Gelling properties and structure modification of tilapia skin gelatin by the addition of γ‐polyglutamic acid at different pH levels

Abstract Fish gelatin (FG) has similar functional properties to mammalian gelatin and is a potential mammalian gelatin substitute. However, its poor gelling properties limit its application in many fields. Early on, γ‐polyglutamic acid (γ‐PGA) was found to be effective in improving the gel properties of FG. Therefore, the gelling properties and structure of γ‐PGA to FG under different pH levels were further studied in this article. When the pH of the system is 3, γ‐PGA is positively charged; when the pH of the system is ≥5, γ‐PGA is negatively charged, while FG is positively charged, so the change of the pH of the system affects the electrostatic binding ability of FG and γ‐PGA. A γ‐PGA concentration of 0.04% (w/v) and FG at pH 5 yielded the best gelling properties. Moreover, pH affected the formation of helices during gelatin gelation, and it had a significant effect on the nanostructure of FG. The relationship between structure and physicochemical properties was proposed as a schematic model.