Evaluation On Color, Eating Quality And Nutrient Of Parboiled Rice

Parboiled rice is one kind of novel rice which is different from milled rice and brown rice not only in processing technology but also in the production itself. Parboiled rice has some outstanding advantages, such as higher head rice yield, higher nutrient content, longer shelf time and more translucent rice kernel than common rice. It is seriously restrict the production and marketing of parboiled rice which accounts for approximately 1/5 of the world’s paddy production in domestic market due to the darker color, increased hardness and decreased stickiness which conflicted with the Chinese consumption customs. Therefore, it can provide reference for popularizing of parboiled rice in domestic market by comprehensive analysis of parboiled rice, especially the color and eating quality.In this research, parboiled rice was prepared with hsien rice through changing the steam condition on the base of technology of parboiled rice. Color, head rice yield, eating quality, structure and nutrient of parboiled rice had been investigated in order to a better understanding of parboiled rice and lay a foundation for the preparation of parboiled rice which meets Chinese consumption customs.Main research results:1. Parboiled rice soaked at 60h℃for 4h, steamed at 100℃for 30min and dried at room temperature had lowest broken rice rate 7.47% which was half of raw rice at the same milling condition. Parboiled rice soaked at 60h℃for 4h, steamed at 100℃for 5min and dried at room temperature had lowest total color difference 0.52 and head rice yield of parboiled rice was 4.85% higher than that of raw rice. Three methods had been employed to determine the color of parboiled rice. Correlation analysis of these data also had been investigated and the results suggested that three methods had significant difference but had good correlation （R²=0.7451, 0.8074 and 0.7518, respective）. Combining the accuracy and rapidness, image analysis had good potential in color determination of food industry. Data from instrument for powder could estimate the surface color of parboiled rice, which is bound up with its’ market value.2. Parboiled rice had lower amylose content than raw rice, and decreased with increasing of steam intensity. The decrease of amylose contents was 4.89% for sample 100-30, which was the largest. The results of TPA and RVA suggested that the hardness increased and the stickiness decreased of cooked parboiled rice. The set back value reduced by about 1/2 which implied the ability of anti-staling improved after cooking. The results of correlation and multiple stepwise regression analysis suggested that TPA and RVA had good correlation, but RVA could not be used for estimating TPA of cooked rice.3. Preliminary structure and nutrient analysis of raw rice and parboiled rice obtained from various treatments had been evaluated. The results of XRD, DSC and SEM showed that the rice starch was partial gelatinized and the intra- and inter- hydrogen bond was breakdown, which lead to the destruction of crystal region, reduction of crystallinity, after soaking and steaming of rice. The gelatinization temperature increased and gelatinization enthalpy decreased due to the starch retrogradation during drying, cooling and storage of parboiled rice. Parboiled rice had higher nutrient than milled rice. The total mineral and the VB₁ content increased. The content of VB₁ for sample 100-30 was about three times than raw rice.