High Gravity Brewing

Posted on 05.01.08 9:26PM under Alcohol, All-Grain, Bottle Conditioning, Brewing, Extract, Troubleshooting, Yeast

I wrote a post a while back about calories in beer. It was really fun to write, and even more exciting when Bob Skilnik called me out on a few ambiguous and incorrect statements I made. But just having Bob Skilnik reading my site was cool!

The other day, I got a new comment on there, with a commentor named Kiwi asking the following question:

So my question is, your 10%ABV russian stout (sounds most excellent) got to that % by the recipe…which has more… sugars? and a better yeast? I am trying to up my alcohol %, but not ruin my homebrew.

Such a great question deserves front page answers, not some answer hidden in the comments of an old post. So, Kiwi, this one’s for you!

First of all, thanks for the compliment on the sounds of my Russian Stout.

The amount of alcohol in a beer is directly proportional to the amount of fermentable sugar that’s in the wort that you ferment into beer. Generally, fermentable sugar comes from malted barley, and sometimes also malted wheat, rye, spelt, or oats, corn, or rice, and probably some others I missed. Normally, the malted grains are soaked in hot water to cause enzymes to break down the starches into fermentable sugars. Some grains like corn and rice need a bit more processing to get their starches accessible.

The malt extract you buy at the homebrew shop is a concentrated form of fermentable sugar. Someone else has soaked the grains and extracted the sugars, then packaged it for our convenience. Also frequently used in brewing is powdered corn sugar. Again, this has been processed so that you get a highly fermentable sugar product that you can add to your wort to increase the gravity. Gravity just refers to the sugar content. Higher gravity means more sugar, generally more fermentable sugar, and thus a higher potential for alcohol.

So for part one, you’re right. More sugar will give you more alcohol. This can be done with more malt extract, more grains in your mash, or a bit of corn sugar or other fermentable sugars. Just go easy on the corn sugar and other non-malt sugar sources. For a five gallon batch, I normally use no more than a pound or maybe two at the most, for a really big beer. Most of the time, I don’t use corn sugar except for priming the beer for bottle conditioning.

The sugar must be consumed by yeast in order for the alcohol to be produced by the yeast. This brings us to the second part of your question. A better yeast. It’s really hard to say that one yeast is better than another. Each yeast strain just has its own characteristics, just like each hop variety has its own characteristics. More important is pitching the proper cell count of yeast. The great Jamil has a very useful yeast calculator on his site.

When you use the calculator, you may find that you need to make a big starter or use multiple yeast packs. For example, for a 1.099 beer he recommends two packs in a three liter starter, or one pack in a seven liter starter. Or you could do it with two packs of dry yeast.

The other factor, especially if you’re bottle conditioning, is the alcohol tolerance of the yeast strain. There are a few yeasts made for high gravity. I know there’s a Trappist High Gravity, and also a Super High Gravity yeast from one or both of the liquid yeast labs. Fermentis also has a few higher tolerance dry yeasts. One is made specifically for bottle conditioning.

I like to use Fermentis US-05 dry yeast for all my beers (except for those like Belgians that rely heavily on yeast character). I have had great success with it at high alcohol levels up to about 10%, and bottle conditioning well, too. Some people recommend pitching a fresh bit of yeast when you bottle high gravity beers, to ensure that there will be viable yeast available to condition your beer. This is where the Fermentis T-58 is designed to work well up to 11.5% ABV.

So to answer part two of your question: it’s not necessarily better yeast, but rather a yeast that is well suited for high gravity and high alcohol beer. And make sure you use enough of it.

One thing that is also important with a big beer is proper oxygenation. Wort, once cooled, should be dosed with oxygen to about 8-10 ppm for best yeast performance. In case you don’t have a DO meter, you can just bubble it gently with oxygen for a “little while”. If you’re like me, and you don’t even have an oxygenation system, then you just need to pour it back and forth a few times to get it good and foamy (make sure you’re pouring it in impeccably sanitized vessels). But simply shaking around the carboy won’t cut it for a big beer. You need plenty of oxygen in there for the yeast to be at their peak performance.

The final part of your question is more of a statement. You don’t want to mess up your beer. I think that the yeast issues are most important for big beer, or for any beer for that matter. You should also look around on some of the homebrewing forums like Northern Brewer, Brew Board, and Brewer’s Knowledge Base for more advice on high gravity brewing. There are also often articles in the homebrewing magazines BYO and Zymurgy about high gravity brewing.

But I have to tell you something. I ruined a few batches of big beer before I got my issues ironed out so that I could make a big beer that was fully attenuated and fully conditioned. I drank several gallons of flat sweet high alcohol beer, but I learned something more with each unsuccessful batch.

Another strategy you might try is shooting for a more modest ABV, like 7%. That’s pretty similar to making a 5% beer, and you can gradually step it up from there. But my overall recommendation is to give it a shot. Don’t be afraid to make a mistake. You might have to risk a bad batch to make your best batch ever.

Good luck!

Read Comments

  1. Posted by Bob Skilnik on 05.03.08 6:53 PM

    Just to add my 2 cents; all things being equal…use a high attenuating yeast for a higher alcohol content.

  2. Posted by Iloh Uchenna on 01.13.09 2:11 PM

    Please i would like to know what could be the cause of low(>1.0) apparent extract in a high gravity beer. The throw is as follows:Sorghum 60%,Barley malt 30%,Sucrose10%.

  3. Posted by Keith Brainard on 01.13.09 8:53 PM

    I’ve never used Sorghum before, but I suspect it may have lower enzyme content, which would reduce extract efficiency.

    I also have to ask why you’d use so much sorghum if you were using Barley anyway.

    And also, the sorghum is malted, I assume.

    One more thing: extract efficiency could decrease with increasing gravity beyond a certain point just because you’d be leaving so much sugar behind in the mash. If you use a lot of grain, you’ll fill your brew kettle before you’re done rinsing the grains, and that will show in reduced efficiency.

    I don’t know how to increase enzyme capability other than mash longer, and do a starch conversion test with iodine before you stop mashing. It is also possible that some other gluten-free grain has higher enzymatic power.

  4. Posted by Iloh Uchenna on 01.14.09 3:19 AM

    It is true sorghum has low enzyme content but we normally complement for that using artificial enzyme like brewers amilique TS.

    The reason for much throw of sorghum is to reduce cost as barley is imported.

    Although we are having low extraction efficiency presently which we attribute to the poor filtrability of our mash filter, i am of the opinion, it may not be the cause of the low apparent extract.

    Maybe my question was not well framed. The beer has start of fermentation gravity of 14.6 P and expected attenuation limit of 1.6-1.8P, yeast pitching rate is 4.6g/hl. The yeast strain remains the same.

    What could beresponsible for the breakdown of dextrins to an apparent extract of >1P?

  5. Posted by Richard Hahn on 04.29.09 1:09 PM

    Help! Just finished cooking a 1.16 OG wort, and I’m terribly worried it won’t finish properly. I keg, not bottle, and all advice I find is for bottling. According to your post, I can pitch more yeast (prior to “bottling”) and aeriate with a pump (not comfortable with that one for sanitation reasons) or by pouring between sanitized containers. Would this work: rack from my glass carboy into a corny keg loudly (opposite of siphoning quietly); therby, aeriating as I keg the mostly-finished brew. I would then pitch the T-58 yeast and let the keg build pressure, or should I attach a fermentation lock to the “in” side of the keg to release pressure as needed by the newly added yeast? I plan to store the beer in the keg for at least 9 months .. do I do this under pressure as with bottled beer, or simply in a sealed, unpressurized keg. Should it be stored in the keg at basement temperatures (65F) or refrigerated (39F)? Thanks for any advice … seems there’s not a lot of specifics for keg conditioning readily available. I also, typically, force carbonate in the keg instead of using priming sugars; therefore, it’s not like I have a giant, 5-gallon bottle to draw similarities towards.

  6. Posted by Keith Brainard on 05.01.09 3:41 PM

    You can take some steps now to help ensure your fermentation completes.

    Hopefully you used an online yeast calculator like Mr. Malty to determine the appropriate starter size to use. If not, you can still make a starter and add yeast. For 1.160, you’ll need a GIANT starter, or many packs of dry yeast.

    I made a 17.3% beer in which I used US-05 in as a starting yeast, then some EC-1118 “Champagne” yeast, and finished off with a bit of the White Labs 099 “Super High Gravity” strain. I also did incremental feeding, starting with a 1.060 wort, and making three separate additions to add more fermentable sugars each time (Sean Paxton’s DFH120 clone recipe does this same thing).

    Each time I added wort, I added O2 and more yeast. But you don’t want to add O2 unless there’s going to be more yeast activity after adding the O2. O2 is food for yeast, and if it’s not consumed, it will oxidize and stale the beer. (Of course if your beer is meant to be like a Barleywine, some oxidation might be OK)

    You may want to prepare a big starter of alcohol-tolerant yeast, pitch it at it’s peak of activity, and add a minute of O2 (or a bunch of pouring back and forth if you don’t have O2). You could start the starter now and pitch the yeast in a day or two when it’s gotten really active and built up some cell count.

    Definitely force carbonate this beer. My 17.3% monster was half the reason I got kegs in the first place. I would never want a beer like this to end up uncarbonated. It’s one thing if your house IPA doesn’t carbonate one batch, but this is your Grand Cru.

    As for storing the beer, I would force carb it as normal and leave it that way. Probably higher temperatures would accelerate aging, but you’d need higher CO2 pressure to get the carbonation level you want. So either temp should work OK. The great thing is that you can easily sample it whenever you want and change temperature conditions if you want to.

    Good luck with your giant monstrous beer. Should make a good New Year’s Eve celebration!