Interactions between Fish Protein and Soy Protein as Related to Their Gel Forming Properties

Abstract

Interactions between the fish protein and isolated soy protein (ISP) were studied on the basis of heat-induced gel forming property of the mixed systems composed of both proteins. Mixed geis were prepared by heating (90°C, 30min) the homogenized mixtures of the fish paste ("Surimi") and ISP in the presence of 3% NaCl, and when the breaking strength for the mixnd gel deviated from the expected value calculated from those for individual components based on the mixing ratio, this was taken as evidence for the presence of the interactions. As a result, the interactions were dependent on both the protein concentration and mixing ratio of the fish paste to the ISP in the mixed system; below 13% in protein concentration, the synergistic interactions were observed and the deviation in breaking strength from the expected value reached maxmum at the mixing ratio of fish paste to ISP 3:2, e.g., at 11.0% in the protein concentration and this mixing ratio, breaking strength of the mixed-, fish paste-, and ISP-gel were 130, 78.8, and 20.0g respectively. This increase in gel strength caused by mixing both protien materials, that is, the synergistic interaction was interpreted to be related to the promotion in the network formation leading to the building-up of rigid gel body.