At Westmalle, we ferment our beer at a temperature of 64 °F (18 °C). This is the temperature at which we pitch the yeast into the fermentation tanks. During the fermentation process, the temperature rises slightly to around 68 °F (20 °C), but it does not go any higher than that.
The yeast we use at Westmalle is quite sensitive to temperature, and we have found that fermenting at a lower temperature helps to maintain the desired flavors and aromas in our beer. By keeping the fermentation temperature relatively low, we are able to achieve a clean and balanced fermentation profile.
In contrast, at Westvleteren, they ferment their beer at a slightly higher temperature. The yeast is pitched at 68 °F (20 °C) and during fermentation in their open fermenters, the temperature can reach as high as 82–84 °F (28–29 °C).
The difference in fermentation temperatures between Westmalle and Westvleteren can have an impact on the flavors and characteristics of the final beer. The higher temperature at Westvleteren allows for a more robust fermentation, which can result in a beer with more fruity and estery flavors.
Both breweries have their own unique approaches to fermentation temperature, and it is interesting to see how these differences can influence the final product. It just goes to show that there is no one-size-fits-all approach to brewing, and each brewery has its own methods and techniques that contribute to the distinctiveness of their beers.
In my personal experience, I have found that fermenting at a slightly lower temperature, similar to what is done at Westmalle, can result in a beer with a cleaner and crisper flavor profile. However, I also appreciate the unique qualities that can be achieved through a higher fermentation temperature, as demonstrated by Westvleteren.
To summarize, at Westmalle, the yeast is pitched at 64 °F (18 °C) and rises to around 68 °F (20 °C) during fermentation. At Westvleteren, the yeast is pitched at 68 °F (20 °C) and can reach temperatures of 82–84 °F (28–29 °C) during fermentation in open fermenters. These different fermentation temperatures contribute to the distinct flavors and characteristics of the beers produced at each brewery.