Composite cold-set gels of kidney bean protein isolate and basil seed gum induced by glucono-δ-lactone and sodium citrate: Preparation, gel properties and protection on astaxanthin.

In this study, kidney bean protein isolate (KPI) and basil seed gum (BSG) thermal aggregates were prepared to form cold-set gels (KB) by adding sodium citrate (SC) and glucono-δ-lactone (GDL). The structure and gel properties of the cold-set gels were investigated. Results showed that the gels added with SC had higher water holding capacity and lower gel strength than GDL-induced gels. While the cold-set gels induced by GDL with the addition of SC (KB-GDL/SC) possessed compact gel network with higher viscoelasticity. Compared with KPI cold-set gels, the KB cold-set gels exhibited higher gel strength and greater capacity to capture water due to the filling and cross-linking effect of BSG, and its high hydrophilicity and changes on the KPI molecular structures. Moreover, the KB-GDL/SC presented a lower syneresis rate of 28.2 % than other gels after freeze-thaw treatment. Meanwhile, KB-GDL/SC showed better protection on astaxanthin under ultraviolet light or during heat treatment. All the KB cold-set gels controlled the release of astaxanthin during simulated digestion. Particularly for KB-SC, the loaded astaxanthin had the highest bioaccesssbility (24.5 %) after in vitro digestion. This study may provide unique insights for development of novel cold-set gels and related functional foods.