Through the entire brewing process, there is one specific point where your wort actually becomes beer. That specific process is fermentation. Prior to this step your beer is still wort (pronounced wert) and one key to a successful fermentation is the temperature of the wort.
To understand why the beer fermentation temperature is key to the creation of beer, we have to take a step back and review the role of yeast. Yeast is the active ingredient that causes fermentation in beer. Without yeast there is no beer. Beer is a living organism used in brewing to convert the sugars from malted barley into ethanol alcohol. Basically yeast consumes sugar and expels alcohol. This process is what is referred to as fermentation.
Because yeast is a living thing, it requires an ideal environment to thrive in. If that environment is too cold, the yeast will go dormant. Should the wort be too hot, the yeast will die.
Ideal Beer Fermentation Temperature
So what is the ideal beer fermentation temperature? Depending on the style of beer you are making, the ideal temperature is between 60 – 70 degrees Fahrenheit.
Of the thousands or more possible beers you could make, there are really only two main categories of beer. Ales and Lagers. There are people that will believe that they brew only lagers although for the most part they actually don’t. Often they are calling their beer a lager based on the flavor, color and aroma rather than the type of fermentation they are using.
A Lager is fermented with a “bottom fermenting” yeast where the beer is often chilled to 60 degrees Fahrenheit before fermenting. This typically means extra equipment is needed to keep the fermenting beer at a lower temperature through the duration of their fermentation.
What most newer brewers make are Ales which are made with a “top fermenting” yeast. They are typically fermented around 70 degrees Fahrenheit for the duration of the fermentation process.
Keeping your wort within these idea temperatures is the easiest way to ensure a great tasting beer. Although the result of high temperatures could result in the death of the yeast, a much more common problem is the production of off flavours. When the temperature reach around 10 degrees Fahrenheit above the ideal temperature range, fusel alcohols can be produced.
Fusel alcohols are a heavier alcohol that has strong solvent like flavours which normally won’t complement your beer. So always make sure your chill your beer to the ideal temperature prior to fermentation.
Problems often arise in summer when the ambient temperature is higher and often simply fermenting beer in a basement or cold room is enough. In hotter regions though, a temperature controlled room or fridge may be required to maintain temperatures. Maintaining that ideal temperature through the duration of your fermentation is a sure way to have great tasting beer.