Coagulation of Skin Milk with Proteases Immobilized on Hydrophobic Carriers

Abstract

Milk-clotting enzymes chymosin and pepsin were immobilized on various hydrophobic carriers (hexyl-substituted Sepharose 6B, phenoxyacetyl cellulose, activated carbon) with an objective to assess their suitability for continuous coagulation of skim milk in cheese production. All enzyme-carrier preparations exhibited high initial activity on exposure to milk. However, deactivation rates were high. The main reason for rapid deactivation appeared to be loss of enzyme from the carriers as soluble activity was detected in most enzyme-carrier preparations. Enzyme loss was from physical desorption of enzyme from the carriers as well as from the relatively rapid leakage of the ligand from the carrier (for phenoxyacetyl cellulose). The best enzyme preparation was obtained with phenoxyacetyl cellulose. However, coagulation of skim milk with proteases immobilized on the hydrophobic carriers used in this study was not economically feasible.