High Gravity Brewing
High gravity brewing is an advanced brewing technique that cannot be easy. A high-gravity beer is normally defined as one with an original gravity OG of > 1.075.
The term high gravity brewing may be somewhat confusing to a few home brewers when doing an online search. The term also describes how many commercial breweries brew and ferment a high-gravity beer and then dilute it just before packaging.
Some of the problems may seem intuitive, while others may not. Here is a list of the problems and their solutions you will encounter:
1. First, you will get a lower efficiency when brewing HG beers.
Account for the lower efficiency in your brewing software when designing your recipe. If you normally get 75% efficiency, expect to get 50-60% in the neighborhood when high gravity brewing.
2. You will get a lower hop utilization.
Trust that your brewing software will adjust the hop utilization and compensate for the higher gravity in your recipe. I’m sure there are formulas for adjusting hop utilization in high-gravity brewing. One tip to get better hop utilization during the boil is to add DME or LME at the end to get the gravity up to your recipe’s specs. This will allow you to get better hop utilization at a lower gravity during the boil. I added 6 lbs of DME at the end of the boil in my high-gravity recipe.
3. Your yeast will struggle with the higher gravity and alcohol content.
Choose an alcohol-tolerant yeast strain and build a huge yeast starter. Be sure to aerate well, preferably with pure oxygen, and add some yeast nutrients such as Servomyces to increase your chances of getting full attenuation. Instead of adding DME or LME at the end of the boil, you may want to add simple sugars often during the fermentation, along with more oxygen and nutrients, to create less stress on the yeast.
The process is similar to chaptalization (or sugaring) in winemaking but is done not to add more alcohol but to allow the yeast to adjust slowly to increased osmotic pressures.
4. Big beers often taste “hot” with too much fuel alcohol.
Start the fermentation in the mid ’60s (64-66° F/18-19° C) and monitor the gravity often. Fermentation temperature control is one of the most important aspects of high-gravity brewing that is too often overlooked. Fermenting at cooler temperatures may take a lot longer, but with some patience, you will be rewarded with better alcohol integration, fewer fusel alcohols produced, and smoother, more balanced flavors.
5. High-gravity brewing often ends up with a stuck fermentation.
If you’ve done everything you can to ensure good yeast health, you may need to add more yeast to finish the job, or, as a last resort, add Brettanomyces and call it a wild beer. Champagne yeast is a good choice for stuck fermentations.
Try moving the fermenter to a warmer location. Rouse the yeast often and be patient.
6. High-gravity beers may show some green flavors when young.
You may need to age your high-gravity beer for a long time, up to a couple of years in some cases, before it mellows and conditions out some of those “green flavors.”
But be aware that your hops will evolve as your beer ages. If you are brewing an American Barleywine, judges often expect it to taste like an IPA but with a lot of malt character and some residual sweetness. Taste your beer often as it conditions to get a good sense of when it is at its peak and ready to drink.
7. It won’t be easy to re-brew the beer and get consistent results.
Consistency is difficult even for normal home brew recipes. Be sure to take good notes throughout your brew day and during fermentation and good tasting notes during conditioning and aging. Pay special attention to gravity readings and the fermentation rate, weigh your nutrients and sugar additions, and annotate all the variables involved at the time of the addition.
If you get an award-winning beer, do your best to re-brew by following your notes to the letter. The biggest variable will be fermentation.
At the same time, be aware that there is a huge difference in the quality of the competition judge’s comments. You may have to enter your high-gravity beer in quite a few competitions to get a good consensus on its merits and faults before tweaking your recipe.
8. It is difficult to create balance in a high-gravity beer recipe.
I suggest you go with an established recipe, one that has won awards if possible. Otherwise, you will have to experiment.
One problem is that high-gravity brewing can be expensive. You will be using a lot of grain and hops as well as malt extracts (if you choose to go that route).
These big beers are meant to be sipped. So, expect it to take a while to finish a 12% ABV American Barleywine keg. On the bright side, you could bottle and cellar age the beers for many years, enjoying vertical tastings for a very long time.