Thermal Properties of Whey Protein Aggregates

¹ Department of Food Science, The Pennsylvania State University, University Park 16802
² Department of Food Science, University of Arkansas, Fayetteville 72704

Aggregation of 10% whey protein solution was induced by addition of calcium salt, acidification, or proteolysis at 45°C. Effects of the preaggregation on thermal properties of whey proteins were examined by differential scanning calorimetry. The different types of aggregates had three common effects: 1) one endothermic peak, representing denaturation of whey protein aggregates, instead of two endothermic peaks representing alpha-lactalbumin and beta-lactoglobulin in the control; 2) a narrower range (10°C) of denaturation temperature than the control (20°C); and 3) significantly greater enthalpy values (4 J/g) than the control (<2 J/g). Denaturation temperatures (T_D, T₀) of the aggregates were also different from those of alpha-lactalbumin (67°C) and beta-lactoglobulin (76°C) of the control. Aggregates induced by calcium salt (74°C) and protease (73°C) had intermediate denaturation temperatures. The pH-induced aggregates had high denaturation temperatures (80 to 91°C) at low pH (3.5 to 5.7). An exothermic peak was detected during calcium salt- or protease-induced aggregation of whey proteins at 45°C. Thus, the pre-aggregation changed thermal properties of whey proteins. This information on thermal properties of the aggregates may help in the design of appropriate heat processing for the application and manufacture of whey protein products.

Key Words: whey proteins • aggregation • differential scanning calorimetry • denaturation

Submitted on January 11, 1999
Accepted on May 17, 1999

This article has been cited by other articles:

				Q. Zhong and M. Jin Enhanced Functionalities of Whey Proteins Treated with Supercritical Carbon Dioxide J Dairy Sci, February 1, 2008; 91(2): 490 - 499. [Abstract] [Full Text] [PDF]