Beer may be defined as the liquid product of the alcoholic fermentation of a wort prepared wholly or mainly from cereal-derived raw material and sugary raw materials, yeast and drinking water, with or without the addition of hops or bitter materials derived from hops and which contain not less than 2 per cent of alcohol by volume at 20oC.
Beer is prepared by fermentation at about 15oC with yeast of a solution of carbohydrates (wort) mainly derived from cereals.
Originally, the principal source of carbohydrate was malted (germinated and dried) barley. However, in view of the high enzyme activity and the high protein content of malt, it has become the practice to use unmalted cereals and cereal preparations with low protein content. These practices have allowed brewers to reduce the cost of materials and to reduce the net protein content of the fermentation liquor with consistent improvement in the stability of the finished beer.
The main types of malt liquors can be classified as follows:
Types of Yeasts used:
Light or Low-Calorie Beer
The wort from which the beer is produced contains about 4% dextrins, which remain in the finished beer and contribute to its calorie content. The yeasts are capable of utilizing the maltose effectively, but cannot ferment the dextrins.
Low-calorie beer can be produced by adding glucoamylase directly to the fermenter. The enzyme hydrolyzes the dextrins, yielding glucose, which can be fermented. Consequently, almost the entire unfermentable carbohydrate fraction is eliminated from the beer while the alcohol content remains the same.
