Author: Matt Del Fiacco

Roasted grains are known for producing the chocolate, coffee, and roast characters we love in Stout and Porter. Traditionally, these grains are milled and mashed along with the rest of the grain bill, which not only results in said favorable characteristics, but some believe it also leads to the production of undesirable burnt, acrid, and even astringent notes. In the pursuit of mitigating this trade-off, many brewers have turned to the relatively modern method of cold steeping.

In general, cold steeping involves soaking crushed roasted grains in cool, usually room temperature, water for approximately 24 hours then straining and adding the resultant liquid to boiling wort that was produced without roasted grains. The thinking behind this method stems from the idea that warmer temperatures extract more of these undesirable traits, thus steeping in cool water over a longer period of time allows for the extraction of the good stuff while leaving the bad behind, ultimately making for a smoother and more pleasant roast character. Another purported benefit of this method is that the mash pH is unaffected by the acidic roasted grains, which can make for easier pH management.

As a lover of dark beer, I spend a lot of time brewing styles like Stout and Porter that can include upwards of 12% roasted grains. My process has largely involved mashing all of the grains together, and while I’ve enjoyed the beers I’ve made, I began to wonder if maybe there was a better way. Having never tried cold steeping before, I decided to see how it would compare to my regular process and put it to the test!

| PURPOSE |

To evaluate the differences between a Robust Porter made with roasted grains included in the full mash and one made using the cold steeping method.

| METHODS |

For this xBmt, I went with a tried and true Robust Porter recipe of mine that’s a bit heavier on the roasted grains in order emphasize any effect of the variable.

Cold Feet Porter

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5 gal 60 min 40.9 IBUs 36.4 SRM 1.058 1.017 5.4 % Actuals 1.058 1.019 5.1 % Fermentables Name Amount % Swaen©Ale 10.625 lbs 86.73 Crystal, Medium (Simpsons) 10 oz 5.1 Black (Patent) Malt 8 oz 4.08 Pale Chocolate Malt 8 oz 4.08 Hops Name Amount Time Use Form Alpha % Magnum 19.8 g 60 min Boil Pellet 12 Cascade 29 g 15 min Boil Pellet 5.5 Yeast Name Lab Attenuation Temperature Super Special (Ü) Bootleg Biology 74% 60°F - 72°F Notes Water Profile: Ca 50 | Mg 5 | Na 8 | SO4 36 | Cl 80 Download Download this recipe's BeerXML file

I built up a single large starter of a secret strain sent to me by Bootleg Biology a couple days beforehand.

A day before brewing, I crushed the roasted grains for one batch and added them to room temperature water at a ratio of 1 lb per 2 qts of water (0.5 kg per 2 L water)

The following day, I measured out each batch’s full volume of water then began heating them to strike temperature, staggering the start of each by about 15 minutes.

While the strike water was heating, I weighed out and milled the remaining grains for the cold steep batch as well as the entire grain bill for the full mash batch.

Once strike temperature was reached on each batch, I mashed and gave a gently stir to fully incorporate the grains into the water before making sure I’d hit my target mash temperature.

Lids were placed on the kettles and I set the pumps to recirculate. It didn’t take long for the color difference in the mashes to become obvious through the tubing.

I took a pH reading about 15 minutes into the mash that confirmed my assumption– with both volumes of water treated equally, the mash including the roasted malts had a lower pH than the one where the roasted malts were left out.

When each 60 minute mash was complete, I removed the grains and set my controllers to boil mode before measuring out the kettle hop additions.

The worts were boiled for 60 minutes with hops added as stated in the recipe.

With about 15 minutes left in the boil, I pulled a couple samples just for a color comparison.

I added the cold steep wort to the boil 5 minutes later, pouring it through a stainless steel hop sleeve to filter out the grains. The color difference at this point was much less stark.

Once the boil was finished, I ran each batch through my CFC directly into fermentation kegs.

Hydrometer measurements confirmed both worts were at the same 1.058 OG.

The fermentors were placed in my fermentation chamber and left alone for a few hours to finish cooling. Once at my desired fermentation temperature of 64°F/18°C, I evenly split a starter between the batches. With signs of activity absent after 10 days, I took hydrometer measurements indicating both beers had reached a similar FG.

I proceeded to pressure transfer each beer to a fresh serving keg.

The filled kegs were cold crashed overnight in my keezer then fined with gelatin and burst carbonated. After a few more days of conditioning, the beers were clear, carbonated, and remarkably similar in appearance.

| RESULTS |

A total of 23 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the cold steep beer and 1 sample of the full mash beer then asked to identify the sample that was unique. While 12 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, 13 (p=0.02) were capable of doing so, indicating participants in this xBmt were able to reliably distinguish a Robust Porter made with cold steeped roasted grains from one where the roasted grains were included in the mash.

The 13 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the 2 beers that were different. A total of 5 reported preferring the cold steep beer, 4 liked the full mash beer more, and 4 reported having no preference despite noticing a difference.

My Impressions: I was pretty unsure of what to expect from these beers when triangle testing myself and found I was able to pick the odd sample out 4 out of my 5 attempts. I perceived the cold steep Porter to be fairly inline with my expectations, the overall roast character was restrained and less harsh, which I believe consequently led to it being a bit more caramel forward than the beer made with the roasted malts included in the mash. I also detected more hop flavor in the cold steep, which helped in my triangle test performance. Overall, while I really enjoyed both beers, my preference was for the cold steep example.

| DISCUSSION |

One of the more common complaints from brewers of dark beers is that they end up being more ashy and astringent than desired, which some have chalked up to the type of roasted grain used or even water chemistry. However, understanding that temperature and time affect grain extraction, some brewers cleverly began cold steeping their roasted grains to help mitigate the issue, a practice supported by the fact tasters in this xBmt were able to reliably distinguish a Robust Porter made using the cold steep method from one where the grains were included in the mash.

Despite accepting that preference is largely subjective, I found it interesting that both the cold steep and full mash beers won the favor an equal number of tasters who were correct on the triangle test. While the cold steep sample better fit my mental idea of a Porter, participants weren’t necessarily aware of the style and hence were left to choose a favorite based entirely on their sensory experience. There’s really no good way of knowing, but I am curious about these tasters’ general preferences for Stout and Porter.

A common recommendation when it comes to cold steeping is to increase the amount of roasted grains used by as much as 3x in order to provide a similar strength of flavor as a full mash without the undesirable characteristics. My experience with the beers in this xBmt certainly supports the notion that, cold steeped roasted grains provides less overall character than when the grains are included in the mash, all other things being equal.

I’ll absolutely utilize the cold steep method again, but only in specific contexts. I’ll skip it when making styles like Russian Imperial Stout and Dry Stout where I actually prefer some of the characteristics that come from roasted malts being included in the mash; however, I think it’s a great option for styles like Oatmeal Stout and Porter, which I prefer to have a smoother roasted character.

If you have thoughts about this xBmt, please feel free to share in the comments section below!

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