Abstract:Starch retrogradation is the main contributor to quality deterioration of chilled rice during storage. To clarify the influence of fructooligosaccharides on the quality of chilled rice, the effects of adding different mass fractions (1%, 2%, 3%, and 4%) of fructooligosaccharide on water absorption by soaking rice, and fraction-dependent effects on the texture, taste value, and iodine blue value of rice after cooking were studied. Rice microscopic morphology was observed through scanning electron microscopy. Differential scanning calorimetry, Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction were employed to analyze the mechanism by which fructooligosaccharides influence rice retrogradation. After soaking in 1% (m/m) fructooligosaccharides for 15 min, the water absorption rate of rice reached 17.60%, representing a significant increase of 11.69% compared with that of the control group (P<0.05). After storage for 7 days, the hardness of rice treated with 1% fructooligosaccharides significantly reduced by 13.17% compared with that of the control group. Taste was best preserved with 1% fructooligosaccharide treatment. Compared with those of the control group, the enthalpy of regeneration and relative crystallinity of the 1% fructooligosaccharide treatment group were lower. The FT-IR ratio of 1 047/1 022 cm-1 in the infrared spectrum decreased from 1.07 to 1.02. The treated rice exhibited a more compact and dense microstructure and improved retrogradation resistance compared with the control rice. In short, fructooligosaccharides maintained the quality of chilled rice and inhibited starch recrystallization. This study provides data supporting the application of fructooligosaccharides in delaying the retrogradation of starch-based products.
