Characterization of the aggregation behavior of sea bass (Lateolabrax japonicus) myofibrillar proteins mediated by different ionic strengths: Protein structures, gel properties, and emulsion stabilities

Ionic strength affects the aggregation behavior and function of myofibrillar proteins (MPs). This study investigated changes in the aggregation behavior and function of sea bass MPs under ion induction to determine the mechanism of its impact. The ionic strength increased the solubility of proteins (up to 90% at 0.6 mol/L), facilitated the transition from alpha-helices to beta-sheets and increased the reactive sulfhydryl groups from 3.12 mu mol/g to 3.93 mu mol/g. The unfolding of MPs ultimately changed their functional properties. Scanning electron microscopy images showed that a gel network structure began to form at an ionic strength of 0.4 mol/L. Furthermore, the water holding capacity and cooking yield of the gel increased from 51.40% to 28.97%-69.01% and 46.16%, respectively, with an increasing ionic strength. The distribution of droplets in the field of view was relatively uniform at an ionic strength of 0.6 mol/L with a minimum value of CI (20.66%). However, the droplets aggregated at higher ionic strengths (>0.8 mol/L), which also decreased the emulsification properties and gel properties. It is hoped that these results will broaden the potential applications of myofibrillar proteins in emulsions and provide guidance for the processing of surimi products.