Effect of yeast β-glucan on gel properties, spatial structure and sensory characteristics of silver carp surimi

Effect of yeast β-glucan (YG) at different contents on gel properties, spatial structure and sensory characteristics of silver carp surimi was investigated by texture analysis, magnetic resonance imaging (MRI), light microscopy with eosin staining and sensory evaluation. The 2%YG addition dramatically improved the water-holding capacity (WHC), hardness, springiness, chewiness and gel strength of surimi gel. According to stress relaxation fitted by three-element model, YG addition shortened relaxation time (τ) and increased equilibrium and decay elastic coefficient (E0 and E1) of surimi gel, suggesting an increasing hardness and elasticity and a decreasing viscosity. When YG added, a part of free water transferred into immobile water and the gel surface had more water than the intermediate portion. In surimi/YG gels, YG formed approximately circular voids and uniformly dispersed in continuous network of surimi matrix. As YG increased (0–2%), YG competed with surimi for water, which caused effective concentration of surimi protein increased and gel-forming ability enhanced. Next, the water-absorbing and swelling YG exerted pressure on surimi matrix and caused the matrix more compact and firm. Besides, YG as semi-rigid fillers filled the interspace between protein network to reinforce its structure. However, with a further increase in YG (3–5%), the number and size of voids formed by YG drastically increased, and excess YG instead of surimi could not compensate for the decrease in surimi gel-forming ability, but hinder cross-linking of proteins in surimi to weaken, even disrupt continuous network of surimi matrix. Additionally, YG reduced off-odor from freshwater fish and remained fish delicious taste.