Abstract: The structure and physicochemical properties of fermented wheat starch-guar gum (FS-GG) mixtures of wheat starch naturally fermented for 72 h and different proportions of GG (0%, 0.1%, 0.3% and 0.5%, m/m) were studied. The results showed that the addition of GG significantly reduced the amount of leached amylose and the swelling power of FS, and distinctly lowered its peak viscosity and setback value. GG resulted in aggregation of FS granules to form a gel with a tight network structure, and led to an overall increase in the storage modulus (G’) and loss tangent (tanδ). Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results indicated that the addition of GG reduced the degree of order, gelatinization enthalpy and relative crystallinity of FS. The gel firmness of FS-GG mixtures increased slowly during storage. The results of this study indicated that GG delayed the retrogradation of FS by changing its crystal structure and gel structure, and the effect was most pronounced at an addition level of 0.5% GG.

Key words: fermented wheat starch; guar gum; structural changes; physicochemical characteristics