Extraction And Physical & Chemical Properties Of Dietary Fiber From Cornus And Hovenia Dulcis Residue

Plant dietary fiber has special physiological functions on human body. Long-term consumption of foods rich in dietary fiber has a signifinant effect to prevent diseases such as cardiovascular disease, hypertension, colon cancer and so on. Therefore, great prospects can be found on research and utilization of new sources of dietary fiber which prepared from different kinds of dietary fiber.This paper mainly studies the preparation methods and partly physical and chemical properties of dietary fiber from Cornus and Hovenia dulcis residue. The results were shown as follows:(1). Preparation of IDF from Hovenia dulcis marc by chemical methods and its bleaching with hydrogen peroxide (H2O2) were studied to utilize this resource comprehensively,. The nutritional components and functional properties of the product were also analyzed. According to the results of single factor analysis and orthogonal test, the reasonable technology of extraction was that the marc was immersed in 1.5 mol/L NaOH at 20℃for 40 min, with 8:1 ratio of liquid to material then filtered and washed to neutrality. The residue was transferred into H2SO4 solution of pH value 2.0 with 6:1 ratio of liquid to material and soaked at 60℃for 60 min, then washed to neutrality. The optimum processing conditions of decoloration were as follows: 5 % H2O2, pH value 12, 45℃, 5 h, then dried at 65℃for 5 h, milled and sieved (380μm). The yield of IDF product was 74.02 % and purity increased to 84.97 % from 62.62 %. Compared with the marc, water holding capacity, oil holding capacity, water retention capacity and swelling capacity of IDF product increased from 2.4 to 4.3 g/g, 2.3 to 3.9 mL/g, 2.6 to 4.7 g/g and 2.8 to 4.6 mL/g, respectively. Binding cholesterol capacity was determined by HPLC method, and binding rate was 90% in pH 2 and 83.5% in pH 7; Binding sodium cholate capacity was determined by colorimetry method, the adsorption capacity was 27mg/g in 2mg/mL sodium cholate and 53mg/g in 3mg/mL sodium cholate.(2). Cornus officinalis Sieb. et Zucc fruit was squeezed to get juice, the spent residue can be utilized as dietary fiber. In this study, response surface methodology was used to optimize the conditions. Insoluble dietary fiber (IDF) was prepared by alkali-insoluble fractions. Central composite design was applied to evaluate the effects of three independent variables (alkalinity, ratio of liquid to material and ambient temperature) on the aggregative indicator of IDF (the product weight, IDF content and swelling capacity). The fitting equations were formed using matlab 7.0. The binomial equation was much fitted than linear equation and cubic polynomial equation to the data of overall desirability. The binomial equation was used to produce 3-D response surface graphs, through which optimal formulation were predicted. The optimum production process conditions were alkalinity (0.4214 mol/L), ratio of liquid to material (19.643 mL/g) and ambient temperature (63.37℃) for two hours. Under these conditions, the equation predicted the aggregative indicator was 19.3370. In order to verify the data, another test was made in the similar conditions. The aggregative indicator was 19.2769 and this value was very close to the predicted one. Results of these experiments indicated that response methodology was an operable method for optimization of IDF production. Binding cholesterol capacity was determined by HPLC method, and binding rate was 75.4% in pH 2 and 65.4% in pH 7; Binding sodium cholate capacity was determined by colorimetry method, the adsorption capacity was 35mg/g in 2mg/mL sodium cholate and 88mg/g in 3mg/mL sodium cholate.(3). Soluble dietary fiber was extraction from spent residue of Cornus officinalis Sieb. et Zucc fruit by ultrasonic. The conditions were optimized by response surface methodology, and the optimized conditions were ambient temperature 70.3℃, solvent to solid ratio 30 mL/g and time 110 min under the ultrasonic wave frequency of 40 K HZ and ultrasonic power of 250 W. With the yield of Cornus SDF (CSDF), content of soluble dietary fiber (SDF) and light transmittance (%, at 620 nm) as aggregative indicator, by fitting equation predicted the best aggregative indicator was 12.7845. A total of 0.25 % (w/v) dispersion of CSDF was prepared in mineral water, after UV sterilization, it presented good light transmittance (94.9 %) and shelf life (over two months). No smell and taste good. Binding cholesterol capacity was determined by HPLC method, and binding rate was 88.8% in pH 2 and 55.9% in pH 7.