Brewing a coffee stout today from request of a neighbor. I try to use local resources as much as possible, so I’ll be using the a cold brew from Smelly Cat Coffee House in my NoDa Neighborhood and cocoa nibs and vanilla beans from Savory Spice in South End.
Full disclaimer: I'm an engineer and get geeked up about the science of things...
Created a yeast starter:
The coffee stout final yield will be 11 gallons at 1.062 SG. Using the pitching rate for an ale at 0.32 million cells / mL / ºP and according to Brewer’s Friend I will need approximately 475 billion (yes, with a B) yeast cells. Now there are hundreds of different types of yeasts to chose from… Today I chose an WLP004 Irish Ale Yeast to help me replicate the infamous Guiness Irish Stout. Each yeast pack has about 100 billion cells (if not more) in them. Either, I could buy 5 packs at about $7/per, or create a yeast culture… I chose the cheaper option. With 2 packs of yeast, I made a 4L starter at 1.036 with a stir plate to give me a total of 626 Billion cells (I often over estimate to give me a nice safety factor.)
My setup is a HERMS (Heat Exchanger Recirculating Mash System) — I’ll link to my equipment later in a tab. In this setup, I utilize a Hot Liquor Tank (HLT) – No there’s not liquor in there! A brew day with diagrams can be seen fully at The Electric Brewery Page. I chose this system because I wanted it to be repeatable and I found it hard with other methods.
My recipe calls to heat up my initial strike water to 167°F. I use Deer Park Spring water due to the fact that city water often has chlorine in it which can be removed with chemical agents, but ‘ain’t no one got time for that‘. I made a couple of brews with tap water and noticed that I was often having an off-flavor in my beers that only started when I switched.
But I digress, to start I heated 6.875 gallons of strike water (to receive a thickness of 1.25 qts/ pound of grains) to 167°F.
After the water has been transferred, dough’d-in the 22 lbs. of grains to reach a mashing temperature of 152°F. Rule of thumb is you want your strike water to be about 14ºF higher than what you want your mash temperature to be.
Ideally the mash pH needs to be a 5.2 in order to achieve the highest efficiency and taste. One of which is water chemistry. Here, I’m trying to target the alpha-amylase enzymes to leave me that thicker, almost chewy beer that is indicative of a stout. For more about mashing and targeting certain enzymes during mashing, byo.com has a very good write up – In the future I might try using a step mash method for the dry stout profile.
To make a coffee stout I used heavier darker malts to add the almost burnt taste. Side Note, I am using DME because my limiting factor is a 10 gallon Cooler as a mash tun with a max grain capacity of ~24 lbs depending on the water/grain ratio. I also wanted a thicker body so I added some unmodified malts:
1. 12.5 lbs of Pale Malt, Maris Otter (3.0 SRM)
2. 5 lbs. Extra Light DME
3. 4 lbs. Caramel / Crystal Malt 40L (40 SRM)
4. 2 lbs of Flaked Barley (1.7 SRM)
5. 2 lbs. of Carafa III (525 SRM)
6. 1.5 lbs. of Flaked Oats (1 SRM)
SIDE NOTE: Homebrewing is a type of rabbit hole. You can make good beer using minimal techniques, but to go into making great beer, there are multiple considerations.... One of which is water chemistry. Bru'n water has a very good and elaborate write up of it here and has excel spreadsheet to enter in values of your water profile. I tend to 5.2 pH stabilizer. While there is an on going debate to whether it helps or not, I've produced very good beers while using it. Those deep into the water chemistry will try to match water profiles from all over the world for their specific beer types... Such as Dublin for an Irish Stout or London for a Brown Ale.
After mashing for about 15 minutes, I turned on the sump pump to circulate the wort through my coil submerged in a HLT to help control the temperature. This also acts a vourlaufing, or draining and recirculating, the wort to help clarifying it. Essentially the grain bed acts as a sieve through which the water can travel. As the wort circulates, the grain bed settles and the wort is clarified.
After about another 30 minutes, we have conversion! For those who remember 6th grade science class, iodine in the presence of starch within an aqueous solution changes color to a deep purple/blue color. This happens when the tri-iodide and penta-iodide ions formed are linear and slip inside the helix of the amylose (a form of start). The iodine test, in turn, changes the wavelength of light that is absorbed – resulting in a intense color purple. Science! Keep in mind that darker beers, like my coffee stout, it may be hard to tell whether there is a color change.
After conversion, I raise the temperature of the mash tun to 167°F to denature the enzymes. Then I rearranged my pump setup so that I can sparge and drain the mash tun into the boil kettle. This process, in order to achieve the maximum brewhouse efficiency (each grain has a sugar potential for maximum sugar conversion. Depending on your process, most achieve anywhere from 65% to even 90%.) Beer Smith does an excellent job listing the potentials of all grains that a homebrewer might use. The gif below shows good confirmation that the coffee stout will be a good color.
The next step is to sparge once the mash temperature reaches the 167°F. I utilize the fly sparge technique where I slowly replace the wort with water as I drain the sweet wort (wort that has yet to have been boiled, or yeast added) This process, ideally, should take close to an hour and in theory, the water washes the sugars from the grains as the drains through false bottom. I drain the wort until the runnings have reached gravity of 1.010 – at which point there’s a chance of polyphenols, or tannis (adds unwated off flavors and contributes to chill haze)
At the end, I collected 10.5 gallons at 1.047 SG – Missed by 0.005 points. Due to boil-off, I need about 13.5 gallons for a full 60 minute boil (I have found that I lose about 1.5 gallons per hour.) I added 3 gallons to reach the yield to give me a diluted pre-boil wort of 1.036.
Gravity: Specific Gravity is measured against pure water at 60°F which will measure 1.000 using a hydrometer. For smaller batches a refractometer is preferred due to the fact you require a lot less wort - But can't be used after fermentation... and in turn more beer :). When submerged into wort, the gravity reading tells brewers how much sugars are present within the liquid. As the yeast works, there will be less and less sugars present (and more alcohol ;)) in the solution until there is very little left. The difference is how brewers can tell the alcohol content of the beer. Hence, the higher the original SG, the higher the alcohol content.
Add the pot on the turkey fryer and raise to a boil being careful of a boil over — Once the wort comes to boiling temperatures, protein from the aqueous solution coagulates and rises in the surface in a foam-type substance. The easiest way of preventing boil-over is to reduce heat and stir. It is also important to have a vigorous boil to drive off unwanted flavors and to fully isomerize your hop oils.
Coffee Stout Boil Additions:
1. 1.0 oz. of Northern Brewer Hops (8.50% α) @ 0 minutes
2. 5 lbs. of Extra light DME*
3. 2.0 oz. of Northern Brewer (8.50% α) @ 30 minutes
4. 1.0 oz. of Nugget (14.0% α) @ 30 minutes
5. 2.0 oz. of East Kent Goldings (5.6% α) @ 15 minutes
6. 2 tabs White Labs Servomyces Yeast Nutrients.
7. 2 tablets, crushed of Whirfloc Tablets† (fining agents)
*DME is Dried Malt Extract – DME used for extract brewers to bypass the mash step and go straight to the boil. Used with a lot of beginner brewers.
†Whirfloc Tablet is a finish agent, like Irish Moss, coagulates and attaches to the unwanted proteins within the wort to help clarify the beer.
Chilling and adding to Carboys:
After the 60 minute boil is complete, it is important to chill the beer to pitching temperatures as soon as possible. This is called a ‘cold break’ in which it helps coagulate the proteins so you can separate them before transferring to the carboys. I use a combination of a counterflow wort chiller with a ice bucket to quickly chill the wort as fast as I can pump it out.
A counterflow chiller acts as an heat exchanger where the 2 fluids, one hot and one cold, flow in 2 separate direction in turbulent conditions. Ideally, this will intake ice cold water and boiling wort and output them as the others starting temperature. Of course there will be some loss, but this is the more efficient way.
The wort is added to the carboys at about 70°F – Keep in mind it goes from 212ºF to 70°F in less than a minute… As soon as it is full I top it off with a SANITIZED bung and a air stopper (Sanitation is VERY important at this point due to room-temperature sweet liquid is a safe haven for bacteria and unwanted airborne yeast. I like using StarSan for all my sanitation needs )
My final yield was 12 gallons at 1.060, 0.003 points below the projected gravity.
Pitching the Yeast:
After the wort is in the carboys and capped, I took the yeast starter that I created 24 hours before cooled it so that I can decant it. This is a popular method to use due to the fact that with large starters, you’re adding a large percentage of liquid to the beer which, in turn, can alter the flavor of it. When you decant it, you cool the yeast so the yeast collects at the bottom. You then pour the excess liquid from the top and you’re left with pure yeast. From the picture the more viable yeast is the thin white layer on top, but the rest is usable.
I chose to use sevomyces as it receives better results than with typical yeast nutrient with excellent results. Nutrients are needed for the overall health of yeast, this is thoroughly noted in Chris White’s of White Labs book ‘Yeast’ (Which I highly recommend.) The nutrients present alone in the wort is enough for making beer, but others such as zinc is best for overall yeast health. Servomyces provides this for the yeast along with others to provide a healthy fermentation. I have always had vigorous fermentation within 6-10 hours or pitching using this supplement. 2-3 weeks later, a new coffee stout is born!
The coffee stout is fermenting well and in about 10 days I will check the gravity to see if it is close to the final gravity of the beer.
To Be continued…
I know I know…. I said I was making a coffee stout…. Where’s the coffee come into place??? To make the stout a coffee flavored ones I’ll be adding the cold-brewed coffee, cocoa nibs, and the vanilla beans in the secondary… Stay Tuned!
I hope you enjoyed reading. Stay tuned as I post the progress of this coffee stout to the final drinkable product. Please leave comments below.