Studies On The Preparation And Application Of Rice Bran Fiber Grafted With β-Cyclodextrin

Rice bran is a by-product of the paddy processing which has a large yield but low utilized. In this article, rice bran fiber was prepared first then grafted withβ-cyclodextrin by the cross-linking agent glutaraldehyde. A new cellulose graftβ-cyclodextrin is prepared which can be used in food. The application of this fiber in cholesterol removal in lard and egg yolk and caffeine removal in coffee have been studied in this work.A single factor experiment was designed to obtain the optimized condition of synthesis of rice bran fiber graftβ-cyclodextrin. The optimal condition is: rice bran fiber/β-cyclodextrin(weight ratio) 1, 0.5mol/L hydrochloric acid as a reaction system, the amount of cross-link agent(glutaraldehyde) added is quarter of theβ-cyclodextrin, temperature 80℃, time 30min. Under this condition, the amount ofβ-cyclodextrin immobilized on rice bran fiber is 450~490μmol/g. The DSC and IR also used to confirm that theβ-cyclodextrin is immobilized onto the rice bran fiber.The rice bran fiber grafted withβ-cyclodextrin are used in cholesterol removal from lard. According the results from one factor experimentation, the optimized process conditions of cholesterol removal from lard are as follows: adding 40% water and 8% rice bran fiber grafted withβ-cyclodextrin, reacting for 120min at 50℃. With these conditions, the content of cholesterol in lard changed from 53.98mg/100g to 7.21mg/100g, the removal rate reached 86.6%. The removal effect is compared among rice bran fiber grafted withβ-cyclodextrin,β-cyclodextrin and rice bran fiber under the same condition. It shows that the removal effect of rice bran fiber grafted withβ-cyclodextrin is best. The reclaimed rice bran fiber grafted withβ-cyclodextrin from lard can be reused after the cholesterol released. After 5 times using, the removal rate only reduce 13.4%. This methods is not only saving the producing cost but also reducing the environmental pollution. It has a better industry application value.A process to reduce cholesterol in egg yolk using rice bran fiber grafted withβ-cyclodextrin was optimized by response surface methodology aiming to define the maximum level of cholesterol extraction at a minimum decrease of the yolk protein contend. The most important variables influencing the process were dilution level of egg yolk, ionic strength, and pH of yolk suspension, as well as the amount of rice bran fiber grafted withβ-cyclodextrin used in the extraction. The fractionary factorial 2Ⅲ4? 1 was applied in the central composite design to determine the minimum number of experiments to be conducted. The yolk suspension conditions for the optimized process were 5g of yolk, 31.25g of water, ionic strength of 0.4mol/L and pH equal to 9.2 using 5.773g of rice bran fiber grafted withβ-cyclodextrin. The egg yolk contends of cholesterol and protein decreased to 85.7% and 11.3%, respectively, while the most important contend in egg yolk- lecithin only decreased to 10.1%. According to the preparative technology of instant coffee, rice bran fiber grafted withβ-cyclodextrin was applied to one of the preparation process of instant coffee to reduce caffeine in coffee. Rice bran fiber grafted withβ-cyclodextrin was added when the extraction process. A single factor experiment was design to obtain the optimal condition of the caffeine removal process. The optimized condition is: extraction time 30min; extraction temperature 90℃; coffee/rice bran fiber graftβ-cyclodextrin(weight ratio) 1.25. The comparison of unextracted coffee and extracted coffee using the HPLC shows that the rice bran fiber graftβ-cyclodextrin has a significant effect on caffeine removal and a good specificity.