Study On Extraction And Purification Of Polysaccharides From Auricularia Auricular And Glycosylation Of Isolated Soybean Protein

In this paper, we used auricularia auricular as experimental material, utilized subcritical water extraction to extract polysaccharide in auricularia auricular and optimized extraction conditions by response surface methodology (RSM), analyzied effect of trichloroacetic acid, protease, sevage, AB-8 resin on deproteinization of auricularia auricular polysaccharide to obtain best deproteinization conditions, on this basis, the conjugates of AAP-soybean protein were formed by means of Maillard reaction. Box-Behnken model was used to optimize the glycation process of soybean protein, and detected functional characteristics of AAP-soybean protein conjugates and ordinary soybean protein, provided theoretical foundation for comprehensive utilization and commercial process of auricularia auricular polysaccharide. The main results were as follows:1. On the basis of the results of single-factor experiments, a Box-Behnken design was performed to achieve the best extraction procedure, The optimal extraction conditions were determined as extraction temperature 152 ℃, extraction time 26 min, ratio of solvent to material 131:1 and extraction pressure 1.0 MPa. As the result, the yield of polysacchariesn was 24.51%; compared extraction yield of polysaccharies with different extraction methods such as subcritical water extraction, water extraction method, enzyme extraction method, microwave and ultrasonic extraction method. The results indicated yield of polysaccharies through optimal subcritical water extraction was highest, what’s more, extraction time was shortest, subcritical water extraction adapted to commercial process and application in food and drug.2. To invest deproteinization process of auricularia auricular polysaccharide, effect of trichloroacetic acid, sevage, protease, protease-sevage, isoelectric point, protease-isoelectric point and AB-8 resin on protein removal rate and polysaccharide recovery rate were analyzed, the protein removal rate were 76.85%,72.17%,72.42%,76.48%,50.71%,62.24% and 78.37%, respectively. The results suggested that AB-8 resin was best method to remove the protein from polysaccharide, and optimized the deproteinization process of polysaccharide, the optimized procedure was as follows:the sample concentration was 2.07mg/mL, adsorption time was 2.06h, solid-to-liquid ratio was 1:4.87, the protein removal rate and polysaccharide recovery rate were 81.00% and 83.13%, respectively. In addition, antioxidant activity of auricularia auricular polysaccharide was increased after deproteinization, the clearance rate of hydroxyl radical and DPPH had 1.32-fold and 1.12-fold increase and reducing power was 1.89-fold as before.3. To study the optimization of preparation procedure and functional characteristics of auricularia auricular polysaccharides (AAP) -soybean protein conjugates. Box-Behnken model was used to optimize the glycation process of soybean protein, and detected functional characteristics of AAP-soybean protein conjugates and ordinary soybean protein. The optimized preparation procedure was as follows:pH 9.21, temperature 92.88 ℃, mass ratio (sugar/protein) 4.18:1 and ratio of solid to liquid is 40:1(m:Ⅴ), the binding ratio of amino acids was 21.94%. What’s more, the mulsifying activity and emulsifying stability of AAP-soybean protein conjugates had 10.75-fold and 6.15-fold improvement in comparison with ordinary soybean protein, the solubility properties and thermal stability were also improved, the study acquired optimized preparation procedure and show that AAP-soybean protein conjugates has better functional characteristics, in favour of comprehensive industrialized application of auricularia auricular polysaccharide.