Modification of the structural and rheological properties of whey protein/gelatin mixtures through high pressure processing.

High pressure processing (HPP) can induce structure development in macromolecules which are distinct from those of conventional thermal treatments. Gelation properties of whey protein (5-20% w/w) upon 15min HPP at 600MPa and 5 or 30°C (initial sample temperatures) were examined in the presence and absence of 5% w/w gelatin. The values of storage modulus (G') in pressure treated mixed gels were below those of their counterparts thermally treated at 80°C. Mixed systems subjected to HPP in the solution state possessed higher G' than the mixed systems subjected to HPP in the form of gels. The cooling profile of G' in pressurised mixed solutions was similar to that of the gelatin solution, which indicates that HPP resulted in a high degree of gelatin continuity. Confocal images confirmed that gelatin was the continuous phase whilst whey protein aggregated in discontinuous inclusions within the pressurised mixed systems.