Kinetics of gel forming in enzyme coagulated milk.
A semi-empirical kinetic model has been developed to explain the observed kinetics of gel formation in enzyme coagulated milk. The kinetic model assumes that the actual system can be represented by a two-step reaction in series model in which both reactions are first order.The initial reaction is the formation of potential cross-link points corresponding to the hydrolysis of K-casein which covers the surface of casein micelles. The second reaction is the formation of cross-links between casein micelles as individual micelles interact with each other. The initial reaction is dependent on the concentration of enzyme in the solution, while the second reaction is enzyme independent. The formation of increasing numbers of cross-links results in an increase in the shear modulus of the gel. The model correctly predicts the general shape of the shear modulus vs. time curve, and faithfully accounts for the influence of enzyme concentration of the rate of shear modulus increase. It is also consistent with the influence of pH and temperature, and denaturation on the activity of the enzyme for the range of these values tested.
Carlson
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The Pennsylvania State University Chemical Engineering Department University Park, PA 16802.