Studies On The Extraction, Physiological Functions And Physicochemical Properties Of Water-Soluble Dietary Fiber From Soybean Hull

Few works had been done on the extraction of SDF from soybean hull.Thus the possibility of the extraction conditions of SDF form soybeanhulls by chemical,ultrasonic methods were,for the first time,explored in this dissertation.Also,the effects of some variables on the extraction by three methods were comparatively examined and the combined extraction methods were also studied.Additionally,the structure and physicochemical properties of SDF from soy hulls were analyzed.The soybean hull contains that 65.15%of insoluble fiber,8.16%of soluble dietary fiber, 6.66%of water,and little fat and proteins.It has been shown from the study on the extraction of SDF from soy hulls by chemical method that sodium hexametaphosphate solution was the best extraction agent and the extraction rate of SDF was influenced by many variables.The optimal extraction agent concentration,pH valure,solid-liquid ratio,reaction temperature and reaction time were 2%, 6.5,1:30,60℃and 2 h,respectively,under which the extraction rate of SDF from soybean hull was 25.54%Based on the single-factors experiments on the extraction of high temperature pretreated soyhulls,the ultrasonic method was adopted.The optimum ultrasonic power,ultrasonic extraction time and ultrasonic extraction temperature were 491.5 W,26.5 min and 62.6℃, respectively,under which the highest yield of soluble dietary fiber of soybean hull was 35.2218%,and the pure rate of SDF reached 81%.The soluble dietary fiber extracted from soybean hull was fed to normal mouse.The results show that soluble dietary fibers products can decline cholesterol and triglyceride level in serum,and enhance high density lipoprotein content in serum.In addition,soluble dietary fibers products can restrain the increase of weight.The fractions A1 and A2 separtated with DEAE-cellulose and purified with Sephadex G-50 were white floccule,were soluble to hot water,but no ethanol and acetone.The infrared spectrogram showed that fractions A1 and A2 have the same absorbability characteristics with like cellulose markedly.Both A1 and A2 have strong absorbability near the wave numbers of 3420 cm^-1,2932 cm^-1,1620 cm^-1,1415 cm^-1,1035 cm^-1 and 570 cm^-1.The gel permeation chromatography results showed that the molecular weight of A1 was bigger than A2. The fraction A2 constituted by mannose,rhamnose,glucose,galactose,arabonose and galacturonic acid with the molar rate of 0.60:0.74:0.29:2.29:1.43:1.00.