Ca2+-Induced Cold-Set Gelation of Whey Protein Isolate Fibrils

Abstract

In this paper we describe the rheological behaviour of Ca2+-induced cold-set gels of whey protein mixtures. Cold- set gels are important applications for products with a low thermal stability. In previous work [1], we determined the state diagram for whey protein mixtures that were heated for 10 h at pH 2 at 80°C. Under these conditions, the major whey protein, β-lactoglobulin (β-lg), forms fibrils. When whey protein mixtures are heated at protein concentrations in the liquid solution regime of the state diagram, cold-set gels can be formed by adding Ca2+ ions at pH 7. We studied the rheological behaviour of cold-set gels for various sample compositions for whey protein mixtures. When keeping the total whey protein concentration constant, the elastic modulus, G’, for the cold-set gels decreased for increasing a-lactalbumin and bovine serum albumin ratios, because less material (β- lg fibrils) was available to form a gel network. In the cold-set gels the interactions between the β-lg fibrils induced by the calcium ions are dominant. The β-lg fibrils are forming the cold-set gel network and therefore determine the gel strength. a-Lactalbumin and bovine serum albumin are not incorporated in the stress-bearing structure of the gels.

Keywords

• cold-set gelation
• whey protein isolate
• b-lactoglobulin
• fibrils