| β-Glucan has a lot of kinds of biological activities,including immune regulation,anti-tumor,lowering blood lipid,anti-oxidation,anti-radiation,regulating intestinal flora,etc.,and is widely used in breeding industry,food industry,pharmaceutical industry and cosmetics industry.Saccharomyces cerevisiae is the main source ofβ-1,3-glucan,however,most of the saccharomyces cerevisiae is discarded directly or sold cheaply as feed,which is a great waste of resources.Therefore,to extract yeastβ-glucan from Saccharomyces cerevisiae can not only improve the utilization of resources,but also decrease environment pollution,which has high economic and social benefits.Currently,many different kinds of methods have been used for yeastβ-1,3-glucan preparation,such asacid method,alkali method,and acid-alkali method,etc.However,a large amount of acid and alkali can not only degrade the yeastβ-1,3-glucan,but also lead to equipment corrosion and environment pollution.Therefore,a highly efficient,convenient,pollution-free preparation method is urgently needed for the extraction of yeast β-1,3-glucan from Saccharomyces cerevisiae.In this paper,a method of enzymatic digestion combined with high-temperature extraction to extract β-1,3-glucan from the Saccharomyces cerevisiae was established so as to avoid the use of acid and alkali in the extraction procedure,and the effect of the yeast β-1,3-glucan on the regulation of intestinal flora in mice was also studied so as to provide the basis for the application of the yeastβ-1,3-glucan.The main contents,results and conclusions are as follows.1.The preparation procedure of yeast β-1,3-glucanThe newly estalishend preparation procedure consists of two main steps.First,enzymatic digestion was used to remove the proteins of the yeast cell wall.Second,high-temperature extraction method was used to remove the mannan of the yeast cell wall.For the process of protein removal,the ability on protein removal of five kinds of proteases,alkaline protease,acid protease,neutral protease,yeast extraction enzyme and papain,were investigated,and the results showed that the ability of alkaline protease and yeast extraction enzyme on protein removal are better than others.The use of the two enzymes for protein removal was also optimized,and the results showed that the effect of combination use of these two enzymes on protein removal was better than they were used alone.Then the optimal enzymatic conditions of alkaline protease and yeast extraction enzyme were determined respectively by single factor experiment and orthogonal experiment.The optimal enzymatic condition of alkaline protease was as follows:the enzymolysis temperature was 40℃,the pH was 11,the amount of enzyme was 1%and the enzymolysis time was 4 h.The optimal enzymatic condition of yeast extraction enzyme was as follows:the enzymolysis temperature was 50℃,the pH was 9,the amount of enzyme was 0.8%,and the enzymolysis time was 4 h.The effect of high-temperature extraction on manman removal was determined.The results showed that the when the high-temperature extraction time lasted for 6 h the mannan content of the product was the minimum.2.The determinations of polysaccharides and proteins of yeast β-1,3-glucan sampleThe phenol-sulfuric acid method was used to determine the total sugar content of yeast β-1,3-glucan product,and the gas chromatography was used to determine the contents of glucan and mannose.The Kjeldahl method was used to determine the content of proteins.The results showed that total sugar content of the yeastβ-1,3-glucan sample was more than 75%,the content of glucan was more than 70%,mannose was less than 4%,and protein was less than 6%compared with the total glucan content of yeast β-1,3-glucan reference 75.6%and protein 6.4%.3.The nature of the yeast β-1,3-glucan sampleThe yeast β-1,3-glucan product was a gray powder.Infrared spectrum analysis showed that the glycosidic bond type of yeast glucan sample was β-1,3-glycosidic bond.Gas chromatography was performed to determine the monosaccharide composition,and the results showed that the yeast β-1 3-glucan sample mainly contained glucose and 2.6%mannose,but the yeast β-1,3-glucan reference only contained glucose.4.The effect of yeast β-1,3-glucan on the regulation of intestinal flora in miceThe effect of yeast β-1,3-glucan product on the regulation of intestinal flora in mice was studied using microbial culture method.The mice were orally administrated with the yeast β-1,3-glucan sample(250 mg/kg)for one month,and the results showed that the number of pathogenic E.coli decreased significantly,and the number of probiotic excrement enterococcus increased,but not significant compared with the control group.The results indicated that the yeast β-1,3-glucan has some effects onregulating intestinal flora of mice. |
