| Rice aging is a complex process that involves changes in the physicochemical properties of rice.In this paper,three rice varieties(Japonica rice:NG,Indica rice:YD,hybrid rice:YY)were used as research objects to explore the effects of rice aging at different storage temperatures and different times on the molecular structure and physicochemical properties of rice.After storing rice samples at-20℃,4℃,room temperature(20-25℃)and 40℃ for 30 days,100 days and 200 days,the preliminary physical and chemical quality determination results showed that:1.Effect of different storage temperature and storage time on the component content of rice samples:the protein content and total starch content in the three rice samples decreased slightly,and the crystallinity decreased with the increase of aging time,and different aging temperatures and aging times did not affect the crystal type.2.Effects of different storage temperature and storage time on the molecular structure of rice samples:the fine structure of starch was measured by FACE and SEC,and the results showed that the length distribution of starch pullulan chain length of starch during rice storage and aging did not change significantly.3.Effect of different storage temperature and storage time on the physical and chemical properties of rice samples:DSC results show that after 200 days of storage,the gelatinization start temperature(To),peak temperature(Tp),and end temperature(Tc)and enthalpy change(ΔH)of the three samples have decreased to varying degrees compared with the early stage of storage,and no matter what kind of changes the samples have been stored under different conditions during storage,the enthalpy change(ΔH)of the samples at different storage temperatures will tend to be approximated after long-term storage.RVA results showed that the effect of storage time on the gelatinization characteristics of rice samples was less than that brought by storage conditions,and rice starch granules stored under high temperature conditions were more prone to swelling,and the samples stored under high temperature conditions had higher viscosity than samples stored under low temperature conditions,which also proved that the degree of aging of rice stored under high temperature conditions was higher than that of samples stored at low temperatures.The TPA results showed that the hardness of all three samples increased with the increase of storage time,and the hardness of the samples aged at high temperatures was higher.The results of in vitro digestion showed that the final digestibility of the three samples also increased significantly at the beginning of storage(0-3 0D),and then fluctuated slightly,and the digestion rate of the three samples decreased after 200 days of aging at 40℃,which showed that long-term storage under high temperature conditions would affect the digestion rate of rice. |
