Without yeast there is no beer, it makes alcohol and produces the carbon dioxide that carbonates the beer after brewing, you owe it to yourself and your beer to know how it works and how to look after it.
The yeast used for making beer is brewers yeast and there are many strains available. Yeast is not an ingredient to skimp on, bakers yeast whilst it would technically ferment some of the sugars, won’t make a good beer.
Fermentation is a process that takes time and, most of all, your patience. If you set up the ideal conditions for your yeast, a sweet delicious wort with plenty of nutrients, the yeast thrive. They reproduce and eat their way through the sugars and during the process produce alcohol. It’s just not beer without yeast. Yeast are also used in many other applications of food production as well. Different yeast strains specialise according to their environment.
A sugar filled wort with nutrients that come from the malted grains combined with the correct temperature is the perfect environment for yeast, the better quality conditions and ingredients will mean the yeast is a lot more effective at converting sugars to alcohol and produces desirable flavours too.
Generally there are two main strains of yeast; ale yeast and lager yeast. Ale yeast are what’s called a top fermenting yeast and work well in warm temperatures between roughly 16°C – 22°C, lager yeasts are bottom fermenting yeasts and work best in cool temperatures 7°C – 13°C.