Whey protein gels aggregation

Altrng, A.C., Hamer, R.J., Kruif de, C.G., Paques, M., and Visschers, R.W. (2003). Number of thiol groups rather than the size of the aggregates determines the hardness of cold set whey protein gels. Food Hydrocolloids 17,469-479. 

In the case of cold-induced aggregation and gelation, two different types of gel microstructure, namely filamentous and particulate (Figure 2.1), have been obtained by adding different concentrations of a ferrous salt to solutions of pre-denatured p-lactoglobulin (the major whey protein). This substantial difference in microstructure turns out to have a major impact on the iron delivery, due to the different sensitivities of the structures to the relevant environmental conditions, such as pH and the presence of digestive enzymes. In particular, the filamentous gel micro-... 

When milk at a pH of less than 6.5 is heated for 20 to 30 min at 100°C, it coagulates to form a gel. Casein micelles isolated from such milk have denatured whey protein attached to micelle surfaces (Creamer et al. 1978). Such micelle surfaces aggregates of whey pro-... 

Enzymatic gelation of partially heat-denatured whey proteins by trypsin, papain, pronase, pepsin, and a preparation of Streptomyces griseus has been studied (Sato et al., 1995). Only peptic hydrolysate did not form a gel. The strength of the gel depended on the enzyme used and increased with increasing DH. Hydrolysis of whey protein concentrate with a glutamic acid specific protease from Bacillus licheniformis at pH 8 and 8% protein concentration has been shown to produce plastein aggregates (Budtz and Nielsen, 1992). The viscosity of the solution increased dramatically during hydrolysis and reached a maximum at 6% DH. Incubation of sodium caseinate with pepsin or papain resulted in a 55-77% reduction in the apparent viscosity (Hooker et al., 1982). 

Denaturation and aggregation caused by heat treatment will be discussed for two completely different protein systems namely a soy and a whey protein system. Although the two protein systems are different in character they both have the ability to form a gel after heat treatment. 

Mleko, S. and Foegeding, E. A. 2000. pH induced aggregation and weak gel formation of whey protein polymers../. Food Sci. 65 139-143. 

An alternative approach to the formation of whey gels is to predenature whey proteins under carefully controlled conditions to form aggregates, followed by cold gelation in the presence of salts (Bryant and McClements,... 

Blends of whey protein isolate and denatured whey protein isolates were microparticulated using a microfluidizer prior to the formation of heat-set gels. Increasing the number of passes in the microfluidizer increased the hardness of the gels, an effect attributed in part to the more homogenous gelation of smaller aggregates (Sanchez et al., 1999). 

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