Extraction By Microbial And Study On Physico-chemical Properties Of Oatβ-glucan

Dietary fiber is a kind of natural disease-resistance carbohydrates with health care function, it is listed as the seventh largest nutrients because of the intake of which impact on human health directly. Oat bran is rich in dietary fiber, and the content is up to30%. Soluble dietary fiber of which is approximately30%, and β-glucan is the main functional components. β-glucan is able to decrease blood sugar and cholesterol, prevent constipation and reduce the incidence of colorectal cancer, promote the breeding of beneficial intestinal bacteria, and also reduce cardiovascular disease, prevent diabetes and other physiological functions. Aspergillus niger, which contains a variety of enzymes with high activity, such as amylase, protease, pectinase, cellulase and glucose oxidase, et al, utilizes nutrients of oats such as starch, cellulose as substrate for fermentation so that the β-glucan increases in purity. In this paper, we study on extraction of P-glucan through Aspergillus niger fermentation methods preliminarily.First of all, we determine the growth curve of Aspergillus niger in Czapek medium. By the method of dry-weight of cell, we obtain the logarithmic time of Aspergillus niger from24h. Then the four conditions for fermentation were explored in terms of fermentation period, age of seed, seed-liquid volume, fermentation temperature, which was based on the growth curve of Aspergillus niger. By the single factor experiments, the purity of oat β-glucan reach the highest when the age of the seed liquid of Aspergillus niger is10h, the temperature of fermentation is30℃, the fermentation period is10h, the Aspergillus niger seed-liquid volume is15mL.Eventually, by orthogonal experimention we determines conditions of fermentation technology parameters for:raw materials of oats bran is20g, the fermentation time is8h, the age of the seed of Aspergillus niger is10h, the temperature of fermentation is30℃, the Aspergillus niger seed-liquid volume is15mL. After these processes, we obtain the extraction rate of β-glucan is6.28%, purity is52.53%.Determine the other ingredients of the oat β-glucan by methods of constant-temperature drying, ashing, kjeldahl, soxhlet extraction. We obtain the content of moisture is9.02%, ash is0.66%, protein is13.15%, fat is0.82.After the determination of chromatography of sepharose CL-4B, the molecular weight of β-glucan is2.8×106. The effect of temperature on viscosity of P-glucan is significant. The viscosity is decreasing as the temperature of solution is elevating. There is a little of effect on viscosity when pH value is changing. The solubility of P-glucan is good and stable.β-glucan is good on solubility and stability.