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The objective of this research was to investigate the effects of deacetylation of konjac glucomannan (KGM) on gel forming ability of threadfin bream (Nemipterus hexodon) surimi gels. Sodium hydroxide solutions with different concentrations (0, 0.01 and 1.0 mol/L) were used for deacetylation of KGM. Different degrees of KGM deacetylation were obtained at 0, 64.08±1.47 and 93.49±1.04 % (D2). Molecular structure of KGM was determined by FT-IR spectroscopy. The result showed that FT-IR spectra of D2 sample was completely disappeared at 1,730 cm-1, which assigned to the group of C=O of acetyl groups. In addition, D2 sample had the lowest solubility and whiteness. Then, different degrees of KGM deacetylation were added to the threadfin bream surimi for comparison with a control (without KGM). It was found that surimi gel with D2 had the highest gel strength, and the lowest expressible water. The microstructure of surimi appeared that the addition of D2 resulted in more compact and uniform microstructures with smaller voids, comparing with the others. SDS-PAGE of surimi with different degrees of deacetylation showed no changes in protein subunit structure from its control gel.
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