Changing characteristic of surface lipids during rice storage

The surface lipids changes in brown rice and milled rice were studied under thermostatically manual controlled storage condition. The results showed that the content changes and increasing rates of FFA in brown rice and milled rice were different, the FFA of milled rice was higher and increased much more rapidly than that of brown rice. Milled rice had a higher MDA content during storage. The contents of MDA of both kinds of rice declined at the later period of storage under 37℃ and 25℃. The MDA of milled rice (% lipid w/w) decreased much more rapidly than that of brown rice. These showed that milled rice had a large extent of lipids peroxidation than that of brown rice but a bad tolerance of MDA. The Kinetic analysis of FFA changes showed that zero-order kinetics model could likeliest fit the trend of this indicator, and the increase in the value of fatty acids in the aging process with the reciprocal of the absolute temperature change matches the Arrhenius equation. Brown rice is much more stability than milled rice according to its higher Eα of surface lipid hydrolysis reaction.