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  • Bob Monroe

Brrrrrr, That's a Cold Mash

If you recall trial three was my first attempt at creating a non-alcoholic English-style brown, and while it created a pretty good beer it didn’t quite capture the rich, complex malt notes I’m looking for in a brown. So, for trial four I tried to improve upon the recipe and then in trial five I tried something completely new with some surprising results.

Summary of Trial Four

In trial four I made some tweaks to the malt bill to reduce the amount of roast flavors and increase the bready, caramel, toffee, and malty notes. To accomplish this, I eliminated the roasted Chocolate malt and included some dark crystal malts. The rest of the brewing process remained unchanged.

The results for trial four were again pretty good and well received by customers and me. I did achieve less roast and sweeter maltiness in this batch, and the malt character came through even more as the beer warmed. It still tasted a bit thin and fell a little flat on the palate.

While this batch was improved it still didn’t achieve the complex, rich malt character I’m looking for in a brown and made me start to wonder whether I could really accomplish this with the techniques I’m using. This led me to switch things up on batch five and try a very different process.

Summary of Trial Five

If you have been reading my blog since the beginning, you might recall the discussion about the two mashing techniques employed to brew NA beer. The first is a very hot mash with a small amount of malt which is what I’ve attempted with my first four trials. While this technique has been successful in creating a fully fermented beer with an ABV below 0.5%, it lacks some of the malt complexity that I’m looking for and tastes slightly thin.

This brings me to the second technique which is mashing at cold temperatures with a “normal” sized malt bill. The main advantage being that you’re extracting all the flavors from a full malt bill so theoretically you should be able to get similar malt richness as a full-strength beer. With trial five I attempted to test this theory and see if the cold mash technique could get me closer to a real English brown.

With some help from Briess and I decided to use a scaled down recipe for Foxy Throwdown Brown but substituted a mix of Vienna and Carapils for my base malt to further enhance the body of the beer. I cold mashed the malt overnight, heated it to mash temp the next day, boiled, chilled, and fermented just as I would in a normal brew.

Two surprising things were discovered during this brew, my starting gravity was much higher, and my attenuation was very high. This resulted in the two versions being 1.6% (Windsor yeast) and 0.8% (LA-01 yeast) ABV, respectively. This was extremely unexpected and hard to explain, though if you want to hear a couple theories read the nerd out section below.

While neither version of batch five would classify as non-alcoholic they do exhibit a richer malt character which is more in line with an alcoholic English brown and validated the potential for a cold mash technique.

For trial six I plan to test a couple theories on why I way overshot my target ABV and test a hybrid method where I cold mash a portion of the malt bill and then mash the remaining malts at a high temperature. Hopefully this will allow me to capture the malt character I’m looking for with the cold mash and develop the body of the beer through the hot mash.

Check back soon!

Nerd Out Section

Ok, here is where I lose my wife, but if you’re interested in some more details about batch four and five read on!

Batch Four Specifics

Here’s the recipe for batch four:

1 lb. Carapils Malt

8 oz Munich Malt

8 oz Crystal 120

6 oz Brown Malt

6 oz Crystal 60

1 oz Willamette Hops @ 15 min

Mash in at 175F.

If you compare this recipe to batch three, I’ve increased the Carapils and also upped the crystal malts, including the addition of some darker crystal 120 malt. The goal with both is to increase the body of the beer through dextrins (Carapils) and melanoidin compounds (crystal). I’m also hoping to increase the malt complexity and richness by including the crystal 120 which imparts notes of toffee, caramel, and dark fruit.

Here are the specifics on the batch four along with some tasting notes:

With batch four I again saw another decrease in my mash efficiency leading to a low starting gravity of 1.008. I saw slightly lower attenuation but in line with previous batches for each of the yeasts. The changes to the malt bill got me a little closer to the flavor profile I’m seeking but again fell short in body and the rich malt flavors I’m looking for. Because I seemed to be getting diminishing returns on my recipe adjustments, I decided to switch it up completely on batch five and try cold mashing.

Batch Five Specifics

Here’s the recipe for batch five:

3 lb. Carapils Malt

3 lb. Vienna Malt

8 oz Victory Malt

8 oz Crystal 65

4 oz Chocolate Malt

3 oz Roasted Barley

.5 oz Fuggle Hops @ 15 min

.5 oz Willamette Hops @ 5 min

Cold mash at 38 F overnight, rinse grains, bring to 152 F and hold for 45 minutes, then bring to a boil and proceed as normal.

You’ll notice right away that this recipe used significantly more malt than previous batches due to the different mash technique. The grain bill is a scaled down version of our Foxy Throwdown Brown with Carapils and Vienna substituted for the base malt.

Here are the specifics on batch five along with some tasting notes:

Two numbers immediately jump out at you with version five, the starting gravity and the attenuation. My starting gravity was much higher, more than double my gravity from the previous batch. While my mash efficiency actually went down slightly from batch four, I used about twice as much malt which resulted in a much higher starting gravity. So I suppose this should have been more of a “duh” instead of a surprise.

The high starting gravity would not be a terrible thing if it weren’t for the true surprise which was skyrocketing attenuation numbers. An attenuation of 70%, meaning the yeast consumed 70% of the available sugar and dextrins, is in line with what you would expect in a normal brew. This in turn led to an ABV of 1.6% which means this batch did not qualify as non-alcoholic.

My hypothesis for the high attenuation relates to the fact that after I collected the runoff from the cold mash, I heated it to 152F and held it there for 45 minutes. This is a standard mash temp which allows for beta and alpha amylase to break down complex sugars and dextrins which were extracted during the cold mash. This resulted in the final wort being much more fermentable than intended. The 35% attenuation with LA-01 shows that there was a good amount of glucose in the resulting wort.

While I was trying to develop a theory for my high attenuation, I went back to the Briess website and discovered another interesting tidbit. According to their trials they found that the cold mash would extract very little dextrin from the malt. If this is true than trying to cold mash Carapils malt to increase my dextrin content was counterproductive.

Conclusions and Tweaks

While it felt a little like starting over with batch five, it did produce some surprising results and taught me quite a bit about the cold mashing technique. It also gave me some clear targets to address with trial number six.

The number one thing I need to address is the high attenuation. To combat this, I plan to go back to my very hot mash (175F) to hold the wort at after the cold mash. Holding at 175 will limit the effectiveness of the enzymes in creating simpler sugars. Bringing the wort from 38 up to 175 however will mean that the wort will pass through that optimal 150 to 154F range for a period of time which could be enough to drive up my attenuation.

This brings me to another big change, instead of cold mashing all of the malt, I will only cold mash the specialty malts. The specialty malts I am using have very little diastatic power, meaning there is little enzyme activity, so even though the resulting wort from the cold mash will pass through the optimal range there will be little conversion due to lack of enzymes.

Once this portion of the wort reaches 175F I will mash in the remaining portion of the malt. Because this portion includes the Carapils malt I will theoretically extract the desired dextrins since it will be mashed hot instead of cold.

Stay tuned for trial six to see if any of my theories are proven out!



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