Author: Jason Cipriani

Adding coffee to beer seems to have become fairly common practice over the last few years, with breweries dosing styles ranging from Blonde Ale to Stout with the roasty bean. Given its characteristic similarities to certain dark grains, coffee is usually the feature ingredient in so-called White Stout. I think it’s safe to say the use of coffee in brewing is here to stay, particularly during the colder months when darker beers are in season.

There are a few approaches to using coffee when brewing beer, all of which have their proponents and opponents. While one can certainly introduce coffee at some point during the actual brewing process, such as adding grounds during the mash or boil, it seems most brewers prefer dosing the beer with a volume of brewed coffee post-fermentation.

One of these approaches involves adding coffee made using hot water to the beer once fermentation is complete, simply brew up the appropriate amount of your favorite java and toss it into the beer. Quick and easy, this method has received some criticism from those who believe the hot steep extracts certain compounds that impart harsh characteristics to beer. For these folks, the ideal method involves letting the grounds steep in cool water over a long period of time, which is said to extract a smoother, more robust coffee character.

I rather enjoy coffee beers but haven’t brewed many myself, hence my curiosity as to whether or not hot or cold steeping actually made a difference. What better way to find out than to put it to the test!

| PURPOSE |

To evaluate the differences between Coffee Stouts made with either hot or cold brewed coffee and otherwise treated identically.

| METHODS |

In order to highlight the differences as much as possible, I stuck to a simple American Stout recipe.

Manic

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 6 gal 60 min 40.7 IBUs 40.6 SRM 1.049 1.013 4.8 % Actuals 1.049 1.011 5.0 % Fermentables Name Amount % Pale Malt (2 Row) US 11 lbs 89.8 Roasted Barley 1.25 lbs 10.2 Hops Name Amount Time Use Form Alpha % Magnum 21 g 60 min Boil Pellet 14.5 Hersbrucker 14 g 30 min Boil Pellet 2.2 Hersbrucker 21 g 10 min Boil Pellet 2.2 Yeast Name Lab Attenuation Temperature Flagship (A07) Imperial Yeast 75% 60°F - 72°F Notes Water Profile: Ca 52 | Mg 9 | Na 37 | SO4 34 | Cl 44 Download Download this recipe's BeerXML file

I started my brew day by collecting 2 identical volumes of RO water and adjusting each to the same desired profile– the Grainfather being a 5 gallon brewing system, I brewed 2 batches side-by-side and staggered the start time by 30 minutes. While my strike water was heating, I weighed out and milled the grain.

After mashing in, I checked to ensure both mashes were at the same target temperature.

I took a pH readings 15 minutes into each mash that showed, unsurprisingly, they were both at what the Bru’n Water Spreadsheet predicted. Someone forgot to snap a pic of the second batch…

While the mashes were mashing, I used my heat stick to heat the sparge water.

With about 15 minutes left for the first batch, both mashes were maintaining the set temperature.

Each batch was subsequently sparged with equal amounts of hot water, after which I turned the Grainfather elements on full blast. While the wort was heating, I measured out the kettle hops for both batches.

When the boils were finished, I chilled and transferred each batch to identical fermentation vessels.

Hydrometer measurements revealed both worts had reached the same OG.

I placed the fermentors next to each other in my chamber and left them alone to finish chilling to my desired fermentation temperature. At this point, I stole some leftover wort and made a single vitality starter using Imperial Yeast A07 Flagship.

A few hours later, I pitched equal amounts of the starter into either batch then let them ferment at 66°F/19°C for a week, at which point neither was showing signs of activity. Hydrometer measurements confirmed both had attenuated to the same target FG.

The time had finally come to introduce the variable. I made the cold brew coffee by combining 6 oz/170 g of freshly ground beans in 30 fl oz/0.9 L of water and letting it steep in my refrigerator for 18 hours. The liquid was then strained to remove any coffee grounds and I ultimately ended up with 24 fl oz/0.71 L of cold brew coffee.

Just prior to kegging, I used identical amounts of water and beans to make 24 oz/0.71 L of hot coffee using an Aeropress.

The differently brewed coffees were added to separate sanitized kegs before packaging commenced.

The kegs were placed in my keezer where they were cold crashed and burst carbonated. After a week of conditioning, I began serving them to unsuspecting tasters.

| RESULTS |

A total of 20 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the hot brew coffee beer and 1 sample of the cold brew coffee beer in different colored opaque cups then asked to identify the unique sample. At this sample size, 11 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, though only 5 (p=0.85) made the correct selection, indicating participants in this xBmt could not reliably distinguish a Coffee Stout made with hot brew coffee from one made with cold brew coffee.

My Impressions: When I first started sampling, I felt the cold brew coffee beer had an ever-so-slightly sharper bitterness to it compared to the hot brew coffee version. The difference wasn’t nearly as drastic as I assumed it was going to be, which showed in my blind triangle test performance– out of 10 attempts, I was only correct 5 times. As for the beer itself, the taster I trust the most, my wife, said it was the best Coffee Stout I’ve made to date. Roasty and malty with the coffee character rounding things out to create supreme balance. I will absolutely be brewing this recipe again soon!

| DISCUSSION |

There are some interesting methodological similarities when it comes to brewing coffee and beer. Just as serious beer brewers focus on specific mash temperatures, quality-minded baristas consider water temperature for every cup they brew. Whereas one might choose to use a hot brew method to extract roasty and acidic characteristics, a cold brew method is used to produce a sweeter and purportedly more robust cup of joe.

With the growing popularity of coffee beers, brewers have been forced to consider the impact coffee brew method has on their beer, with many opting for the cold brew approach in hopes of creating a smoother product with more coffee flavor. Given the drastically different temperatures and steeping times, as well as the myriad reports of either technique creating a distinguishable product, I was a bit shocked that tasters in this xBmt were unable to reliably distinguish the hot brew coffee Stout from the one made with cold brew coffee.

I’ve consumed my fair share of both hot and cold brew coffee, methods I’m convinced produced different flavors, hence my admitted conviction those differences would carryover to the finished beers. This isn’t brewlosophy (tm tm tm), so I neither collected data on the coffee itself nor attempted triangle tests on them myself, though after this experience, I’m very interested to look more into it. And I definitely plan to continue exploring the way different methods of using coffee in brewing impact beer.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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