Effects of konjac glucomannan on heat-induced changes of physicochemical and structural properties of surimi gels

•Konjac glucomannan partly sheltered the structure of surimi gels during heating.•Complexes between protein and konjac glucomannan improve the gel structure.•Konjac glucomannan could contribute to the ready-to-eat surimi products.

This work demonstrated the protective effects of konjac glucomannan (KGM) on the physicochemical and structural properties of surimi gels subjected to 120 °C. The T2 relaxation of LF-NMR which was used to detect water mobility, changed more obviously with the addition of deacetylated KGM than with the native, which indirectly implied that deacetylated KGM more pronouncedly influenced the protein structure. Hydrophobic interaction, ionic, hydrogen, and disulfide bonds, were sheltered by deacetylated KGM to greater extent than by native KGM. Raman spectra showed that the reduction of the main random-coil secondary protein structure at 120 °C was more significantly mitigated by deacetylated KGM. The interactions between protein and native or deacetylated KGM were investigated by X-ray diffraction, finding that protein and polysaccharide complexes might be formed. The microstructure of the mixed gels, determined by confocal laser scanning microscopy, demonstrated native and deacetylated KGM helped protein aggregation recover to uniform distribution.

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