The Hofmeister series: Anion effect on microbial transglutaminase cross-linked soybean protein isolate hydrogels.

In this paper, the possibility of the kosmotropic anion (CO, Citrate, SO, HPO, CHCOO and Cl) to improve the gel properties of microbial transglutaminase (MTG)-crosslinked soybean isolate protein (SPI)-based hydrogels was explored using a soaking strategy. The results of this experiment demonstrated that the hardness of the hydrogel undergoes different degrees of enhancement after different salt treatments in the following order: HPO > CHCOO > SO > Citrate > Cl > CO. Rheological results showed that salt treatment led to enhancement of the energy storage modulus of the hydrogels. Further experiments indicated that the water-binding capacity of different salts depended on the salting out effect. Based on the Hofmeister effect, hardness-enhanced SPI-based hydrogels were successfully prepared. The Hofmeister effect offers a simple, an effective and a novel method for the preparation of functional SPI hydrogels.