Effects of enriching with gellan gum on the structural, functional, and degradation properties of egg white heat-induced hydrogels.

Gellan gum was employed to modulate the technological functionality and in vitro degradation properties of egg white heat-induced hydrogels at different pH values (4.0 and 7.0). The results showed that the enrichment with gellan gum at pH value of 7.0 did not drastically modify the firmness of egg white gel, but at pH 4.0 the addition of gellan significantly improved the hardness and the compressive stress required for the rupturing of the egg white hydrogels. The enrichment with gellan also modulated the swelling behavior of egg white hydrogels as well as significantly improved their water holding capacity. The scanning electron microscopy (SEM) indicated that the composite gellan/egg white hydrogels formed at pH 4.0 and 7.0 had denser microstructures than the corresponding single-component egg white protein hydrogels. The Fourier transform infra-red (FT-IR) spectroscopy also was used to characterize the interactions between egg white proteins and gellan gum. Furthermore, the results revealed that the enrichment of egg white gels with gellan gum drastically increased their stability against in vitro gastrointestinal degradation which can enhance their applications in the site-specific bioactive delivery.