Ingredients in Beer - Brewing Yeast - Beer YeastBrewing Yeast is one of the main four main ingredients in beer brewing and is also the most essential. Yeast is a unicellular fungus and is also a living organism which possesses the rare ability to live with or without oxygen. In the presence of air, the yeast organisms multiply but in the absence of oxygen, they ferment sugars into alcohol which is what makes beer brewing possible. Ale Beer and Lager Beer are differentiated by the two main types of brewing yeast used to ferment the wort. Wort is the liquid made from water and malt, flavored with hops that is used to make ales or lagers. Ale Beer YeastAle beer yeast is said to be top fermenting since the yeast cells tend to flocculate or gather at the top. Lager yeast on the other hand migrates to the bottom of the tank during fermentation and so is called bottom fermenting. In the case of ale yeast, some interaction with oxygen takes place during fermentation. Ale yeast ferments within a few days to two weeks and at a temperature of around around 21oC/70oF although this can vary from as low as 10oC/50oF to as high as 25oC/77oF . Brews made from it also tend to store longer and have a higher alcohol content. Lager Beer YeastLagers take up to a month to ferment and do so at lower temperatures, sometimes as low as near freezing. Historically, lagers were often brewed in the winter when the air temperature was lower and then consumed later. Temperature ranges vary, though, and can easily be in the higher 45oF-59oF/7oC-15oC range. Along with the advent modern refrigeration came the option of having lager all year round. Lambic YeastThere is also a third type of yeast, called Lambic Yeast, which was originally used almost exclusively in Belgium. The name derives from the West Flanders area in Belgium where Lambic yeasts grow wild. Today, as a result of importing, it is used in many parts of the world. As well as converting malt sugar or maltose into alcohol and carbon dioxide yeast also adds distinctive flavors to the brew during the fermentation process Many ale yeasts have a full bodied, fruity aroma and taste, whilst others possess a more nutty or mineral taste which are more suited to stouts, Belgian ales and other strong brews. One variety is used in Weizen, or wheat beer. The primary ingredient in beer is malt from the cereal grain barley. Wheat beer is not named after the grain used, but after the yeast used to ferment it. Wheat beer yeast goes into this ale style brew, where it helps produce a fruity, intense character. Lager yeasts are usually smoother and dryer, with the taste of cloves, vanilla or a wide variety of other hints. Pilsner, for instance, is a type originating in the Czech Republic in the town of Pilsen from which the brew gets its name. At one time Pilsner formed the basis of 90% of the lagers consumed around the world. But with the increase of micro breweries and the growth of variety in the U.S. and elsewhere, lagers now come as Dortmunders, Marzens, Bocks to name but a few. Though carbon dioxide and alcohol are the two leading products of fermentation, yeast produces secondary products as well. The different types of beer brewing yeast can add tastes or aromas as varied as sweet corn, green apple and butterscotch. The downside is that they can also produce sulfur, or phenolics, which have a medicinal taste. Control of the added flavor is as much an art as the control of fermentation is a science.
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