Effect of Rice Yellowing on Sulfuric Acid Hydrolysis of Rice

In this paper, the structural differences between the two rice varieties were studied after sulfuric acid hydrolysis, the samples were immersed in 0.1, 0.5, 1.0 mol/L sulfuric acid solution for 72 h, the thermodynamic, crystallization and structure properties were measured. The results showed that the yellowing process leads to a decrease of ΔT in thermodynamic properties, under the condition of 1 mol/L sulfuric acid treatment, the gelatinization temperature range of Indica PHY rice was 45.64℃, the gelatinization temperature range of Indica normal rice was 61.26℃, the gelatinization temperature range of japonica PHY was 47.46℃, and the gelatinization temperature range of japonica normal rice was 50.95℃. The results of XRD and SAXS showed that the amorphous background area of amylose and the amorphous layer of amylopectin inside the rice were destroyed after sulfuric acid hydrolysis, and the higher the acid solution concentration, the more the amorphous area inside the rice was destroyed. Under the 1.0 mol/L sulfuric solution treatment, the semi-crystalline layer of PHY were rearranged and the structure tended to be orderly. The apparent structural results showed that PHY has a more loosed structure than ordinary rice after acid hydrolysis.