This will be my first attempt at brewing a higher gravity (higher alcohol) brew that I can age for an extended period of time. I’ve shied away from brewing higher octane beers for one reason: lack of oxygenation.
Homebrewers are well aware that yeast need oxygen. Before fermentation begins, and ethanol along with carbon dioxide is produced, yeast undergoes aerobic respiration and actively reproduces through budding, using all available oxygen in solution. Once inside the cell, oxygen is used to synthesize sterols, such as cholesterol. These molecules provide flexibility and strength to the membrane and improve overall yeast health. A healthy yeast cell population allows for a faster starting fermentation (although not too fast – that can actually be detrimental) and higher attenuation. This is especially true for higher gravity beers where the yeast will need to be the healthiest to complete fermentation. More oxygen also means less off-flavor production such as acetaldehyde and diacetyl.
According to Chris White’s and Jamil Zainasheff’s book Yeast: The Practical Guide to Beer Fermentation (which I recommend every homebrewer who is serious about yeast to buy), yeast need 8-10 parts per million (ppm) of dissolved oxygen. With either extremely vigorous shaking (splashing) or using an aquarium pump one can only get 8 ppm of O2 into wort. This may be adequate for smaller beers but since O2 dissolves less into a solution of higher gravity, more O2 is needed.
To get more O2 into my wort, I used an oxygenation system to inject pure O2 into solution. For about two minutes of O2 injection, one can achieve close to 14 ppm (Zainasheff and White, et al., 2010).
=======================================
So for this brew I wanted something big, malty, and alcoholic that can withstand some aging. To this end, I decided to brew a Russian Imperial Stout. I will also age the beer on Hungarian medium toast oak cubes that have been soaking in Woodford Reserve bourbon. I added two pounds of flaked rye for a really creamy and viscous mouthfeel. Despite that some brewers may suggest mashing high to get a full-bodied beer, I mashed low (150°F) since this beer will have plenty of unfermentables to make increase the body.
The recipe:
- 1.00 lb Rice Hulls (0.0 SRM)
- 2.00 lb DME Golden Light (Briess)
- 12.00 lb Pale Ale Malt 2-Row (Briess) (3.5 SRM)
- 2.00 lb Rye, Flaked (Briess) (4.6 SRM)
- 1.00 lb Roasted Barley (Briess) (300.0 SRM)
- 0.50 lb Caramel Malt – 120L (Briess) (120.0 SRM)
- 0.50 lb Caramel/Crystal Malt – 40L (40.0 SRM)
- 0.50 lb Chocolate Malt (350.0 SRM)
- 0.50 lb Chocolate Malt, Pale (245.0 SRM)
- 0.25 lb Black (Patent) Malt (500.0 SRM)
Mash in at 150°F for one hour
Mashout at 168°F and vorlauf
90 minute boil:
- 1.00 oz Chinook (90 min)
- 2.00 oz First Gold (90 min)
- 1.00 oz Amarillo (20 min)
- 1.00 oz Amarillo (10 min)
- 1 whirfloc tablet
- ½ tsp of Wyeast nutrient
1 Pkgs Northwest Ale (Wyeast Labs #1332)
1 Pkgs Rogue PACMAN (Wyeast)
1 Pkgs US-05 (Fermentis)
OG: 1.096
FG: 1.031
ABV: 8.5%
IBU: 89
Notes:
10/29/10:
Prepped starter. 1.040 wort (1.5L) with Wyeast 1332 at 9am. Added to the starter a smack-pack of 1764 – Rogue PACMAN yeast at 6:00pm.
10/30/10: BREWDAY. Mashed in at average of 150F for one hour. Went down to 146F but then back to 154F, and then back to 150F. Wort smells like chocolate! Firsut runnings around 1.075 at 17.5 qts. Not enough wort collected so added a sparge (batch) of 17 qts. Second runnings at 1.057. Collected a total of 6.8 gallons of 1.061 wort and 68% efficeincy into boiler. Only will be able to get 1.080 of 5 gallon wort. I grossly miscalculated how much grain I needed to get 6 gallons of 1.080. I should have ordered 15 lbs or more of pale malt. I wanted to use the second runnings for a smaller beer but no way was that happening. Needed more malt and added DME to hit target gravity. Original gravity of 1.096 with a low efficiency. Pitched at 72F.
10/31/10: Got temps down to 67F then 63F at night.
11/1/10: Found temps 67F with high activity – this must be high krausen stage. Added some ice to bring back down to 63F. Came home and found that primary exploded. Temps never went above 67F. Cleaned, and brought back to 62F. Must find a better way of controlling temp swings. 63F to 67F has a noticable effect on CO2 evolution.
11/2/10: Back to 67F in the morning. Added only a little ice to the bath hopefully to bring it to 65F. Activity is beginning to slow.
11/3/10: Holding at 65F. Activity is strong and steady. Temps at 68F in the morning.
11/11/10: Checked gravity since activity seemed to be next to nothing. Thick yeast head on top of beer. Gravity at this point is 1.040 (56% AA) and may have stalled. Brought into a warmer room and roused yeast. Temps increased to 73F and some airlock activity seen, but could be just evolution of gas.
11/22/10: Gravity has gone down to 1.031 and is completely devoid of activity. Tasted sample from fermenter however, and it tastes great. Full bodied and malty, sweet, with notes of caramel, chocolate and raisins. Roast and alcohol is slightly evident and needs to be mellowed with age. However, fermentation profile is very clean with little diacetyl and no fusels. Oxygen worked well and did its job.
11/23/10: Racked to secondary container for long-term aging.
12/15/10: Added 3 ounces of hungarian oak cubes – medium toast. These cubes were soaking in Woodford reserve bourbon. Added this (1-2 ozs as well).
Looks nice Jason! How long do you plan on aging it?
Also – how did you add the oak cubes? Just free-floating, or did you use a hops bag? Cubes would be easier to leave in the secondary than chips. I’ve got a bourbon porter planned, so I wanted to see how you did yours.
Hi Andy!
Soaked about 3 ozs of cubes in 3 ozs of bourbon for abotu two weeks and simply tossed everything in. I would suggest to stay away from chips. Contact time is very short due to increased surface area and chips can impart a very tannic-like wood character that is very strong IMHO. Go for cubes and age for longer. Honestly, you probably don’t even need to soak the cubes in the spirit, yo could just add it to said beer to taste. I decided to go this route because maybe the imparted flavor could be more complex. Only time will tell.
As for how long, well that depends on the taste. Since I used O2, there is no fusel alcohols associated with stressed yeast so I could keg it right now. However, I’m going to sample it every few weeks or so, bottle (via keg) when I feel it tastes good (this could months or a year or weeks), and age it further in the bottle.
The bottom line Andy about aging: let your taste buds be your guide!
Hi, I’m a big fan of your blog and your beer looks great. I wouldn’t happen to be able to try some of your beer, would I? Do you bottle? I live in Staten Island.
Hi Will,
Of course you can! However, I live in the Bronx and my opportunities for commuting to staten island are close to zero unfortunately.
However, I am a member of the new york city homebrewers guild. We meet up the third Tuesday of every month and try each others brews, give advice, get feedback, etc… They are a great group and if you like to Homebrew then this is a great club.
As for that imperial stout, it won’t be ready for a couple of months but I always have other brews in the keg ready to drink now!
I brewed a Russian Imperial stout a long time ago before I knew much about brewing and didn’t use an Oxygenation system…
I did pitch 3 vials of yeast to a 1.106 OG beer and it finished at 1.030… Now that I know better, I wonder how much more attenuation I would get by adding oxygen or by making a starter (and if it will improve the beer at all) since that beer was pretty tasty?
Have you done any more experiments on this?
Jorge,
Very interesting and good point. It’s my understanding that proper pitch rate and healthy yeast give you the best attenuation. Adding oxygen might or might not improve final attenuation but will improve the overall rate of attenuation. Two beers might finish at the same time and degree of attenuation, but one with O2 might get there better. For example, at 2 days post pitch, a 1.060 OG beer without O2 might be at 1.030 while one with O2 might be at 1.027… A better rate of attenuation will probably lead to better flavors of less flaws in the beer.
Oh well, that my rant. What we need is an experiment! I may have to bring this experiment into the lab.
Oh and BTW, since I used O2 in my brew – no off-flavors detected, no fusel alcohols even for 8.5% ABV.
Oh, also forgot…
3 packs for a 1.106 means you *just* barely underpitched. The smack packs(activator) each have 100 billion and you needed 372 billion.
A starter and O2 very well may have brought your attenuation down further.
J
True… I’m just surprised that my beer came out right with lack of oxygen, and not pitching with a starter… makes me question it a little…
I’ve made starters ever since and worry about oxygen but haven’t brewed a high gravity beer since…
My understanding is that oxygen helps yeast grow initially, which doesn’t have much impact on attenuation (provided you are in the right ballpark), but it does on conditioning of the beer both by not producing much off-flavors initially and having a larger ‘army’ of yeasties to clean up… It also reduces lag time and gets beer fermenting faster…
The factors that I believe had a bigger impact on my brew was good temperature control around 70 F…
No off flavors or fusels on mine either and I was right around the high 8 low 9% ABV…
Interesting to think, “what could oxygen have done for my beer?”
Sounds like you have a great setup, especially with keeping fermentation temps under control. I’m sure your brew was great, and maybe you’re wondering if could have been better with the oxygen. The bottom line is its hard to tell. I’m sure O2 does help though, even to a minimal degree.
Pingback: Homebrew Review: Imperial Stout Aged on Bourbon Soaked Oak Cubes « Brew Science
Pingback: First Place Showing: Imperial Rye Biere de Garde | Brew Science – Homebrewing Blog