Multivariate analysis of the influences of locust bean gum, α s-casein, κ-casein on viscoelastic properties of Na-K-carrageenan gels

Abstract

A full factorial experimental design, with five design variables, was used to study the viscoelastic effects of α s-casein, κ-casein and locust bean gums with two different mannose to galactose ratios on Na-κ-carrageenan gels in 0.25 M NaCl. Dynamic viscoelastic measurements were performed during cooling, 1 h storage at 15 °C and re-heating. This study demonstrates the potential of using multivariate methods when evaluating the effect of different constituents on the viscoelastic properties of a multicomponent bio- polymer mixture. Partial least square regression shows that it is possible to obtain a relation between the storage modulus ( G′) and the concentration of the polymers in the mixture. Evaluation of the models obtained during the course of gelation, storage and melting shows that the G′ of the κ-carrageenan system is predominantly influenced by locust bean gum with a high mannose to galactose ratio. Significant co-operative concentration effects were observed for κ-carrageenan in combination with the locust bean gums. No co-operative concentration effects were observed between the caseins and the locust bean gums, which suggests that the effects of these can be evaluated separately. α s-Casein influences the G′ in the initial state of gelation, whilst κ-casein shows effects after gel formation. The gelation and melting temperatures of the κ-carrageenan system, measured by rheology, were influenced by addition of locust bean gum, α s-casein and κ-casein. Measured thermal hysteresis was increased and shifted to higher temperatures