My name is Tyler Newman and I’m a beer lover and brewer. While in Seattle, I was privileged to work for some of the best breweries in the United States, but I have since moved to Charlottesville where I am currently loving my “late 20’s retirement.” Here in Charlottesville, at Fifth Season, I have continued to pursue my love of beer and brewing. I feel blessed to be a part of a great work crew and community, which leads me to one of my favorite topics – coffee porter!
To start, I recommend consulting either the Beer Judge Certification Program website (BJCP.ORG) or looking up the beer style using Beerstyles.com to find the style guidelines for porter. Below I have guidelines for a basic porter to give you a good starting point.
In short, a basic porter is lower in alcohol than a stout and traditionally uses English hops and yeast, since porters originated in England. However, my coffee porter recipe is based on an American Porter so that it has a more neutral flavor profile. I like more neutral flavors, because I want the coffee to shine through the beer character. To honor the traditional English porter, I did go ahead and use Maris Otter (UK Malt).
I’ve tasted a lot of different coffee beers where there was either too much coffee or the flavor was harsh or over extracted. When the coffee is over extracted the flavors become burnt, bitter, and astringent. My first coffee beer was over extracted, because I left coffee in the fermenter for 37 hours! I’ve also had lots of beers that were like drinking a little beer with lots of coffee, but weren’t over extracted just blended incorrectly.
HOW DO WE DO COFFEE BEER!? I sat down with a knowledgeable barista—my brother—to figure it out! He helps manage Case Coffee, which is a coffee company in Oregon. He told me that you need 6 ounces of water for 10 grams of coffee or 0.6 ratio of water (or beer) to ground coffee. After consulting other sources via the internet, I found ample evidence supporting this ratio as an ideal blend for coffee beer.
Now that I had found the ideal ratio for brewing coffee beer (0.6 ratio of beer to ground coffee), I then experimented with different ways to add ground coffee beans to a porter beer. The first way I will address is “dry hopping” the beer with slightly ground coffee beans.
First, I had to determine how many ounces of beer I had so that I could add the correct amount of coffee beans. In my last batch, I had about 4.4 gallons (gal) of beer, which is the same as 563 ounces (oz) of beer, which can be seen in the conversion below.
4.4 gal*128oz (amount of oz per gal) = 563 oz
Next, I had to figure out how much slightly ground coffee beans had to be added, which I did by converting the grams of coffee in my ideal ratio to ounces (10 oz of beer to 6 grams of ground coffee). The formula to convert the mass (or weight) in grams (g) to mass in ounces (oz) is to divide the mass in grams by 28.34952 (this number can be found in a conversion chart or conversion calculator on the internet).
Here’s the math:
563oz/983 grams=.6 ratio of water (or beer) to coffee
983/28.34=34.68 oz of coarse ground coffee to dry hop
There are a couple problems using this method. For starters, using 34 oz of coffee is EXPENSIVE! Good quality coffee can cost up to $40, which is roughly the cost of a batch of beer. Additionally, the coffee must be ground to the proper size AND you would have to worry about leaving it in the beer too long, thus over extracting the flavor, giving your brew an overly burnt, bitter, and/or astringent taste. While “dry hopping” is a valid way to add coffee to a porter, I find it has way too many variables to consistently create delicious coffee beer.
The second way to add coffee to a beer is with a cold brew coffee. Some of the brewers from Dogfish Head would spike a Pabst Blue Ribbon, (better known as PBR) to see how much of an ingredient they would need to add in a scaled-up recipe. I decided to give their technique a try and ignore the science! I took about 6 oz/fl oz (ounces to fluid ounces) of beer and started adding about a teaspoon (tsp; 3 grams) of cold brew coffee (which is just chilled, brewed coffee of your choice) to each beer to see where the coffee would start to come through.
When I finally scaled everything up, I ended up adding about 1 quart (32 oz) of cold brew coffee to the finished 4.4 gals of beer. Alas, science won the day after all! By using this tasting technique, I still stumbled on the exact ratio that you’re supposed to use when using water to coffee or in this case beer to cold brew (563oz/907grams=.6 Ratio).
To find how much cold brew to add to a batch of beer you need to convert beer volume in gallons to ounces, find the .6 ratio using grams, and then convert the grams back to ounces/fluid ounces to find how much cold brew to add into coffee.
I recommend adding cold brew because it has fewer variables, is cost effective, and it’s easy. It’s also helpful listening to a barista and trusting science.