Studies On Nutritional Ingredients, Modification And Application Of White Rice Bran

In this paper, the distribution of the main nutritional ingredients and five kinds of mineral elements in each stage of brown rice whitener was studied firstly. According to the property of the rice bran in third stage and using it as raw material, the enzymatic hydrolysis technology to product dextrin was studied. Then the process of modification of dextrin to prepare octenyl succinate dextrin ester and some properties of products was studied. Meanwhile, the application in microencapsulation of oil for modified product of white rice bran was discussed. The main results were as follows:1. The disposition of main nutritional ingredients and five kinds of mineral elements of the different rice samples and rice bran in each stage of rice whitener were studied. The results show that brown rice had more nutritional ingredients and mineral elements than polished rice; the components of rice bran from different procedures were different, the rice bran in first and second stage were abundant in oil and protein, and the rice bran in third stage were rich in starch and low in fat; Brown rice cortex contained more abundant mineral elements which much lost to rice bran with the increased precision of grinding white; the rice bran in first stage had the most mineral elements, and the content of Mg and Ca were in the majority in rice; the order of the content of five kinds of mineral elements was Mg>Ca>Zn>Fe> Cu.2. The process of using medium temperature amylase to hydrolyze starch was studied, taking white rice bran as raw material and the hydrolysis degree (DE) as evaluation index. Based on single-factor experiments, the enzymatic hydrolysis was optimized by orthogonal test. The optimal parameters were reaction temperature 70℃, the ratio of material to water 1:8, enzyme concentration 20U/g, reaction time 20min, and the hydrolysis degree of starch hydrolyzate under this condition was 21.52. Range analysis of orthogonal experiments showed that the sequence of the factors affecting the hydrolysis degree of starch was as follows:enzyme concentration> reaction temperature> reaction time> the ratio of material to water.3. The preparation process of octenyl succinate dextrin ester was studied, taking self-made dextrin as raw material and degree of substitution (DS) as evaluation index. Based on single-factor experiments, the preparation process of octenyl succinate dextrin ester was optimized by orthogonal test. The optimal parameters were the mass fraction of substrate 45%, reaction temperature 35℃, pH 8.5, reaction time 4.5h, and the degree of substitution of the product under this condition was 0.0196. Range analysis of orthogonal experiments showed that the sequence of the factors affecting the degree of substitution of the product was as follows:mass fraction of substrate> pH> reaction temperature> reaction time.4. The structure and some properties of octenyl succinate dextrin ester were studied. The results show that there were new absorption peaks at 1735.65cm"1 and 1573.64cm-1 in the infrared spectrum of octenyl succinate dextrin ester, compared with infrared spectrum of dextrin. It proved the existence of ester carbonyl. That is to say, the esterification happened between dextrin and octenyl succinic anhydride. The octenylsuccinate groups were introduced into dextrin molecules by esterification. The apparent viscosity of dextrin modified was higher than native dextrin, but the former of dextrin modified still displayed shear thinning phenomenon and belonged to pseudoplastic fluid. In the same concentration, the transmittance of octenyl succinate dextrin ester was lower than dextrin. And with the concentration increasing, the transmittance of them showed a decreasing trend. The freeze-thaw stability and emulsion of dextrin modified were improved.5. The formula and emulsification process of preparing the nutritional powdered oil with refined white rice bran as raw material were determined. The amounts of compotents in the formula were as follows:octenyl succinate dextrin ester was 12%, corn syrup was 35%, the suspension of refined white rice bran was 21.2%(dry matter content), soybean salad oil was 30%, poly glyceride was 1.8%. Two-phase emulsification was applied and the condition of emulsification process was as follows:the water phase temperature was 75℃, the oil phase temperature was 65℃, homogenizing pressure was 30MPa, homogenizing third. At last, the nutritional powdered oil with refined white rice bran as raw material was prepared by spray drying. The product was white powder and dry. Meanwhile, the recovery emulsion had no surface oil and no particles linking to wall. The embedding of the product was up to 90.84%. These indicated that the embedding is better. The properties of the products were determined and the result showed that the sensory evaluation about the products was good. Scanning electron microscopy analysis on microencapsulation powdered oil showed that the particles were spherical with smooth surface and no wall-breaking, cracks and leakage, indicating embedding was better.