Cold Steeping Dark Grains vs Traditional Mash

Almost all of us go through the same stages in our brewing evolution, starting with the love of great craft beer and ending with several hundred (perhaps thousand) dollars worth of equipment used to satisfy our insatiable thirst. For many of us, the learning and tinkering is part of the fun, without which we could not progress in our skill, craft, and passion. That eternal quest to make even BETTER beer introduces new techniques, crazy ingredients, and even fancy technology that plugs in and has lights and stuff! Today, I wanted to explore the notion of cold steeping grains and the impact, real or imagined, it has on our beer.

Premise

Dark grains are kilned or roasted to a degree where they have no diastatic or enzymatic power and nearly all of their sugar reserves have been broken down and consumed. Therefore they do not contribute to the sugar or enzyme levels extracted in a traditional mash. Dark grains mainly contribute color and flavor. Dark grains include: Black Patent, Chocolate, Carafa, Special B, Roasted Barley, etc… Traditional mashing of dark grains at high mash temperatures results in added color and flavor, but often with the addition of harsh bitterness and astringency. However, they also help lower mash pH. The theory is that by removing these dark grains from the mash and cold steeping them instead, a brewer can achieve the desired color and flavor without much of the bitterness and harsh astringency.

Setup

The experiment will consist of two samples with the exact same batch of ingredients in the exact same proportions by the same brewer on the same equipment. The control will be a traditional mash with all grains steeped in the hot mash. The experimental sample will be the same recipe with only the base grains in the mash, and the dark grains steeped overnight and added near the end of the boil. After mashing, both samples will be boiled for 20 minutes to sanitize and to initiate a hot break. No hops will be added so that only the flavors and aromas of the sweet wort can be analyzed. No water modifications including pH adjustment will be made so the dark grain impact on pH can also be measured. For the sake of simplicity given the small brew size, a BIAB format with a full wort mash will be used.

Recipe

The recipe is for a simple Oatmeal Stout designed to produce 0.85gal of sweet wort after a 20 minute boil.
1lb Pale Malt Briess
2oz Flaked Oats
2oz English Chocolate Malt (450SRM)
2oz English Crystal Malt (80L)
1oz Roasted Barley (300SRM)

Control
Mash all ingredients at 154F for 60min using 3.2qt/lb water. Remove grains. Boil 20 minutes.

Experimental Sample
Steep last three ingredients in 1qt (3.2qt/lb) cooled boiled water overnight. Mash the first two ingredients at 154F for 60min using 3.2qt/lb water. Remove grains. Boil 15 minutes. Strain and add extract from steeped grains to wort and boil an additional 5 minutes.

Results

Dark Grains after an overnight steep

Dark Grains after an overnight steep

Unmarked samples of both the control and cold steep sample were given in two glasses to each of the attending 18 members. Everyone agreed that there was a huge difference in the two samples. Although the taste and nose was nearly identical in both samples, they varied greatly in astringency and mouthfeel. 61% of the members preferred the mouthfeel of the traditional mash, which was creamier and fuller bodied. However, 56% of the members also acknowledged that the traditional mash was noticeably more astringent and acidic.

The pH of the samples also varied during the mash and in the finished wort.

Starting water pH 8.16
Mash pH Control 5.41
Mash pH Sample 5.67
Steeped Grain pH 4.93
Final pH Control 5.34
Final pH Sample 5.43

Conclusion

Cold Steeping dark grains will certainly yield a less astringent but slightly thinner wort. We felt that for lighter beers like a Schwartzbier, cold steeping would be beneficial, but for the heartier dark beers like Porter and Stout, it may yield a beer that is lacking in depth and character. If you choose to cold steep your dark grains, make sure to closely monitor your mash pH, which will likely need adjustment. As a follow up, adding a third sample where the dark grains are added at mash out and sparge should also be analyzed and compared.

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