Reversible Gelation of Whey Proteins: Melting, Thermodynamics and Viscoelastic Behavior

Abstract

Whey protein isolates formed reversible gels following heating at 9(PC for I5 min under certain conditions i.e., pH 6.5 to 8.5 with protein concentration of 9.0-10.5%. The melting temperatures of the gels formed at pH 8.0 ranged from 24.5"C to 57.8"C. The maximum enthalpy of formation (nHJ was -858 call mole of crosslinks. A maximum storage modulus ( G I ) of 240 dyneslcm2 was obtained following holding for 7 h at 8°C.

Viscoelastic Properties of Whey Protein Gels: Mechanical Model and Effects of Protein Concentration on Creep

“…This may indicate a number of polymer-polymer and polymer-solvent interactions and may reflect their relative importance in stabilizing the gel network at the different temperatures. Beveridge et al (1984), discussed whey protein gel systems as being composed of thermally reversible and nonreversible networks and recently we have described conditions for forming reversible WPI gels (Rector et al, 1989).…”

“…The stabilization of the network formed from whey protein isolate gels involves a significant enthalpic contribution (Rector et al, 1989;Beveridge et al, 1984). Both intra-and intermolecular noncovalent interactions occur and prevent the formation of long random coils between networks in these WPI gels.…”

Improvement of protein gel by physical and enzymatic treatment

“…Some exceptions are reported. Arachin (17) and milk whey protein isolate (18) can give heat-reversible gels, with a gel-sol transition, and the thermal coagulation of an egg white solution was prevented when the coagulum formed by prior foaming treatment was removed (19). The preparation of egg white that did not give a coagulum upon heating has been reported (19).…”

Disulfide-Mediated Polymerization of Whey Proteins in Whey Protein Isolate-Stabilized Emulsions

“…In this dissociated form the free thiol group is exposed and can engage in intraor intermolecular thiol-disulfide interchange reactions (Dunnill and Greene, 1966). Unfolding ofP-Lg induced by heat (Rector et al, 1989;Matsudomi et al, 1992), denaturants (Xiong and Kinsella, 1990) or by its use as an emulsifier can also promote thiol-disulfide interchange.…”