Influence on the physicochemical properties of fish collagen gels using self-assembly and simultaneous cross-linking with the N-hydroxysuccinimide adipic acid derivative

Abstract

Collagen gels from Southern catfish (Silurus meridionalis Chen) skins were prepared via the self-assembly of collagen molecules and simultaneous cross-linking with the N-hydroxysuccinimide adipic acid derivative (NHS-AA). The doses of NHS-AA were converted to [NHS-AA]/[NH₂] ratios (0.025–1.6, calculated by the [active ester group] of NHS-AA and [ε-NH₂] of lysine and hydroxylysine residues of collagen). When the ratio < 0.05, collagen gels were formed by collagen molecule self-assembly, resulting in the opalescent appearance of collagen gels and the characteristic D-periodicity of partial collagen fibrils, the collagen gel ([NHS-AA]/[NH₂] = 0.05) displayed a small increase in denaturation temperature (T_d, 42.8 °C), remaining weight (12.59%), specific water content (SWC 233.7) and elastic modulus (G′ 128.4 Pa) compared with uncross-linked collagen gel (39.1 °C, 9.12%, 222.4 and 85.4 Pa, respectively). As the ratio > 0.05, disappearance of D-periodicity and a gradual change in appearance from opalescent to transparent suggested that the inhibition of NHS-AA in the self-assembly of collagen molecules was more obvious. As a result, the collagen gel ([NHS-AA]/[NH₂] = 0.2) had the lowest T_d (35.8 °C), remaining weight (7.96%), SWC (130.9) and G′ (31.9 Pa). When the ratio was 1.6, the collagen molecule self-assembly was markedly suppressed and the formation of collagen gel was predominantly via the covalent cross-linking bonds which led to the transparent appearance, and the maximum values of T_d (47.0 °C), remaining weight (45.92%) and G′ (420.7 Pa) of collagen gel. These results indicated that collagen gels with different properties can be prepared using different NHS-AA doses.

• Collagen gel
• cross-linking
• N-hydroxysuccinimide adipic acid derivative Southern catfish
• properties
• self-assembly

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

This work was funded by the National Natural Science Foundation of China (Nos. 21276167 and 21476147).

Notice of Correction

Changes have been made to this article since its original online publication date of 9 March 2015.