Study On Preparation Of Mannan From Saccharomyces Cerevisiae And Its Properties

Yeast mannan is the outermost layer of the yeast cell wall,and it is a kind of bioactive polysaccharide that gives the biological activity to cells and controls the pore size of the cell wall.It has been reported that mannan has a strong immune function.It can improve body immunity,regulation of intestinal flora balance,anti-tumor,anti-oxidation,combined with adsorption of exogenous pathogens,and with lowering blood lipids,anti-radiation and other bioactive functions.It is a very promising class of functional polysaccharide.Because of its rich biological activity and promising prospects,yeast mannan has become a hotspot of scholars home and abroad.Saccharomyces cerevisiae that is rare pathogenic reported is selected for experimental study in this paper.On this basis,we study its high temperature pretreatment,degradation,the physicochemical properties,moisturizing and oxidation resistance.Yeast cells can significantly improve the purity of manna through the process of autolysis.Adding hydrogen peroxide,anhydrous sodium acetate and sodium chloride can significantly shorten the high temperature treatment time of cell wall.To increase the yield of mannitol,the effect of adding hydrogen peroxide was the best,with 1%concentration of hydrogen peroxide,1 h of high temperature treatment time,and82.39 mg/100g of mannose production.After the high temperature leaching,the yeast cell wall was mechanically stirred and the yield of mannose was increased obviously.The higher temperature treatment is,the lower the molecular weight of the prepared mannose is.In 121?high temperature treatment of mannan heavy molecular weight was about 12.02 x 104,and in the majority with macromolecular(>10000),72.55%.The best alcohol sinking process conditions of Mannan as follows:ethanol concentration,influent concentration 10%,90%alcohol sink time 5 h,alcohol sink temperature 15?.The yield of mannose was 88.9%.The absorbance value of 1%mannose solution at the wavelength of 600nm was in a good linear relationship with its weight,which can be used to predict the weight of mannose polysaccharide.The ultrasonic treatment had the degradation effect on the macromolecular mannose polysaccharide,but microwave processing was ineffective.and the addition of H2O2 had a good degradation effect on macromolecular mannose.H2O2 method optimal conditions for degradation of macromolecular mannan as follows:25%H2O2,temperature 100°C,135 minutes treatment time.Under the conditions,the molecular weight of manna was decreased from 12.40 x 104 Da to1.10 x 104 Da.The molecular weight of the manna polysaccharides prepared by this method was still not up to the level of oligosaccharide,and the degradation process was still to be further studied.The large molecular weight YM-30 was insoluble or slightly soluble in water,while the medium molecular weight YM-50 and the small molecular weight YM-90 were easily soluble in water.The smaller the molecular weight of mannose was,the greater its solubility was.The solution of the macromolecular YM-30 solution was alkaline,while the mi-50 solution was basically neutral,while the small molecule YM-90 was more acidic.The concentration of manna had little effect on the p H value.The viscosity of the water-solution was very low,similar to the viscosity of water,and the sugar concentration and temperature had no effect on its viscosity.The infrared spectrum analysis showed that the sugar chains of the three kinds of mannose were all of the structure.In low relative humidity(RH43%),the hygroscopicity of small molecular weight YM-90 was the strongest.In the high humidity(RH81%)environment,the hygroscopicity of the high molecular weight YM-30 was the best.In the RH43%environment,YM-30 with higher molecular weight was the best moisturizer,with a moisturizing rate of 98.4%,slightly higher than that of hyaluronic acid.The yeast mannose had excellent moisturizing properties.The three kinds of mannose had great differences in antioxidant capacity of different types of free radicals.The anti-oxidative ability of Fe³⁺and superoxide ion free radicals was the best.The most antioxidant of synthetic free radical DPPH was YM-30.The strongest antioxidant for hydroxyl radicals was the YM-50.