Grady Hull, Assistant Brewmaster for New Belgium Brewing Company in Fort Collins, Colorado. Grady graduated from Colorado State University in 1994 with a BS in Food Science and Technology. After an internship with Coors Brewing Company he worked as a brewer for CooperSmith’s and Fleetside brewpubs in Fort Collins and Greeley, Colorado. In 1996 he began working at New Belgium where he is currently the Assistant Brewmaster. While working at New Belgium he received his MS in Brewing and Distilling from Heriot-Watt University.
The most important factor in fermenting these types of beers is to get the right yeast strain. Most homebrew shops have a good selection of Belgian yeasts but before you buy I would check out White Labs or Wyeast Laboratory’s Web sites. They have great flavor profile descriptions, recommended temperatures, alcohol tolerances, etc. Proper aeration at the point of yeast addition is also key to getting a healthy, vigorous fermentation going.
We ferment our stronger, Belgian style beers in the mid 60s °F (~17-19 °C), based on the flavor profile of our yeast. The flavor profile of any yeast is dramatically affected by fermentation temperature. High gravity beers fermented with Belgian yeast strains are already prone to producing high levels of fruity esters. Other factors such as higher fermentation temperatures and lack of oxygen will accentuate that. We use temperature control to balance the esters out. Small batches could be cooled with a water bath or fermented in a cool area.
For the health of the yeast, we aerate the wort at the point of yeast addition. We also add a small amount of zinc and a nutrient for newly propagated cultures. The most important thing to remember when handling yeast is to keep everything as sanitary as possible. I think the best way to aerate wort on a homebrew scale is to fill the carboy with wort, put a rubber stopper in the top and shake the carboy hard prior to adding the yeast. The air in the headspace should aerate the wort. Since you are using atmospheric air you can’t overdo it. I wouldn’t recommend bubbling air through the wort unless you have a sterile way to do it. If the yeast you are using does not have built-in nutrient (like in a smack pack) it won’t hurt to add some nutrient. The most important thing we do to maintain yeast health is to continually bring up fresh propagations, which the homebrewer does when they buy yeast.
Phil Leinhart, Brewmaster at Brewery Ommegang, in Cooperstown, New York. Phil has been in the brewing industry for over twenty years, and has worked in and studied brewing in England, Germany and the US. He managed for Manhattan Brewing and worked for Commonwealth and Harpoon in Boston, The Lion Brewery in Wilkes-Barre, Pennsylvania and at Anheuser-Busch as a brewing supervisor, quality assurance supervisor and in implementing a Siemens Process Control System in the fermentation department. He came to Ommegang in January 2007 and took over as Brewmaster in early 2008.
I would say the number one issue a novice brewer might encounter when trying to ferment a strong, Belgian-style beer would be under attenuation, which could be caused by several factors: poor yeast health, inadequate wort aeration with subsequent low yeast growth, a yeast strain that can’t handle higher alcohol levels, too low of a fermentation temperature, etc.
We attemporate the fermentations at Ommegang at around 79 °F (26 °C) because this is the temperature our yeast strain ferments best at and we’re trying to get good ester production. For homebrewing, ferment the beer in a room that is not too cool and remains at a consistent temperature.
To keep our yeast healthy we check the viability of the yeast before pitching by staining with methylene blue. Wort aeration is very important for yeast health and growth and therefore flavor production. Especially with higher gravity beers the yeast needs to have enough oxygen to enable it to reproduce adequately. Yeast handling and storage between batches is also very important for health. Keep the yeast as cold as possible without freezing it and store it as short a time as possible. I would think yeast starters would be advantageous.
A general rule of thumb for pitching rate is 1 million cells per milliliter per degree Plato of original gravity. For example if you are brewing a beer with an OG of 19.0; pitch 19–20 million cells per milliliter.
When you’re brewing these kinds of beers on a small scale keep the fermenter in a room that has a consistent temperature – you do not want the fermenter to get cooled prematurely. Also, most of the higher gravity Belgian and Belgian-style ales are brewed using a significant amount of highly fermentable sugar such as dextrose or candi sugar. This is used primarily to boost the fermentability of the wort resulting in a beer that is relatively drier and less filling with good drinkability.
Vinnie Cilurzo, Brewmaster and owner of Russian River Brewing Company (RRBC) in Santa Rosa, California. Vinnie was hired as the Brewmaster at Russian River when it was founded by Korbel Champagne in 1997. He and his wife bought the business in 2002. Over the years Vinnie has earned many awards for his brewing, including Small Brewing Company of the Year at the Great American Beer Festival. Russian River’s Redemption Blonde Ale won the gold medal for Belgian-and-French-style ale at the 2008 GABF.
The biggest thing I often see when I taste strong Belgian-style brews is that the beers don’t finish fermenting to a low enough gravity. This could be from either not enough yeast or not enough O2 in the wort, though sometimes we see the same problem in a really, really big beer. I’m a proponent of starting with a lower original gravity and having the beer finish at a lower gravity to end up with a drier beer with the same alcohol content as it would have been if it was started at a higher gravity.
The way that we ferment Belgian-style beers at RRBC is very easily obtainable for homebrewers. In most cases we start the fermentation out at 62 °F (17 °C) for the first couple of days then let it free rise up to whatever temperature is ambient in the room. This process helps keep some of the fusel alcohols down as well as some of the big esters and phenolics. The number of days you hold the beer at 62 °F (17 °C) is up to the brewer and really comes down to experimentation. You can’t hold it too long at that temperature, though, or else you run the risk of the beer not finishing because a higher temperature for the bigger beers will help the yeast carry on.
Back when we didn’t have a lab we would use the yeast from another fermenter as quickly as possible and if we had to hang onto yeast we wouldn’t store it for more than five days. Looking at it from a homebrewer’s vantage point, I’d say to make a big beer consider starting out by making a smaller beer, which will act as a yeast growth phase. Then pull this larger quantity of yeast and use it to make the bigger beer. A yeast starter is also very important to get the yeast cell count up to a high level.
We aerate, but we don’t use yeast nutrients. We use oxygen as opposed to compressed air, and using air is super easy for a homebrewer. An aquarium pump with one of those nifty stainless steel carbonation stones on the end of a 1⁄4” piece of tubing works great — this is how I aerated my wort as a homebrewer.
The bottom line for a homebrewer is that most people don’t have a microscope, so assuming that he or she uses a yeast starter or pulls a good quantity of yeast from another fermenter, probably adding a couple of cups of yeast should do the trick. On the rare occasion that I do homebrew I often add about a cup of yeast for an average gravity, so doubling that should do the trick.