Rheological Properties of Water-Soluble Protein from Fish and Improvement of Functional Properties

Abstract

The effective utilization of water-soluble protein （WSP） from fish that is discarded with waste water during seafood processing is an important challenge for the establishment of sustainable ocean ecosystems and efficient use of unused resources. This review men tions the rheological properties of WSP and their improvement by the addition of other kinds of food proteins and fatty acid salts. Original dilute WSP was concentrated using a hydrophilic polymer derived from sugar. The rheological properties of water-soluble protein concentrate （WSPC） of fish meat were examined with other kinds of protein, such as ovalbumin （OVA） or β-lactoglobulin （β-LG）, and fatty acid salt. The OVA-WSPC or β-LG-WSPC mixture formed a homogeneous gel in the presence of sodium caprate, which is one kind of fatty acid salts. The secondary structure of the proteins was also investigated using Fourier transform infrared spectroscopy （FT-IR）. The α-helix and intramolecular β-sheet structures in the mixed protein were reduced and the intermolecular β-sheet structure was increased by the addition of sodium caprate. These results suggest that WSPC could contribute to changing properties of the fatty acid salt-induced mixed protein gel as a texture modifier. A further topic is the preparation of an edible film using WSP from blue marlin meat.