colander or pump exit) closed and open slowly until the proper recirculation rate is achieved (see the table to the right for recommended recirculation rates). Check the temperature of the returning wort to ensure it is not cooling the grain bed—particularly with a Small Colander, the return rate needs to be very slow, and cooling can occur in the hose; if this occurs, the temperature of the wort in the cone should be raised by up to 2C/4F above the mash temperature (a higher temperature is used with very low flow rates like are needed in the Small BIAC as more cooling occurs the longer the wort remains in the hose). If the wort level is rising at the top of the mash vessel, it indicates that too much volume is being moved by the pump and the flow should be throttled with the valve (install the valve ONLY on the downstream side of the pump either on the pump exit or on the Mash Colander port, or the pump will not work properly and could be damaged). If the wort stops moving down through the grain bed (or moves only very slowly) it likely means the grain bed is compacted and may need to be stirred up and reformed. If the pump plugs frequently when using the BIAC (due to grain falling to the bottom of the fermenter and entering the pump hose), the hose from the fermenter to the pump can be attached to the side racking port (instead of the bottom) to prevent grain from being drawn into the pump. With a very thick mash, channeling of the wort down through the mash may occur so use of the Mash Mixer at intervals to disrupt the top 4/5 of the mash bed can be helpful.

The eighth action is to slowly sparge the grain while lautering. The tendency at the end of mashing is to want to hurry the lautering and rush into boil. This is a mistake as far as increasing efficiency is concerned. Residual sugars inside the grain do not immediately flush out with fresh water but slowly diffuse out. If not given sufficient time (around 60 minutes to sparge and lauter is not too long) they will remain in the grain and recovery of sugar will be decreased. Hot sparge water (75C/167F) will generally give better results than cold sparge water as sugars are more soluble at higher temperatures.

To confirm that saccharification is complete, a starch/iodine test can be completed. If starch is still present, a drop of iodine will turn black. If starch is not present (ie. the enzymes have converted all the available starch into smaller sugars that the yeast can digest) the iodine will stay a yellow color. In most situations, wort will convert quickly (within 15-30 minutes) so the best way to check for starch (this tip was given to me by Ken Grossman of Sierra Nevada) is by removing a piece of grain and dropping the iodine directly on the grain; ideally the entire grain should stay yellow, but since this is rarely achieved at least all but the tip (where it is hardest for water/enzymes to get to) should stay yellow. If most of the grain turns black, let the mash run a while longer. (It goes without saying—don’t add the iodine back into the mash; throw it out or wash it down the drain.)

With an appropriate mash period (60-90 minutes is typical), proper crush size and water chemistry and by observing the above actions, consistently high mash efficiency can be achieved.

Proper crush size and tips for preventing a stuck mash

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Keptinis – Lithuanian baked beer

At Šnekutis Užupis

Farmhouse ale styles are known for being messy, sprawling, ill-defined categories to the point where it can be questioned whether they really are styles at all. The Lithuanian style keptinis, however, has a simple definition: it’s made from malts that are baked, often in bread shapes. Keptinis actually means “baked,” just as in the name of the excellent Lithuanian beer snack kepta duona (baked bread), which is bread sticks baked in oil and garlic. Unfortunately, the baking is just about the only point that all sources agree on.

There are two beers that claim to be keptinis on the market today: one is the only beer that Ramūnas Čižas makes, the other is brewed by Kupiškio. Even though I’d visited Čižas and tried both beers I couldn’t really answer the question of how this style of beer is made. After my visit to the library and some volunteer translation work by Remigijus Tranas that changed.

There seem to be four ethnographic papers that to some degree describe the brewing of keptinis (Astrauskas 2008). Unfortunately, I only have a translation of one of them, but that seems to be the most thorough, so I’ll chance a description based on this paper (Petrulis 1975). That paper in turn is based on questioning of just two people, so it’s not clear how definitive it is. In addition, Geir Ove got hold of the 1994 issue of Zymurgy, which has an article by Michael Matucheski on keptinis. And, I got some input via email from Simonas Gutautas of Dundulis. This blog post is the result of me trying to combine all of these into a coherent style description.

Today keptinis is associated with the area around the town of Kupiškis, but it’s clear that it used to be brewed in a much broader area in north Lithuania. I’ve also seen references to baked beer in other Nordic sources, so very likely baked beer has not been a purely Lithuanian thing, but this aspect is still vague.

Beginning of Petrulis’s paper

Looking at the beer itself, the first surprise is that Petrulis claims it was usually made from three types of grain:drooping brome, barley, and oats. Brome is generally considered a weed, but it’s sometimes used as fodder for animals. I asked Simonas Gutautas and he says for keptinis you would (if you were poor) use whatever grains were available, but barley was probably preferred. So while the people Petrulis interviewed used brome, this probably wasn’t a general rule. Matucheski appears to agree with Simonas.

Anyway, the grain is malted in the usual way. Then the malt is mixed with hot water to a thick mash, which as far as I can tell is not left to stand, but then put into the oven at a thickness of 17-19 cm on top of a layer of straw. Some people form bread shapes from the mash, while others just make a thick layer. It should then bake until it’s brown says Astrauskas, while Petrulis says it should be black as coal and crisp. Matucheskis says to bake at 177 degrees Celsius until the top forms a hard crust, usually 20-30 minutes, “but try not to let them brown”. Simonas says “a toasty crust” should form.

After baking, take the baked mash out and crush it with mortar and pestle, then mash it in the normal way together with hops and lime tree bark (Matucheski says lime tree flowers). The mash is left for 4-5 hours, and covered so that it will stay warm. No sour mash, in other words. Then, strain it through a cloth into the fermentation vessel and let it ferment. Neither Petrulis nor Astrauskas says anything about adding yeast, but Matucheski says yeast “was usually added”.

Note that there is no boiling, so this is a raw ale.

A mug full of keptinis

Petrulis says you’d use 1 pura of grain for 125 kvortas of water. That is 70 kilos of malts and 102 liters of water. The amount of hops would be depending on personal taste. Matucheski says for 19 liters of beer: 1 kg pale barley malts, 2 kg rye, and 2 kg oats, giving an original gravity of 1030 and a final gravity of 1010, which means 2.6% alcohol. That sounds very low. The two commercial beers are 5.2% and 5.7%.

According to Petrulis and Astrauskas keptinis is brown-black, with a sweet-sour taste, and “thick, sticky, heady”. (Doesn’t sound like 2.6% to me.) Simonas says it should be “reddish brown, rich in dextrines, full-bodied, sweet in taste and hoppy.” He agrees there could be some acidity from the toasted malts. Matucheski says it’s “gently sweet-sour” at first, then growing more “lactic” with time. Matucheski suggests using Belgian wit yeast, which might not be a bad suggestion, as Lithuanian brewers would use family yeast. The commercial variants are not sour, so I don’t think keptinis should be considered a sour style.

Using a home-brewer’scalculcator, if I plug in 70 kilos of chocolate malts and 102 liters of water, assuming 70% efficiency (probably a bit on the high side) and 75% attenuation, I’d get an OG of 1120 and an FG of 1030 for 11.8% ABV. These figures are very rough, but probably much closer to the actual beer than 2.6%. At a guess, I would assume typical ABV would be around 8-9%.

According to Simonas, making keptinis requires a large oven (for typical farmhouse batch sizes) and a lot of time, so it’s not easy to find any more. He implies there are still people other than Ramūnas Čižas who brew it. He also says Dundulis may brew a keptinis this year. I really hope they do.

And so we end as we began: although the basic definition of keptinis is firm enough (baked mash with straw, wort unboiled) everything else seems to vary wildly. A true farmhouse ale, in other words.


  • AlusJuozas Petrulis, in Kraštotyra. Vilnius, 1975. P. 237-248. Translated for me by Remigijus Tranas.
  • Per barzda varvejo, Antanas Astrauskas, Baltos Lankos, Vilnius, 2008. ISBN 978-9955-23-141-7. Parts translated for me by Elma Caicedo.
  • KeptinisAlus, Lithuanian Baked Beer, Michael Matucheski, Zymurgy – Special Issue: Traditional Beer Styles 14, 1994-1. Based on Markuza-Bieniecka (below).

Missing sources

If you could help me in any way to get hold of these, in whatever language and in whatever form, that would be deeply appreciated.

  • Chłodnik znad Niemna: kuchnialitewska by Biruta Markuza-Bieniecka, Watra, 1989. ISBN 8322502354. Thanks to a helpful reader on Facebook I now have this book.
  • Per barzda varvejo…, Vacys Milius, in Mokslas ir gyvenimas, 1969, nr 2, p 51.
  • Aludaryste Šiaures Rytu Lietuvoje, Dagys Viktoras, Etnografiniai tyrineji- mai Lietuvoje 1979 ir 1980 metais. Vilnius, 1981. – P.36-39

source: Larsblog

How to brew keptinis

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How to brew keptinis

The Jančys family brewhouse

Keptinis is a little-known Lithuanian style of beer where the mash is baked in an oven. The first farmhouse brewer I ever wrote about was keptinis brewer Ramunas Čižas. A few years ago I put together a description of how to brew keptinis based on ethnographic sources. Martin Warren followed my instructions, but ended up with just black, unfermentable water. So when Simonas invited me to come to Lithuania to see keptinis being brewed, he didn’t need to ask twice.

The Jančys family lives in nearby Utena, but often visits their farm in Vikonys, in north-eastern Lithuania, where they come from. And they still brew keptinis in the old way. The brewhouse is a small brick building on the farm, where Vytautas Jančys, who owns the farm, has built a brick oven specifically so he can brew keptinis. The art of brewing keptinis is something he learned from his father and grandfather, so he’s a real farmhouse brewer. He used to also make his own malts from barley, dried on top of the oven, until about a decade ago.

Starting the mash. Ignas on the left, Vytautas on the right

When we arrived, they had gotten the fire going, and were heating the brew liquor. Outside, in the yard, they’d set up the mashtun, and were getting ready to start mashing.

Vytautas poured a sack of pale malts from Viking Malts in Panevežys into the tun, then added buckets of boiling hot water while his son Ignas stirred the mash. They were using water, not juniper infusion, because this was Lithuania, not Norway. Vytautas kept adding water, and eventually started lifting the mash paddle, staring intently at the drops running off it. Then he would add some more water, then repeat. Finally, he was satisfied. Now they could pack up the mashtun and let it stand.

Judging the mash

But I’d seen no thermometer, so how could he know this was the right mash temperature? I went over to check with my own thermometer. It showed 65C. Simonas saw my surprise and explained to me what was going on. Since Vytautas was using boiling water the temperature of the water was always the same. So if he could hit the right ratio of water to malts, the temperature of the mix would also be roughly right. And this is what Vytautas was doing when he was staring at the paddle: he was judging the ratio of water to malts.

Now the mash needed to rest for an hour, so there was a pause.

The mash

Once the hour was up they started scooping the mash out of the mashtun and into metal boxes. These boxes are an innovation that Vytautas has introduced. In older descriptions and ethnographic videos the mash is formed into bread-like chunks where straw is used to help them stick together. The boxes are easier to use since they prevent the chunks from falling apart.

The mash boxes on top of the oven

Vytautas carried the four boxes in and put them on top of the oven. Then he used a shovel to remove the still-glowing embers from the oven. Putting on a plexiglass mask and big gloves he then put the four boxes into the oven, where they would bake for three hours. How hot the oven was I don’t know for certain, but clearly very hot. Simonas thinks the temperature is about 350-400C. This is at the beginning, of course. The fire has been removed, so the oven will slowly cool over the course of the three hours.

Putting the mash in the oven

Now there was another long wait, so Vytautas took us down into his cellar, where he keeps the beer. The June sun was hot outside, but down here in the cellar it was so cool it felt cold. The beer was stored in stainless steel kegs. Traditionally, people would use wooden casks, of course, but these are much harder to work with.

And there was another reason to prefer steel.

Pouring the beer

Vytautas put a plastic bucket under one keg and started to pour. Into the bucket ran what looked like porridge. The pressure in the keg was so high that what came out was pure foam, and we had to wait a good while before the foam turned into beer that we could actually drink. This is normal and traditional for Lithuanian farmhouse ale in general. Kegging the beer at the right moment to have enough CO2 in the cask, but not so early that the whole thing explodes is quite tricky, and serving the beer from wooden casks with primitive taps was also non-trivial.

The bucket was carried back up in the sunshine, poured into a ceramic mug, and served. The beer was deep dark red, nearly black, with a tiny beige head. It was quite sweet, with a massive flavour of toast, caramel, and earth. Very round and mild in the flavour, like a less roasted porter or a more toasty or caramelized brown ale. What was most impressive was the depth of the flavour, and at the same time how rounded and mellow it was. Deep notes of caramel and coffee lingered for a long time.

Serving the beer

It was a deeply impressive beer, and although this was a year ago, I still remember that massive earthy, toasty caramel flavour quite vividly.

While the mash was still baking they started preparing for the lautering. Ignas brought out wooden spiles of alder wood, which were soaked in water so that they wouldn’t float up and ruin the filter. Vytautas took us to the barn where a huge plastic bag of straw was hanging under the ceiling, so that the mice woudldn’t get into it.

Originally, they used the classic Lithuanian wooden lauter tun with a hole in the bottom and a long rod for opening and closing the hole. However, it’s a lot of work to keep these free of leaks and completely clean, so Vytautas has had a stainless steel replacement constructed. They put the wooden spiles on the bottom, then the wheat straw on top.

The baked mash

Now it was time for the mash to come out of the oven. The top of the mash was covered in a hard, dark brown crust. Some of the liquid had boiled over the side of the box, run down the side, and congealed in a hard mass at the bottom. I broke some bits off the top crust and tasted them: massively sweet and toffeeish, with notes almost like honey. They actually tasted like really sweet and good cookies.

And now I realized what was going on and why Vytautas’s beer had tasted so different. This is a dark beer made with pale malts, where the colour comes from the baking of the mash. In normal dark beers, the colour comes from drying the malts at high temperature. The heat makes the starch and protein in the malts go through maillard reactions, producing the colour and the roasty flavours. But in this beer it was the mash that had been baked. What went through the maillard reactions was mostly sugar, not starch. So of course the flavour wouldn’t be the same.

This is actually quite stunning.

Schwarzbier, porter, dunkel, stout, and all the other blackish beers are made from toasted starch, but keptinis is made from toasted sugar. It’s a different kind of dark beer. And, as the beer we’d tasted showed, one that could be really, really good. To make a proper keptinis you should really use Lithuanian malts and yeast, and not boil the wort, but the baked mash concept can be used to make many kinds of beers, not just a classic Lithuanian keptinis.

Breaking the crust

Once the lauter tun was prepared, Ignas took a large wooden spoon and started breaking up the crust on the boxes. Then the fairly dry mash was scooped out on top of the straw. Ignas then got hot water in plastic buckets, and poured it on top of the mash. They let it stand for about 20 minutes, then let the dark brown, blackish wort run off slowly into a porcelain bowl.

Wort coming out

Meanwhile, they were boiling hop tea in a small pot. Keptinis, like all other Lithuanian farmhouse ale, is raw ale, so in order to get alpha acid out of the hops they are boiled in water. This is a simple solution that doesn’t require a big kettle and saves a lot of energy. The little pot reeked with lovely hop aroma, and after half an hour or so the hop tea (in Lithuanian, “apyny arbata”, literally hop tea), was ready. They used just bittering hops for this beer, but they told me that if you want more hop aroma you can put some of the hops in cold water to draw out the aroma.

Once the wort had been run off it was cooled with cold water from a garden hose, and poured into the fermentor. The Jančys family no longer have their own yeast, and have been using commercial yeast for the last 30 to 40 years. Before that they did have their own.

And with that they were done. Within a few days the beer would be finished fermenting, and transferred to cask.

For me this was quite an experience, to see a completely new type of brewing process. Today, keptinis is an ultra-obscure style of beer, made only by a few farmhouse brewers in north-eastern Lithuania, and by three commercial breweries. One being Ramunas Čižas, the other two being Dundulis and Kupiškio.

Of course, keptinis is not the only oven-baked style. This must have been quite close to how the Seto people used to brew. And, as it turns out, the full story is a good bit bigger than just the north-eastern corner of Lithuania. The summer of 2017, it turned out, was the summer of oven-baked beer.

We’ll dive into that story over the next few blog posts.

The church in nearby Andrioniškis


The recipe is for 130 liters of beer, which is what they usually make. 50 kilos of pale malts. Mash in at 65C, then let the temperature drop to 58C over an hour. pH at the start of mash: 6.1.

Then put the mash into an oven, where we think the initial temperature should be 400-350C. Make sure there is a good amount of water in the mash. Let the temperature drop over three hours while the mash bakes.

Take 120g bitter hops (14% alpha acid) and 50g aroma hops (5-6% alpha) and boil them for 30 minutes in 2 liters of water. There was no very clear aroma of hops in the beer, so some noble hop will probably work best.

Then lauter in the usual way, cool the wort, then pitch. They have used both modern dry yeast (probably Safale S-04, 19-25C, 2-4 days) and #16 Simonaitis (24 hours). To be honest, the yeast was not very prominent in the beer I tasted, so something fairly neutral should work. This beer isn’t really about the yeast profile, anyway.

The tricky part here is to judge when the fermentation is sufficiently done, and then transfer to closed keg where it should work up natural carbonation. If you keg too early things can blow up, and if you keg too late you’ll get flat beer.

In older times it was custom some places in Lithuania for people to ask their neighbours over to help judge if the time had come for kegging. If they decided it had come typically everyone would be served beer (kind of like oppskåke) and a party might well develop.

source: Larsblog

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Obi110 reuse using raspbx – How?


Obi110 was on end of support with no firmware upgrades.  On November 1 2017 Google Voice changed certificates and Obi110 failed with ” Backing off” Connection error.

Initially thought as DNS Server issue and tried all and when support refused any firmware updates for Obi110 to fix the certificate issue, I noticed a SIP alternative using a third party provider for incoming calls in the obhi forums. It is an although a  puny $6 one time charge, not sure how long this will last, I decided to find an open source solution for running own SIP Pbx. Googling resulted in Asterisk PBX solution and I had a spare raspberry pi w ( bought @Mircocenter for $5) that I could use.

Here are the steps to prepare raspberry PI:

  1. Download the raspbx from http://download.raspberry-asterisk.org/raspbx-10-10-2017.zip.
  2. Use a software like etcher to image it to an SD CARD (Steps: https://www.raspberrypi.org/magpi/pi-sd-etcher/)
  3. Add WIFI connection settings configuration file wpa-supplicant file.
    1.  sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
    2. Go to the bottom of the file and add the following:
      				ssid="your ssid"
      				psk="wifi password"
  4. Now reboot and log in using root and raspberry as a password. Change password for security and then run raspbx-upgrade.
  5. Added a static route in the router to use a fixed local ip.
  6. connect to the system using ” ssh [email protected]” , where IPAddress is the static IP of the raspbx box.
  7. Change timezone ( configure-timezone command ) and also keyboard and localization settings using raspi-config command)

Here are the steps to the configuration of the raspbx pbx:

( more info here http://www.raspberry-asterisk.org/documentation/#basicconf)

  1. go to http://ipaddress  to config the asterisk using FreePBX Gui.
  2. First, it will ask you to enter a password for admin and an admin user will be created.
  3. Using Menu -> Applications–> Extensions  create a new PJSIP Extension. (Don’t forget to Submit and Apply config  to save )Screen Shot 2017-11-07 at 11.32.11 AM
  4. Using Connectivity-> Google Voice (Motif)  configure Gmail Voice. In Gmail security, you can create a new app password and then use this app password here. Also, make sure Add Trunk checkbox and add outbound routes is enabled.Screen Shot 2017-11-07 at 11.41.18 AM
  5. Once you submit and apply. you should see a connected status as below.Screen Shot 2017-11-07 at 11.38.54 AM
  6. Open the outbound route created and remove the defaulted route password. Also, move this over the default Star Communication outbound route.
  7. Add a new Inbound route using Connectivity–>Inbound routes ( in the DID Number add the GOOGLE Voice number without any formatting like 2222332323. Also, add  set destination by selecting an extension that we created before.)Screen Shot 2017-11-07 at 11.49.25 AM

Test using Iphone or Android phone( Optional)

Download Zoiper SIP Softphone and add the extension and call any phone to see if the PBX is using the google voice account.

Here are the steps to configure Obi110: 

  1. use instructions from https://wiki.freepbx.org/pages/viewpage.action?pageId=4161592.Screen Shot 2017-11-07 at 12.06.53 PM.pngScreen Shot 2017-11-07 at 12.07.41 PM
  2. in the obi config ip, change the Phone port  Primary Line in the physical interfaces to use SP1 Service.Screen Shot 2017-11-07 at 12.01.41 PM
  3. Reboot the Obi110 and check SP1 Status. It should showScreen Shot 2017-11-07 at 12.10.57 PM

Now you should all set to receive and place calls using your phones.

source & comments: narahari

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Brewing Water Basics

For many brewers, water chemistry is treated as the last frontier of homebrewing. Oftentimes, it is ignored or at least not something homebrewers want to think about. The old adage “if your water tastes good, it’s fine to brew with” may be repeated, and believed. The brewer may work on refining recipes and take great pains to provide fermentation temperature control, but ignore the water used in brewing.

This is a mistake because the largest component of beer is the water. Managing the pH of the mash and the flavor contributions of the water can take a good beer to a great beer. While it’s true that poor tasting water will make poor tasting beer, the inverse is not always true. Great tasting water out of the tap may not be well suited to brewing. Additions to the water by the water supply company such as chlorine, or the more stable form called chloramine, keep your water supply safe for drinking but chlorine can negatively impact the flavor of the beer. In some areas, the water out of the tap may be high in bicarbonate or iron which can also negatively impact your beer. If you wish to not delve into water chemistry at all, it is advisable to use reverse osmosis water from the water dispensers at grocery stores or distilled water as it would be a blank canvas to start with. Even so, better beer can be made with paying attention to a few water additions and mash pH that will be discussed in this article series.

Where to Start With Brewing Water

Getting a water report from your water company, if using municipal water, is a great place to start. They should have all of the information available, but you may not get all of the information you need from them at first. They are required to test the water for safety, and will report contaminants and pesticides, but will not always give you the components that brewers are looking for in a water report. You can ask brewers around you about the water, but often the easiest way to get a report on what you need is by ordering a household minerals test from a testing company. If you have a well, this is likely the only way to get a report. One of the dangers will be dabbling with brewing water is to add items per a recipe without knowing what you are starting with, so the report is crucial before beginning. A popular company is Ward Labs, but there are others out there. A basic test should run under $35 for what you need. You will require sodium, calcium, magnesium, sulfate, chloride, bicarbonate, and total alkalinity.

It’s also important to find out if your water company uses chlorine or chloramines for disinfection of the water. In order to use any water for brewing, this is a steadfast rule: the water must be chlorine free. Chlorine will off-gas and/or boil off, but chloramine is a more stable form of chlorine and will not easily boil off. It can be removed via Campden tablets (potassium metabisulfite) easily. One tablet crushed and dissolved into 20 gallons of water and stirred well will remove chloramine (and chlorine) in most cases. Removing the chlorine, or purchasing reverse osmosis or distilled water should be the first step in dealing with water.

Understanding Minerals

brewing water mineral additions

The results from your water test will give you the ion concentrations in parts per million (ppm) or mg/l. These minerals are important for brewing water, because they can affect the suitability for use in brewing and have a flavor impact.

If you have iron in your water (look for discoloration in plumbing such as rust spots), it is generally poorly suited for brewing as it is detectable in very small amounts in the finished beer as an unpleasant metallic or even blood-like flavor. Iron should be under 0.1 ppm in the water. If you have sulfide flavors and aromas in your raw water (rotten egg-like smell), it will not be suitable for brewing. If you have some sediment, a filter will often help. Just be sure to send the water after filtering for testing if that is what you plan to use.

The major mineral ions will we be working with are as follows:

Calcium: Calcium is the primary ion that determines the hardness of the water. It helps with lowering the pH during mashing, facilitates precipitations of proteins in the boil (hot break), enhances yeast flocculation, and assists in preventing beerstone. Many lagers are made with very low levels of calcium, so it is not required but can be helpful in the amounts 50-100 ppm.

Magnesium: Also responsible for providing hardness to the water, magnesium can provide a sour/bitter flavor to the beer in amounts of 30 ppm or more. It has a laxative effect in much larger amounts. Malt provides all of the magnesium required for yeast health, so it is not required as an addition unless adding sulfate in the presence of a high calcium level (using Epsom salts, or MgSO4).

Sulfate: Sulfate is the ion that is used to accentuate hop bitterness by enhancing the dryness of the finish. Additions are normally avoided in continental lagers or only used in small amounts, often 30 ppm or less. In most ales, the ideal amount is 30-70 ppm. For highly hopped beers, the desired sulfate level may be much higher: 150-300 ppm for IPAs or west coast APAs. That amount will make the finish seem more crisp and dry. If using 150 ppm or higher, the chloride level should be under 50 ppm to avoid a “minerally” finish to the beer.

Chloride: Chloride accentuates a fullness or “roundness” of flavor in the beer, enhancing the malt sweetness. It is generally used in the 40-100 ppm range in many beers, but in the New England IPA style, the chloride is often over 100 ppm, up to 150 ppm.

Sodium: Sodium rounds out the malt flavors, and can be used in modest amounts (under 150 ppm). A higher concentration can make the beer taste salty, and having a high sodium combined with a high sulfate level can create a harsh bitterness. It is generally recognized that keeping the sodium at 0-60 is a safe bet. Using brewing water sourced from a water softener is to be avoided.

Bicarbonate: Bicarbonate plays a huge role in water chemistry for brewing. It raises the pH of the mash, so should be kept under 50 ppm for pale/light colored beers. An amber colored beer could use a bicarbonate amount of up to 150 ppm (depending on the grain bill). A very dark beer with roasted grains (like a stout) could easily go up to 200 ppm or even a bit more, as more bicarbonate is needed to balance the acidity of the dark roasted malts. As such, there is no ideal range for mashing water except that what is needed to achieve an appropriate mash pH. In sparge water, low bicarbonate water is desired to avoid tannin extraction from the grain. This will be discussed at length in our next article on water and mash pH.

Brewing Salts

The common brewing salts are gypsum, calcium chloride, Epsom salts, chalk, sodium chloride, and baking soda. These are available at the homebrew supply store, or can sometimes be found at your grocery market.

Gypsum  (CaSO4 or calcium sulfate) is used in brewing to bring calcium and sulfate to the water. This can reduce the mash pH, in a small amount as can calcium chloride.

Calcium chloride (Pickle crisp or CaCl2) is used to add calcium as well as chloride, and Epsom salt (MgSO4 or magnesium sulfate) is used for the magnesium and sulfate contribution. Plain old non-iodized table salt (NaCl2 or sodium chloride) brings sodium and chloride to the table.

Chalk: (CaC03 or calcium carbonate) has been traditionally used to raise mash pH in cases where it may be needed, but it doesn’t dissolve well without extraneous measures and is to be avoided in general.

In those rare cases where the mash pH should be raised, baking soda (NaHCO3 or sodium bicarbonate) is most useful.

Lactic acid or phosphoric acid is the most common acids used to lower the mash pH if needed.

A helpful comparison to brewing salts may be seasoning salts in cooking. Just as making chicken soup with a great recipe and fresh ingredients can be improved with a bit of salt or some bay leaf, a great beer base can be improved with a bit of tweaking of brewing salts. Too much salt in the chicken broth can ruin the soup, however; and too much of a brewing salt can ruin the beer. Using more conservative additions with the “less is more” idea is a great way to approach adding brewing salts to your homebrewing repertoire. You don’t want a “minerally” or harsh beer in the end after all your hard work!

There are brewing spreadsheets and books available to help you decide where to target your ideal concentrations of those ions, and Brewer’s Friend has both a basic and advanced water calculator to help you reach your goals.   We have given you give a range, and it is recommended to stay at the lower end of the range until you know what you like. You can always add more next time, but you can’t take it out. One pitfall that many brewers fall into as they delve into water chemistry is finding a water profile from a historic city and set that up as a target. That can be problematic, as it may not be what the breweries themselves actually used, as they may have preboiled the water to drop the bicarbonate or used water from another source. If a profile seems to have very high numbers, and you’d still like to make an authentic London porter, dig a bit deeper into what the breweries in that area did with the water before brewing with it. Brewing water with less than your ideal ion targets may seem a bit bland (think of the chicken soup seasoning analogy) but won’t be undrinkable as it would be if you add far too much of a good thing.

A good way to see what the brewing salts may do to your beer is to try it out. Pour a pint of your beer, and add a dash of table salt to it to see what chloride brings out. Next time, add some gypsum, to see what that brings to the beer.

If you are just starting in water additions, you can get by with gypsum, calcium chloride, baking soda, and lactic or phosphoric acid. We will discuss using those items as we discuss mash pH and delve deeper into water chemistry in the next article.

Source: brewersFriend

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