Optimization of Extract and Fermentability of Grouse Malt

Over the past decade, we’ve pushed the limits of flavor and color and now have over 20 malted and roasted millet and buckwheat products for your brewing pleasure. We have also gained an understanding of how to best use Grouse malt when brewing. For example – Don’t pretend non-traditional malts are a direct replacement for barley maltdo utilize exogenous enzymes! While there are still a significant number of variables to explore, we want to communicate some of the insights we’ve gleaned thus far.    

With the help of Hartwick College Center for Craft Food & Beverage, we have conducted a multitude of lab scale mashing and forced fermentation experiments. While our end goal for this project was to formally define the typical extract potential and gain insight on fermentability across our malt brandsthe path shed light on several variables in the brewing process. 

The first step in our research explored the optimal mash regime for millet malt with a high temperature alpha amylase enzyme and a glucoamylase enzyme. Not surprising, we found the temperature achieved during the mashing process has the most impact for achieving a higher extract percentage. 

Product Highest Temperature Achieved Termamyl AMG Extract % 
MI1001 165°F Yes Yes 72.0 
MI1001 170°F Yes Yes 73.0 
MI1001 175°F Yes Yes 75.9 

 Mash: 45 min @ 131°F , increase to 165°F (or 170° or 175°) hold for 45 min 

As you can see, achieving a temperature of 175°F for a 45 minute hold yielded 3.9% more extract than 165°F, and an even more dramatic increase occurred within the 5 degree difference of 170-175°F. 

Next, we looked at what impact the length of the mash hold had on these factors. We tested a falling step mash holding for 60 minutes at 175°F then decreasing to 160°F for a length of 30, 60, or 90 minutes. This resulted in an overall difference in extract by .4%, and fermentability by .1%. This shows that spending an extra 30 or 60 minutes on the mashing process does not yield more extract or fermentability, on a lab scale.  

Product Temperature and hold time Termamyl AMG Extract % Fermentability % 
MI1001 160°F – 30 min Yes Yes 72.4 84.2 
MI1001 160°F – 60 min Yes Yes 72.2 84.0 
MI1001 160°F – 90 min Yes Yes 72.0 84.3 

Mash: 60 min @ 175°F ,decrease to 160°F and hold for 30 or 60 or 90 minutes 

Exogeneous enzymes are crucial to the optimal gluten-free brewing process, and there are plenty out there to choose from. We chose Termamyl (a high temp alpha amylase enzyme) and the AMG300L (a glucoamylase enzyme with the highest active temperature on the market) as our enzymes of choice. Ondea Pro is a popular enzyme circulating the gluten-free brewing community, so we decided to test it in addition to our standard enzymes to see what impact it hasOur studies found that there is a slight increase in extract percentage when Ondea Pro is utilized, but not a significant one. The results indicate the increase in temperature plays a more significant impact on extract, with a 3.9% increase without Ondea Pro, and only a 3% increase with Ondea Pro. 

 The data below is based on a rising step mash holding at 131°F for 45 minutes, then increasing to 165 or 175°F for 45 minutes. 

Product Highest Temperature Achieved Ondea Pro Termamyl AMG Extract % 
MI1001 165°F Yes Yes Yes 73.5 
MI1001 165°F No Yes Yes 72.0 
MI1001 175°F Yes Yes Yes 76.5 
MI1001 175°F No Yes Yes 75.9 


We are also aware of the increasing usage of Ceremix in place  of Termamyl and  Ondea in place of AMGWhile AMG does increase fermentable extract, there is concern that it also negatively affects head retention. Ceremix is an enzyme that is promoted as allowing brewers to avoid the high gelatinization temperatures we’ve found advantageous for achieving optimal extract.  In time, we look forward to sharing our experience with these enzymes.  

The last two experiments focused on the differences between utilizing a rising step mash versus a falling step mash. The results showed that both processes are beneficial and the utilization of one process over another depends on your goals for the mash and the brewing equipment available. Utilizing a falling step mash can be easier as this can be achieved by adding certain amount of cold water to drop the mash temperature. Not all systems have the ability to increase the mash temperature in an efficient manner. 

The data below shows a falling step mash – starting at 175°F for 60 minutes and decreasing to 160°F for 30 minutes – as well as a rising step mash – starting at 131°F for 45 minutes then increasing to 175°F for 45 minutes. While the overall mash times are the same the temperature hold lengths are different, and thus may play a factor in the data. The rising step mash leads to a 3.5% increase in extract compared to the falling step mash, whereas the falling step mash leads to a 9.4% increase in fermentability. 

Product Rising/Falling Termamyl AMG Extract % Fermentability % 
MI1001 Rising Yes Yes 75.9 74.8 
MI1001 Falling Yes Yes 72.4 84.2 


The rising step mash does have other potential benefits such as targeting a protein rest for increased head retention and potentially assisting in lautering. However, using a rising step mash does decrease the extract and fermentability of the wort, compared to the falling step mash.  

Currently, Grouse utilizes a falling step mash. Our mash protocol is to hit a mash in temperature of 175°F, hold for 30 minutes, then decrease to 165°F and hold for 30 minutes. The heat stable alpha amylase enzyme Termamyl 400 mL/ ton is added at mash in, and AMG 300600 mL/ton added after the temperature decrease. Utilizing this mashing process, we have mashed our products individually and have established the following numbers 

Products Extract % As Is PPG 
Pale Millet Malt 75.6 345
Pale Buckwheat Malt 68.4 31
Average Specialty Malt 75.0 34
Average Roasted Millet Malt 60.4 25
Average Corn Malt 59.7 27
*PPG numbers are based on a falling step mash with the use of Termamyl Classic and AMG 300L in a controlled lab setting 

*It should be noted that this data is in the context of Grouse’s products only and does not take other gluten free malt house products into account. This data came from a highly controlled laboratory and the data might not be replicable in a typical brew setting. 

We hope you find this information helpful and look forward to examining and communicating the results of experimentation in the near future!