Optimization Of Extraction Technology Of Pullulan Polysaccharides And Its Application Analysis

Aureobasidium pullulans(CGMCC.7055)was used as starting strain in this article.The pullulan polysaccharides fermented liquid were obtained from the fermentation culture which are used to downstream extraction optimization experiment.The article’s purpose is abandoning traditional flocculation aseptic and ethanol precipitation,the goal is industrialized production.Downstream extraction process including sterilization,removing the protein,decolorizing,concentrated by ultra filtration and drying.The moisture absorption and retention rate,viscosity stability of the extracted pullulan polysaccharides were investigated.The influence of different blend ratios on the properties of the pul-chitosan blend edible films has been investigated.Here are main conclusions of this article:First of all,remove bacteria from fermented liquid.In this article,we selected plate and frame filter to remove bacteria.Determined by single factor and orthogonal experiments,the best conditions for the filter cloth aperture of 1200 mesh,diatomite addition amount of 1.4%(w/v),the concentration of pullulan polysaccharides solution is 40 g/L.In this condition,the bacteria removal rate of 99.54%,the coarse polysaccharide yield of 93.92%.Deco to ring process was dealt with activated carbon and H2O2 respectively,depending on single factor and optimization experiments.The decolorization rate,coarse polysaccharide yield and molecular weight of pullulan were used as indexes,then we choose activated carbon under the condition of type of E,addition of 1.1%(w/v),pH of 6.0,heating time of 40 min,heating temperature of 42℃.At this time the decoloring rate was 91.69%and the coarse polysaccharide yield was 79.73%.Compared the pullulan polysaccharides obtained from the laboratory and commercial samples by infrared spectroscopy,nuclear magnetic resonance spectroscopy,ultraviolet wavelength scanning and congo red experimental measurement.We had a conclusion:they were the same kind of material in the structure,namely pullulan polysaccharides.Under atmospheric condition of RH 81%,the moisture-absorption(27.9%)and moisture-retention(89%)of pullulan polysaccharides were similar to hyaluronic acid(29%;94%).The optimal concentration for moisture-retention was 1 mg/mL(42.7 mPa-s).The viscosity had good stability to factors of temperature,pH and ion concentrationPullulan and chitosan was blended with different(1:3,2:2,3:1)ratios.Significant improvements in the mechanical and oxygen barriers properties of pullulan films ha ve been observed especially when the pullulan and chitosan blend ratio was 3:1.The characteristics of the pul-chitosan blend film(3:1)were tested:film thickness 55.4 μm,tensile strength 59.24 MPa,elongation at break 2.47%,water vapor permeability 0.415 g·mm/(m2·h·kPa),water solubility 67%,oxygen barrier 8.92 g/100g.FTIR showed the existence of strong hydrogen bonding between pullulan and chitosan.The best compatibility has been proved when the pul:chitosan blend ratio was 3:1.