Chemical modification of New Zealand hoki (Macruronus novaezelandiae) skin gelatin and its properties

Chemical modifications of gelatin from New Zealand hoki (Macruronus novaezelandiae) skins were carried out using three different cross-linking agents, namely, genipin, glutaraldehyde and caffeic acid, at different concentrations. The chemically modified gelatins exhibited better physical properties, such as higher gel strength, melting point, and rheological properties than did the uncross-linked gelatin. Gelatin cross-linked with glutaraldehyde had higher gel strength and melting point (231 g, 21.9 °C) than those cross-linked with caffeic acid (229 g, 21.6 °C) and genipin (211 g, 20.5 °C) at concentrations of 0.133, 0.111, and 0.044 M, respectively. The elastic modulus (G′) and the loss modulus (G″) of chemically cross-linked gelatins were higher than those of the uncross-linked ones. These improved physicochemical properties of gelatin could lead to the development of products in the food industry that meet consumer demands.