The Effects of Grass Carp Skin Gelatin and Whey Protein Interactions on Rheological and Textural Properties and Nanostructure

The physical properties and nanostructure of fish skin gelatin with and without whey protein isolate (WPI) were investigated. The addition of low concentrations of WPI (1 and 3%, w/v) into fish gelatin decreased the gel strength and textural properties. The addition of 5% WPI did not significantly influence textural properties but increased the melting and gelling temperatures of fish skin gelatin and improved the appearance of gelatin gels. X-ray diffraction indicated that a higher degree of crystallinity with an ordered structure or ordered structure snippets occurred with increasing WPI concentrations in line with the slight decrease in the loss factor (tan δ) with time sweeps. Fish gelatin had a spherical nanostructure, and a homogeneous nanostructure was observed in gelatin with 3% WPI. The addition of 5% WPI led to large aggregates in gelatin gels. The results indicated that whey protein could affect the nanostructure of fish skin gelatin gels and thus change their gelation properties and texture in food and pharmaceutical applications.