EFFECTS OF HEAT ON SULFHYDRYL AND DISULFIDE GROUPS OF MILK PROTEINS AS MEASURED BY SPECTROFLUOROMETRIC METHOD

A spectrofluorometric method for the determination of sulfhydryl and disulfide groups in proteins, adapted by our laboratory, has been applied to determine the effects of heat on these groups in milk proteins. These studies revealed that no measurable free sulfhydryl groups are present in native caseins and only limited amounts are generated by high heat treatment. Serum proteins in native form contain a significant amount of free sulfhydryl groups which increased by heat-denaturation at the expense of disulfide in closed systems. In open systems sulfhydryl and disulfide decreased due to volatilization. Heating skimmilk revealed a behavior parallel to serum protein systems. © 1968, American Dairy Science Association. All rights reserved.