Study On Extraction Technology Conditions Of Pullulan Polysaccharide In Fermentation Broth

Pullulan is a new microbial polysaccharide which is widely used in food industry medicine and so on. In this paper, we mainly studied the extraction process conditions of pullulan polysaccharide. It mainly included clarification, decolorization and removing protein in extraction of microbial polysaccharides.The main results obtained are as follows:Prepare the pullulan fermented liquid by Strain Y68, a high pullulan yield yeast strain. The study found that the fermentation time of 70h when the polysaccharide content in the fermented liquid was higher. At the same time, explore methods to eliminate the bacteria in the fermented liquid, using microfiltration membrane filtration method and flocculation method by ferric trichloride, aluminium chloride, ferric sulfate, aluminum sulfate, ferrous sulfate and ferric chloride to remove bacteria in the fermented liquid. The results showed that microfiltration membrane filtration method was more suitable for removing the bacteria in the fermented liquid of pullulan polysaccharides, and under the pressure of 0.1 MPa, microfiltration membrane filtration could completely remove the bacteria in the fermented liquid.Using magnesium silicate, sepiolite and attapulgitet to remove of pigment and protein from the pullulan fermented liquid, this paper investigated:After the adsorption by magnesium silicate, under such conditions, 1000min adsorption time,45℃ adsorption temperature, pH value 3.2 and 1.6% magnesium silicate, the decolorization ratio was 51.59%, the deproteinization ratio was 56.25% and the polysaccharide recovery ratio was 82.25% After the adsorption by sepiolite, under such conditions,80min adsorption time,45℃ adsorption temperature, pH value 3.2 and 2.0% sepiolite, the decolorization ratio was 61.64%, the deproteinization ratio was 65.16% and the polysaccharide recovery ratio was 88.82%. After the adsorption by attapulgitet, under such conditions, 100min adsorption time,35℃ adsorption temperature, pH value 3.2 and 2.0% attapulgitet, the decolorization ratio, the deproteinization ratio and the polysaccharide recovery ratio was 73.27%,70.81%,92.98%, respectively.The results showed that attapulgitet was the most suitable one from these three kinds of adsorbents.With activated carbon, diatomite and bentonite, three kinds of common adsorbents, removing of pigment and protein from the pullulan fermented liquid. This paper investigated how the ratios of decolorization, deproteinization and polysaccharide recovery changed along with the adjustments of adsorption time, temperature, pH and dosage. The results showed that these three kinds of adsorbents all performed well in adsorbing the impurities,and diatomite was the most suitable one. Based on the single factor experiment, diatomite was then chosen for the orthogonal experiment. The results showed that the optimal processing conditions were as follows:60min adsorption time,35℃ adsorption temperature, pH value 3.2 and 1.6% diatomite. Under such conditions, the decolorization ratio was 80.17%, the deproteinization ratio was 76.28% and the polysaccharide recovery ratio was 89.82%.By comparing decolorization, deproteinization and removal of conditions, screen the best one from D3520, D4020, D4006, D101 four kinds of macroporous resins. The results showed that D4020 resin is suitable for pigment and protein removal of pullulan polysaccharide in the fermented liquid. The results showed that the optimal processing conditions were as follows: 80min adsorption time,25℃ adsorption temperature, pH value 3.2 and 1.6% diatomite. Under such conditions, the decolorization ratio was 71.69%, the deproteinization ratio was 59.98% and the polysaccharide recovery ratio was 86.25%.