| In this study, Ginkgo biloba shell was used as the test material. The dietary fiber was prepared by using a-amylase and protease to hydrolyze starch and protein. Then, use xylanase and cellulase to modify the G. biloba shell dietary fiber, with the water holding capacity as the indicator, use orthogonal to optimize the modification conditions, and the optimum process parameters were obtained. After that, the paper compared the physicochemical properties of the G. biloba shell dietary fiber before and after the modification, and explored the feasibility of applying it to the production process of cookies. The main conclusions are as follows:(1)The total dietary fiber content of G. biloba shell was 86.24%, and the mainly non-fiber composition was fat, starch and protein, so using the alpha amylase and protease to remove starch, protein, was the preparation of G. biloba shell dietary fiber.(2)On the basis of single factor experiment,use xylanase, and cellulase to modify G. biloba shell dietary fiber, then design the orthogonal experiment and get the optimal modification process combination:xylanase addition amount was 24U·g-1, cellulase addition amount was 30 U·g-1, enzymolysis temperature was 50℃, pH was 5.0, mensurating the water-holding capacity of G.biloba shell dietary fiber is 4.72g·g-1, and the water holding capacity increased by 33.34%,compared with dietary fiber before the modification.(3)Compare the physicochemical properties of modified G. biloba shell dietary fiber before and after. We could see that before and after modification, the water holding capacity, oil holding capacity and swelling power were increased by 33.34%,10.59%,26.09%, respectively, and the cation exchange capacity of the dietary fiber was 1.14 times the unmodified; simulating human gastric juice, from the dynamic adsorption of NO2- on G. biloba shell dietary fiber, we found dietary fiber on NO2- adsorption equilibrium is reached, in the reaction system of dietary fiber before and after modification, the concentration of NO2- were 4.92 μmol·L-1, 4.35μmol·L-1, G. biloba shell dietary fiber can make NO2- concentration in the stomach dropp to a safe level of was (NO2- concentration less than 5 μmol·L-1), and adsorption capacity of the modified dietary fiber is better; simulating human intestines and stomach, from the adsorption of cholesterol to G. biloba shell dietary fiber, we found when pH was 2, cholesterol absorption capacity was weaker than the capacity when pH was 7,in the same pH environment, the cholesterol’ adsorption capacity of modified dietary fiber was better than untreated; from the adsorption of sodium cholate by G.biloba shell dietary fiber, we found, with time increasing, the adsorption amount of G. biloba shell dietary fiber increased gradually. When the reaction time is nearly about 180 min, the absorption of sodium cholate reached the saturated state. At this point, the dietary fiber before and after modification made the solution concentration of sodium cholate reduce to 1.79g·L-1, 1.85g·L-1, adsorption amount of sodium cholate was15mg·g-1 and 21mg·g-1, respectively, indicating that the adsorption of of sodium cholate by modified dietary fiber was faster with better adsorption capacity.(4)Apply 0% to 3%,6%,9%,12% and 15%, six kinds of G. biloba shell dietary fiber adding amount to the cookies formula. Apparently, with the increase of G. biloba shell dietary fiber adding amount, spread factor first increased and then decreased; the brightness decreased, and yellow tone falled, relatively dark; the hardness and fracturability increased, with the increase of storage time, cookies with the same adding amount decreased in hardness, chewiness and resilience increased after the first drop; 0%,3%,6%,9% of adding amount reached a good level in sensory evaluation, on which people can accept the cookies better, Integrated many factors,9% of dietary fiber is more suitable. |
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