Enzymes are protein with enormous catalytic activity. They are synthesized by biological cells and, in all organisms, they are involved in chemical reactions related to metabolism. Therefore, enzyme-catalyzed reactions also proceed in many foods and thus enhance or deteriorate food quality. Relevant to this phenomenon are the ripening of fruits, vegetables, meat and dairy products, and the processing steps involved in the making of dough from wheat or rye flours and the production of alcoholic beverages by fermentation technology.
Enzyme inactivation or changes in the distribution patterns of enzymes in sub-cellular particles of a tissue can occur during storage or thermal treatment of food. Since such changes are readily detected by analytical means, enzymes often serve as suitable indicators for revealing such treatment of food. Examples are the detection of pasteurization of milk, beer or honey, and differentiation between fresh and deep frozen meat or fish.
Enzyme properties are of interest to food chemist since enzymes are available in increasing numbers for enzymatic food analysis or for utilization in industrial food processing.
During industrial-scale production, α-amylase is isolated from the pancreatic gland of swine and cattle from microbial culture e.g. the bacterium Bacillus subtilis or the fungi: Aspergillus oryzae. The high temperature-resistant bacterial amylases, particularly that of Bacillus licheniformis are of interest for the hydrolysis of corn starch, (gelatinization at 105-110 degrees C).
α-amylase is utilized in the baking industry and in the production of starch derivatives. In addition, studies are being conducted in several countries in which malt will be partially replaced by α-amylase and other enzymes of microbial origin, in the production of beer and spirits.
During the malting of cereals, such as barley, β-amylase is bio-synthesized to a greater extent than its counterpart, α-amylase. Because of the presence of these enzymes, malt is used extensively in processes where saccharification of starch is required.
There are three types of pectic enzymes: pectinesterase, polygalacturonase and pectin lyase although the last is not used commercially. Commercially the endo polygalacturonase is more useful as it produces more rapid depolymerization. Fungal enzyme preparations, consisting of polygalacturonase, pectin methylesterase, cellulase, hemicellulaseand protease, are used: (1) to accelerate rates of filtration of fruit juices, (2) to remove pectin from fruit base prior to gel standardization in jam manufacture, (3) to prevent undesirable gel formation in fruit and vegetable extracts and purees, (4) to standardize the characteristics of pectin for the varied uses as a thickener, (5) to recover citrus oils, and (6) to stabilize cloud in fruit juices
