The Preparation Of Oligosaccharides By Enzymes Hydrolyzing Soybean Hull

The paper studied the extraction and purification of proteins, pectin and oligosaccharides from soybean hull, the results were as follows:1. Soybean proteins were extracted from soybean bran by acid marination, alkali extraction and isoelectric precipitation. The optimal parameters were determined respectively in the paper, (a) acid marination: the pH of digestion was 2.0, the digestion time was 2.0h; (b) alkali extraction: the pH of alkali extraction was 8.5, the time of extraction was 50min, the temperature was 75℃, the solid-to-liquid ratio was 1:10; (c) isoelectric precipitation: the pH was 4.5, the marination time was 30min. And the rotein extraction content could reach 55.26% with the determined parameters.2. Soybean hull pectins were extracted with ethanol, the determined parameters were showed as follows: the pH was 7.0, the concentration of ethanol was 70%(W/W), the time of precipitation with ethanol, the extraction yield of soybean hull pectins could be 85.53% after centrifugation and drying.3. The optimum medium for solid cultures of xylanase from Aspergillus niger was determined, in the paper. The parameters were as follows: the ratio of soybean hull and corn cortex was 2:1, solid-to-liquid ratio was 2:3, the concentration of triammonium citrate was 4.0% (triammonium citrate to solid), magnesium sulfate was 2.33% ( triammonium citrate to solid).4. The paper used xylanase to degrade soybean hull for oligosaccharides The optimal extract content was 12.02% obtained with pH 5.0, hydrolysis temperature 45℃, hydrolysis time 6h～8h, the solid-to-liquid ratio 6%～8%.5. Anion-exchange method was used to purify oligosaccharides. The best temperature was 50℃～60℃, the pH was 3.5～4.0, the optimal time was 40min, and then the conductance of oligosaccharides and the decolorizing content of oligosaccharides could reach 1.50cs/cm and 80.56 % respectively. Anion exchange resin could be reused three time at best.