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Industrial Microbiology Industrial Microbiology Part 1 Microbial Enzymes and their Uses Solvents Fuels Ethanol Methane Biogas Analytical Microbiology Alcoholic Beverages Ethyl Alcohol Production Beer Manufacturing Wine Manufacturing Distilled Spirits Vinegar Manufacturing Bakers Yeast Production Biofertilizers Food and Fodder Yeast

Beer Manufacturing

	Beer Manufacturing- Beer is made by the yeast fermentation of grains to ethanal and carbon dioxide. There are five major steps in the manufacture of beer or ale from grain. These are malting, mashing, fermenting, maturing, and finishing. Malting and mashing are concerned with the conversion of starch into fermentable form such as maltose or glucose.
The chief raw material is malt, which is germinated barley that has been dried and ground. It contains starch, proteins, and high concentration of amylases and proteinases. Amylases convert the starch into ferm entable sugar. Mould amylase derived from Aspergillus oryzae is sometimes used for the same purpose. Ground malt is mashed in warm water to bring about the digestion of starch and proteins
The aqueous extract contains dextrins, maltose, and other sugars, protein breakdown products, minerals and various growth factors. This is a rich nutrient medium and is called beer wort. The beer wort is filtered arid hops are added, Hops are the flowers of Humulus lupulus. They are added for flavour, colour, and for aroma and for mild antibacterial activity to prevent the growth of spoilage bacteria.
A large inoculum of selected strain of Saccharomyces cerevisiae is added to the wort to bring about a vigorous fermentation. Yeasts are Classified as 'top yeasts' or 'bottom yeast'. Top yeasts float on the surface of a fermenting mixture and are employed in making ale. Bottom yeasts settle in the fermentation tank and are used in making beer. Beer fermentation takes place at 6 to 12°C., whereas ale fermentation is complete in five to seven days at 14 to 23C. The alcoholic content of beer is between 3 to 6 percent that of ale is somewhat higher
	The fermented wort is refrigerated at 0°C for two weeks to several months to remove the harsh flavour and other undesirable characteristics. Some of the harshness attributed to higher alcohols disappears as they are oxidized or esterified during aging. Finishing process consists of carbonation, cooling, filtering and dispensing into barrels, bottles, and cans. Bottled or canned beer is usually pasteurized at 60°C for 20 minutes to kill yeasts and other microorganisms. As an alternative, the beer may be passed through a, filter to remove microorganisms, and then aseptically dispensed into sterile cans.

The composition of American lager beer is as follows: It also contains appreciable amounts of vitamins, particularly, riboflavin. In addition, there are a number of minor constituents, some of which are important for flavour and aroma.

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