DENATURATION AND AGGREGATION OF SERUM-PROTEINS AND CASEINS IN HEATED MILK

Skimmed milk was heated in a specially constructed apparatus for times between 1 and 20 min, at set temperatures in the range 75-90 °C. The extent of denaturation and loss of the serum proteins, principally β-lactoglobulin, was estimated by gel filtration chromatography in nondissociating buffers. The amount of aggregated β-lactoglobulin/k-casein complex was estimated by gel filtration in buffer that dissociated all micellar components apart from those which were linked by disulfide bonds. The results demonstrated that β-lactoglobulin denatured by a pseudo-first-order process and that there was a direct relationship between the formation of aggregate and the amount of serum protein lost. Only disulfide-linked polymers were necessary to explain the products formed during heating in this temperature range. © 1990, American Chemical Society. All rights reserved.