关键词: 麦麸多糖, 鱼糜, 凝胶特性, 水分状态, 二级结构, 微观结构

Abstract:

【Objective】This study aimed to investigate the impact of wheat bran polysaccharide on the physical properties and microstructure of surimi gel, and to elucidate the mechanism by which the concentration of wheat bran polysaccharide affects surimi gel characteristics, so as to provide the theoretical support for enhancing surimi gel quality through the utilization of wheat bran by-products.【Method】Different concentrations of wheat bran polysaccharide were added to threadfin bream (Nemipterus virgatus) surimi to prepare composite gels. The effects of wheat bran polysaccharide on the characteristics and structures of surimi gel were investigated using texture analysis, rheological test, molecular interaction measurement, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM).【Result】The impact of wheat bran polysaccharide on the macroscopic physical properties and microstructures of surimi gel exhibited a pronounced concentration dependence. As the amount of wheat bran polysaccharide increased, the rheological parameters (G' and G" values), water holding capacity, texture profile analysis (TPA) values, gel strength, and water distributions of the blended system were all initially elevated and then declined, achieving the maximum improvement at the addition level of 1.0%. FTIR revealed that the secondary structure of proteins during the heat-induced gelation of surimi was closely related to the polysaccharide content: with increasing polysaccharide content, the α-helix content gradually decreased, while β-turn and β-sheet content showed an upward trend (P<0.05). However, when the polysaccharide addition exceeded 1.0%, the α-helix content gradually increased again, while β-turn and β-sheet content exhibited downtrends. This may be due to the concentration-dependent effect of polysaccharides on the disulfide bonds and electrostatic interactions, which were the primary intermolecular forces within the protein gel, leading to the changes in its secondary structure. SDS-PAGE electrophoresis showed that when the polysaccharide addition was over 1.0%, the actin (AC) and myosin heavy chain (MHC) bands became significantly lighter, with dark bands accumulating at the top of the stacking gel. SEM observations of the microstructure of surimi gels revealed that as the polysaccharide added, the pore size within the surimi gel network gradually reduced. When the polysaccharide addition reached 1.0%, the surimi gel network structure was the most compact, with the fractal dimension (D_f) reaching a maximum value of 2.8657. Further addition of the polysaccharide leaded to phase separation in the gel system, and extensive self-aggregation of polysaccharides disrupted the surimi protein gel network, resulting in a decrease of D_f.【Conclusion】Wheat bran polysaccharide with the concentration of 1.0% to the surimi could be used as a filler as well we water retention agent in the three-dimensional network structure of surimi protein, and induce the formation of a more uniform and dense gel matrix, which could effectively improve the gel quality of surimi.

Key words: wheat bran polysaccharide, surimi, gel characteristics, water status, secondary structure, microstructure