Effects of Konjac Glucomannan with a High Degree of Deacetylation on the Gelling Properties of Silver Carp Surimi
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Abstract:
In this study, the effects of Konjac glucomannan (KGM) with a high degree of deacetylation on the gelling propertiesof silver carp surimi were investigated. After different amounts (0.5 wt%, 1.0 wt% and 1.5 wt%) of the deacetylated KGM were added to silver carp surimi, the rheological and textural characteristics, water-holding capacity, relaxation time T2 and microstructural changes of the silver carp surimi were measured. It was found that the elastic modulus G' and loss modulus G" of the composite surimi were higher than those of pure surimi, showing an upward trend with an increase of the amount for addition, and the greatest increase of 27.98% and 49.24% respectively, in G' and G" as compared with the pure surimi gel. The hardness, viscosity and chewiness of the composite surimi gels were significantly higher than those of the pure surimi gel, with the greatest increase as 10.70%, 10.53% and 9.52% respectively, although the elasticity decreased. The results of the low field NMR analysis showed that the peak height of T22 decreased with the peak ratio of T23 increasing for the composite surimi gels, compared to the pure surimi gel. The water-holding capacity showed a downward trend, and reached the lowest value at 0.5 wt% of KGM. The analysis by scanning electron microscopy revealed that the network structure of the composite surimi gels became more complete and orderly. KGM with a high degree of deacetylation affected the thermal aggregation behavior of proteins, promoted the cross-linking of protein molecules and improved the gel network structure, thus, changed the gelling properties of surimi.
