Aggregation Induced by Calcium Chloride and Subsequent Thermal Gelation of Whey Protein Isolate

¹ Department of Food Science, The Pennsylvania State University, University Park 16802

The aggregation of whey proteins that was induced by CaCl₂ was investigated by measuring turbidity and aggregate size. The effect of the aggregation on thermal gelation was determined by measuring gel hardness. Standard conditions were set at 10% whey protein solution, 20 mM CaCl₂, and 45°C in order to observe the influence of different variable levels on the aggregation. The addition of 20 mM CaCl₂ to a 10% whey protein isolate solution resulted in a continuous increase in turbidity during 5 h of incubation at room temperature (21°C). As expected, an increase in temperature (21 to 45°C) or CaCl₂ concentration (5 to 50 mM) increased the rate and extent of the aggregation. Stable colloidal aggregates were formed with 10 to 30 mM CaCl₂. An increase in protein concentration from 5 to 20% remarkably reduced the rate and extent of the aggregation during the 5-h incubation. The aggregation was dependent on the weight ratio of CaCl₂ to whey proteins. Aggregation induced by CaCl₂ before heat-induced gelation greatly affected the hardness of the gels that were formed by heat treatment (80°C for 30 min). The formation of the hardest gels required the optimal extent of aggregation or aggregate size.

Key Words: whey proteins • aggregation • gelation • calcium

Submitted on July 24, 1997
Accepted on November 5, 1997

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