The structure of cold-set whey protein isolate gels prepared with Ca++

The mechanism (s) of Ca2+-induced cold gelation of whey protein isolate was investigated. Kinetic data revealed that the rate constant of aggregation (20 g/L protein, 3 degrees C) progressively increased as [CaCl2] was raised from 10 mmol/L to a maximum of 30 mmol/L, and then declined as [CaCl2] was raised to 120 mmol/L. This could be explained as the combined effect of ch arge dispersion and Ca2+-bridging caused by increasing [CaCl2]. Young modul us increased as protein was raised from 60 to 100g/L w/v at each of the cal cium levels tested (5 to 150 mmol/L). The calculated fractal dimension of t he gels increased from 2.3 to 2.6 as a function of increasing [CaCl2]. This was also observed by scanning and transmission electron micrographs. (C) 1 999 Academic Press.