Incorporation effect of inulin and microbial transglutaminase on the gel properties of silver carp (Hypophthalmichthys molitrix) surimi

Surimi-based products with elasticity and specific shapes have received considerable notice in recent years. To ascertain the effects of inulin, microbial transglutaminase (MTGase) and the combination of inulin/MTGase on gel formation of silver carp surimi, the gel strength, textural properties, water-holding capacity (WHC), dynamic rheological measurements, Raman spectroscopy, light microscopy of gel structure and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of gels from different groups were analyzed. The results showed that addition of inulin, MTGase and MTGase + inulin improved gel strength (increased by 7.7%, 26.8% and 38.56% compared with control group), textural properties and WHC. Raman spectroscopy proven that MTGase + inulin promoted the conversion of α-helixes to β-sheets and β-turns compared with other experimental and control groups. Pure surimi gelation contained a loose and non-heterogeneous network via light microscopy. With the addition of MTGase and inulin, the microstructure of surimi gelation became more compact and homogeneous, particularly the MTGase + inulin groups. Moreover, The SDS-PAGE pattern further disclosed that the MTGase + inulin had a weakened myosin heavy chain band, indicating that inulin could enhance the cross-linking effects of MTGase on myosin heavy chains. These data demonstrated inulin incorporating with MTGase may be a new and effective strategy to improve the gel properties of fish surimi.