Inhibitory effect of different degree of polymerization inulin on the retrogradation of rice starch gels and fresh rice noodles

Abstract

This experiment investigated the effects of inulin (IN) with different degrees of polymerization at various addition levels on the water distribution, textural properties, microscopic and molecular structure, cooking quality, and sensory evaluation of rice starch (RS) and fresh rice noodles (FRN) during storage. The results showed that the addition of three kinds of IN significantly reduced the transverse relaxation time T₂ of the starch gels system during storage, effectively combined the water molecules in the system. Meanwhile, the addition of IN reduced the increase of starch gels hardness during storage, inhibiting the retrogradation of the starch gels. Fourier transform infrared results further confirmed that IN could suppress the retrogradation behavior of starch during storage by controlling the rearrangement or recrystallization of starch molecular chains. The scanning electron microscopy results of FRN after 7 d of storage showed that the addition of IN enhanced the water retention capacity of FRN during the retrogradation process, which was consistent with the water distribution results. Furthermore, all three kinds of IN improved the cooking and sensory quality of FRN during storage, and the lower the degree of polymerization, the better the anti-retrogradation effect and the quality of the FRN.