Research Of The Production Technology And Bioactivitise Of Yeast Glucan

Beer yeast, nutritious, with approximately30%of β-glucan, is a polysaccharides with efficentfunctions in immonomodulation, antibiosis and anti-canter. Using beer yeast to produce β-glucancan not only decrease ervironmental pollution but also increase economical and social benefits. Inthis paper, Yeast glucan was extracted from waste beer yeast by enzyme-alkali method, separated,concentrated and purified by microfiltration and ultrafiltration, and finally dried by spray drying toget the end product. The main research results are as follows:Firstly, using beer yeast powder as material, mannan oligosaccharides wasobtained by water extracting. The optimized results of orthogonal experiment were: theratio of water and beer yeast40:1. extraction time1.5h, and extraction temperature100℃. Repeat this process twice. The result showed that the yield of mannanoligosaccharides was16.35%, and the saccharide content was53.78%.Secondly, the precipitate after extracted by water was treated by2.5mol/L NaOHto extract β-glucan. The ratio of aqueous alkali and beer yeast was30:1and10:1,extracted in water-bath for1.5hours at70℃respectively,and then centrifuged andwashed thoroughly. The non-water soluble yeast glucan was obtained in precipitatedform. The result showed the yield of non-water soluble yeast glucan was17.65%, andthe content was73.11%.Thirdly, the acetic acid was added to the centrifugal clear liquid to adjust the pH.The suitable handling condition of enzymatic hydrolysis was that, the solution wasadded with2.5g/L papain and treated for8hours at pH7.0and50-55℃. Afterenzymatic hydrolysis, the liquid was separated by micro-filtration and ultra-filtration insuccession and was concentrated. Macroreticular absorbing resin was used for thedecolorization and deprotein of water-soluble β-glucan. The result showed that theyield of water-soluble β-glucan was8.72%, and it’s content was70.02%.According to the results of single factor experiment, eight factors and four levelsof orthogonal experiment was used to optimize extraction conditions. The optimizedextraction condition was that, solid-liquid ratio1:40, extraction time with hot water1.5h; hot alkali concentration2.5mol/L, extraction time with hot alkali0.5h, hot alkalitemperature65℃; enzyme concentration2.5‰, enzymatic hydrolysis time8h,enzymatic hydrolysis temperature55℃. The purification of water-soluble β-glucan. The water-soluble β-glucan wasredissoved in water and was supplied to macroreticular absorbing resin fordecolorization and deprotein further. The concentrated solution was dried bylyophilized. The result showed that the yield of water soluble β-glucan was6.52%, andthe content was91.35%. Analysis of thin layer chromatagrathy and IR, showed that,the main monomer of the purified product, with a clear absorbing peak in889cm-1inIR spectrogram, is β-glucose. The molecular weight of β-glucan was estimated to be50-180Kda analyzed by GPC.This research established a technology of extraction and purification, a distinguishmethod and HPLC content determination method for the natural water soluble yeastβ-glucan. The technology of extraction and purification has been test and verified bythe pilot studies.Biological activity research:Inhibition zone method showed that bacterial can be significantly inhibited by thewater-soluble yeast β-glucan, but the yeast and mold can not be obviously inhibited;The inhibitory to several micro-organisms are followed by Staphylococcus aureus>Bacillus subtilis> Salmonella> E. coli.Carbon clearance test: different samples of the water-soluble yeast glucan,0.1g/Kg,0.4g/Kg,1.0g/Kg, were given to mice by intragastric administration. The testproved that the macrophages phagocytic index of1.0g/Kg group compared with thecontrol group was of significant difference (p<0.05). The thymus index and spleenindex of these three dose groups compared with the control group were all ofsignificant differences (p<0.05). Those results proved that the water-soluble yeastglucan could strengthen the cellular immunity.Hemolysin antibody generated test：different doses of water-soluble yeast glucan,0.1g/Kg0.4g/Kg1.0g/Kg, were given to mice by intragastric administration. Theresults showed that three doses of the absorbance values of mice serum compared withthe control group were all of significant differences(p<0.05), which proved thewater-soluble yeast glucan may have enhancing function on humoral immune.Heredity toxicity test, including Ames test and mouse micronucleus test andmouse sperm abnormality test, were all negative. These results indicated thatwater-soluble yeast glucan is security and nontoxic.