Control fermentation temperature: This will dictate taste of your finished beer. In most cases it’s the deciding factor that sets an off-flavor lager apart from a clean one. It is more than a detail in brewing. Yeast behave differently depending on whether it is fermented at warmer or cooler temperature. You have to handle this variable with care.
Ferment IPAs and American Pale Ales in the 18-22 degree celsius range. In this zone, your yeast will be able to eat up sugars effectivly and create those nice fruity esters that you want out of an IPA or APA. Push it a bit hotter and your beer will taste harsh. Drop it a bit lower and your yeast won’t work because it will be too cold for them. Keep the temp consistent! Don’t let it vary. Yeast can handles being cold or warm, but they cannot handle temperature changes.
Why Temperature Matters in Brewing
You need more temperature control for your gear when making lager beers. Lagers is fermented at cooler temperatures, eight to twelve degrees Celsius is about right for a German Pilsner or a Munich Helles. That cooler temp inhibits production of fruity compounds that ale yeasts create, keeping it nice and crisp and clean. Because the yeast is working slower with colder temps, it will take weeks rather then days to ferment. You’re sacrificing efficiency here for clarity. Once it’s done fermenting, you’ll want to continue cooling it to condition, dropping the temp even lower to get proteins out of suspension and bring flavors together in a nice balanced way. Without this step, flavor won’t meld and the beer stay sharp and unfined.
Then there’s Belgian ales. At the warmer end of range, styles such as Saisons or Tripels really come into their own above twenty-two degrees Celsius. The heat drive yeast towards complex spicy and phenolic notes that give the beer its defining characteristics. It seems counterintuitive to let your beer get hotter but that is where its character lies. Be careful not to push past danger zone though. Anything north of thirty degrees sees yeast become stressed out and start producing those nasty fusel alcohols. Think nail polish remover or burning rubber, it is unpleasant. It is also impossible to correct in the bottle. Because, as I said earlier, you cannot age out bad temperature decisions.
When you get down to it, paying attention to the actual wort temp is far more important than watching for how warm air in your bucket gets. The reason why is because fermentation create heat as well (it’s called a “heat-releasing” process). When fermentation starts it will create its own heat and during that time of active fermentation your beer may be multiple degrees above what the ambient air tells you. Measuring it with a digital probe in the wort will tell you the true temp. Controlling that heat can be as simple as some type of wrap or using a chest freezer with a controller. No need to go all pro with this setup just yet, but you should of dont guess… Get in there and see for yourself.
Part of brewing is also managing your expectations, in addition to the chemistry of it all. You can’t hurry the lag phase, those initial starts by the yeast; you can’t make a lager clear in three days. It just doesn’t work like that. The process takes time and patience pays off in every pour. At long last, cracking open that bottle or tapping that keg is reward of having honored the process itself. Because of the controlled and measured temperature, yeast finishes job according to its own terms, which results in a cleaner and finally more balanced end-product.