Characterization of the gelation and resulting network of a mixed-protein gel derived from sodium caseinate and ovalbumin in the presence of glucono-$\delta$-lactone

TL;DR

This study characterizes the gelation behavior of mixed sodium caseinate and ovalbumin proteins using various techniques, revealing how protein ratios influence gel properties and network structure.

Contribution

It provides new insights into the gelation mechanisms of mixed proteins and demonstrates the use of confocal microscopy to analyze protein networks.

Findings

Increasing ovalbumin decreases gel mechanical strength.

Ultrasound changes during gelation are smaller than heat-induced gels.

Sodium caseinate mainly forms the gel network.

Abstract

We investigated mixed-protein gels made from sodium caseinate and ovalbumin at different ratios with use of the acidification agent glucono-$\delta$-lactone. Dynamic viscoelastic measurements revealed that increasing the ovalbumin content decreased the mechanical properties of the gel but accelerated onset time of the phase transition. Ultrasound spectroscopy during gelation revealed that the relative velocity gradually decreased, whereas the ultrasonic attenuation increased during the whole acidification process until gelation was complete, although these changes were much smaller than those observed with heat-induced gelation. Confocal laser scanning microscopy along with scanning electron microscopy revealed that although uniform mixing of sodium caseinate and ovalbumin was observed, sodium caseinate is likely to mainly lead formation of the gel network, and the porosity of the resulting gel network depends on the ratio of these two components. The results demonstrate that confocal laser scanning microscopy is a useful tool for analyzing both the networks within mixed-protein gels and the contribution of each protein to the network and gelation.