Influence of Hsian-tsao Polysaccharide on Structural and Physicochemical Properties of Myofibrillar Proteins in Frozen Surimi and Its Gel Characteristics

Addressing the issue of gel degradation in frozen surimi triggered by protein denaturation, this study employed a conventional commercial cryoprotectant blend (4% sucrose+4% sorbitol) as a control to examine the effects of adding Hsian-tsao polysaccharide HTP (0%, 1%, 1.5%, 2%, 4%, w/w) on the structural and physicochemical properties (including surface hydrophobicity, turbidity, SDS-PAGE profiles, and fluorescence spectroscopy) of myofibrillar proteins (MP) as well as the gel characteristics (including inferred from Fourier transform infrared spectroscopy, electronic tongue analysis, water-holding capacity, gel firmness, and cooking loss) of frozen surimi during 0, 30, and 60 d of storage. The findings demonstrated that, as compared to control, incorporating HTP reduced the surface hydrophobicity and turbidity of frozen MP, inhibiting their aggregation. SDS-PAGE analysed and fluorescence spectroscopy confirmed the efficacy of HTP in alleviating the denaturation and aggregation of frozen MP. Additionally, HTP addition was shown to augment gel strength, enhance water-holding capabilities, and reduce cooking losses, phenomena linked to HTP-induced alterations in protein structure, specifically an increase in β-sheet content and a decrease in surface hydrophobicity. Notably, HTP did not significantly alter the taste attributes (umami, saltiness, and richness) of frozen surimi gels (P>0.05). As HTP increased, the enhancement of gel properties in frozen surimi followed a trend of initial improvement, which then declined. Specifically, after 30 and 60 d of freezing, the gel strength of surimi with 1.5% HTP added increased 2.17-fold and 2.09-fold, water-holding capacity rose by 11.06% and 17.47%, and cooking loss rates diminished by 22.55% and 19.56%, respectively (P<0.05). Concurrently, the surface hydrophobicity of MP declined by 31.84% and 29.43%, paralleled by a decrease in turbidity by 52.81% and 2.43% (P<0.05). Consequently, adding HTP can mitigate the extent of MP denaturation in frozen surimi and improve its gel properties, thereby providing a theoretical basis for the application of HTP in frozen surimi products.