Rennin sources

Several workers have chemically modified milk proteins ( c-casein, casein) to determine the chemical basis for the stabilization of the casein micelle by c-casein and to elucidate the mechanism of rennin action (35,36). Creamer et al. (37) made several derivatives of sodium caseinate and showed their improved solubility. In preliminary feeding trials in which succinylated casein was the only protein source, supplementation with lysine was required for the normal growth of rats. 

Source. Enzymes for food applications come from all three kingdoms plant, animal, and microbial. Traditionally used plant and animal enzymes are the plant proteases such as papain, ficin and bromelain, plant amylases from malt, and animal rennin which is used in cheese manufacture. Microbial cells are the usual and most promising future source of industrial enzymes. Estimates of the number of microorganisms in the world tested as potential sources of enzymes fall around 2% with only about 25 organisms, including a dozen or so fungi, currently used for industrial enzymes. 

Leaching or solid-liquid extraction are terms that describe the extraction of soluble constituents from a solid or semisolid by means of suitable solvents. The process, which is used whenever tea or coffee is made, is an important stage in the production of many fine chemicals found naturally in animal and vegetable tissue. Examples are found in the extraction of fixed oils from seeds, in the preparation of alkaloids, such as strychnine from Nux vomica beans or quinine from Cinchona bark and in the isolation of enzymes, such as rennin, and hormones, such as insulin, from animal sources. In the past, a wider importance attended the process because the products of simple extraction procedures, known as galenicals, formed the major part of the ingredients used to fulfill a doctor s prescription. 

A proteolytic enzyme secreted by gastrie mueosa of infants is chymosin (rennin), which functions to clot milk and promote its digestion by preventing rapid passage from the stomach. Chymosin hydrolyzes casein, a mixture of several related milk proteins, to paracasein, whieh reacts with Ca + to yield the insoluble curd. Pepsin performs the same funetions as chymosin. Chymosin is found in the fourth stomach of ruminants. Calf stomach is a source of this enzyme, which is used in the manufacture of cheese. Chymosin has been synthesized by recombinant DNA techniques and successfully used in the produetion of cheese. 

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