Casein enzymatic coagulation chymosin

Figure 19.3. Sketch of the enzymatic coagulation of casein based on the action of chymosin.

The Daily Industiy. The first step in cheese manufacture is the coagulation of milk. Coagulation can be divided into two distinct phases, enzymatic and the non-enzymatic. In the primary enzymatic phase a proteol ic enzyme such as chymosin (rennet), or less effectively, pepsin, carries out an extremely specific and limited proteolysis, cleaving a phenylalanine-methionine bond of /c-casein, making the casein micelle metastabie. In the second, non-enzymatic phase, the... 

The K-casein provides a layer of hydrophilic polymer at the surface of the micelle that contributes to stability. Removal of the K-casein by enzymatic hydrolysis with chymosin (rennin) results in the micelles eventually undergoing coagulation. This is the principle of cheese making. 

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