Rheology of Milk Gels Formed by Milk‐clotting Enzymes

Clotting times and complex rigidity moduli (G) were determined with a thrombelastograph during clotting of skim milk by soluble and immobilized pepsin and during rennet‐clotting of milk acidified with various acids to pH 5.6. Longer clotting times resulted in slower rates of increase in G; excellent linearity existed between the two factors for clots formed by immobilized and soluble pepsins. For these two enzymes, the approach of G to maximum G was first order with respect to time during most of the clot formation. The type of acid greatly affected G but not clotting time except that samples acidified with citric acid clotted slower. Acids effecting higher G in gels also cause greater retention of calcium in cheese.