Yeast is probably the most important ingredient in beer, in fact without the yeast it could not be beer since it is the yeast which converts the sugars from the malt into alcohol and carbon dioxide along with a few other byproducts which add different tastes to our beer.

The two basic types of yeast are lager and ale but the distinction is becoming more blurred as more craft brewers cross the lines and use ale yeast in traditional lager recipes and vice versa, In fact it turns out that lager yeast is actually a cross between ale yeast and another species which withstands colder temperatures.

There are a great many different "strains" of yeast, in fact most brewers would save some of the yeast from one batch to use in the next. This practice tended to reinforce the good qualities of that yeast strain since the brewer would automatically select for the tastes and features he wanted in his beer.

The byproducts of yeast fall into several types and 3 main categories of taste, diacetyls which give buttery or butterscotch like tastes, esters which provide fruity tastes, and phenols which give spicy tastes or, if too strong, medicinal tastes.

Some of the other byproducts can give off tastes of green apple, corn or cooked vegetables, solvent such as nail polish remover, or sulphur like rotten eggs. Some of these tastes are encouraged in some types of beer while others are usually avoided.

The full range of possible tastes is quite wide and includes apple, bananas, butterscotch, cloves, grass, hay, pear, pineapple, plum, prune, strawberries, and vanilla.

The combinations of different yeasts with the sugars from different malts give an incredibly wide range of taste possibilities. One of the great things about beer is that all these tastes can be selected by the brewmaster to give an endless range of tastes. When the hops are added in to give even more possibilities it is easy to see why beer can be selected to enhance almost any food. More brewmasters in craft breweries are trying out the possibilities all the time. Beer drinking just keeps getting better.