关键词: 甘薯渣, 纤维寡糖, 果胶寡糖, 复合寡糖, 酶解, 大豆抗毒素

Abstract: 【Objective】The aim of this study was to explore the optimum conditions of sweet potato residue degraded into oligosaccharides by commercialized β-glucanase and polygalacturonse and to investigate glyceollins accumulation in soybean elicited by oligosaccharides, thus providing a scientific basis for the industrial production and application of oligosaccharides.【Method】 Sweet potato residue was hydrolyzed by commercialized β-glucanase and polygalacturonse separately in single factor experiments for optimal conditions such as temperature, pH, substrate concentration, additive amount of enzyme and the reaction time of hydrolysis. Product obtained was determined by thin-layer-chromatography (TLC) and high performance liquid chromatography (HPLC). The optimal conditions for hydrolysis of sweet potato residue were obtained through analyzing the yield of cellobiose and the yield of digalacturonic acid and trigalacturonic acid. Then using the combi-enzyme hydrolyze the sweet potato residue to prepare oligosaccharides compound which could elicit glyceollins accumulation in soybean.【Result】The enzyme reaction conditions for the solubilization were optimized to be addition of 6.9×103 U β-glucanase by weight of sweet potato residue dietary fiber, 7 h treatment at pH3.5, temperature at 40℃, and substrate concentration at 1%. Under these conditions, cello-oligosaccharides were mainly cellobiose, the yield of cellobiose was 100.6 mg•g-1 sweet potato residue dietary fiber, and the conversion rate of cellobiose was 22.37%. The enzyme reaction conditions for the solubilization were optimized to be addition of 1.42×104 U polygalacturonse by weight of sweet potato residue dietary fiber, 4 h treatment at pH2.5, and temperature at 40℃. Using the optimum conditions, the yield of pectic oligosaccharides mainly with a degree of polymerization (DP) of 2 and 3, the yield of digalacturonic acid and trigalacturonic acid was 17.43 mg•g-1, the conversion rate of digalacturonic acid and trigalacturonic acid was 29.9%. The optimum conditions for producing oligosaccharides compound were as follows: temperature at 40℃, pH2.5, concentration of sweet potato residue at 1%, the additive amount of β-glucanase was 6.9×103 U•g-1 and the additive amount of polygalacturonse was 1.42×104 U•g-1, and the reaction time was 7 h. Using the optimum conditions, the yield of oligosaccharides compound mainly with a DP of 2 and 3, and the yield of cellobiose was 136.97 mg•g-1, the conversion rate of cellobiose was 33.57%, the yield of digalacturonic acid and trigalacturonic acid was 25.95 mg•g-1, the conversion rate of digalacturonic acid and trigalacturonic acid was 44.53%. Oligosaccharides compound was used to induce glyceollins synthesis in soybean seeds. The optimal conditions of elicitation were as follows: concentration of oligosaccharides compound 1%, presoaked in the sterile water for 5 h, stored at a controlled temperature of 25℃ and humidity of 50% in dark for 4 d, the yield of glyceollins elicited by oligosaccharides compound was 1.21 mg•g-1 dry weight soybeans. The yield of glyceollins elicited by cello-oligosaccharides with the same concentration of cellobiose was 0.80 mg•g-1 dry weight soybean. The yield of glyceollins elicited by pectic oligosaccharides under the same condition was 0.46 mg•g-1 dry weight soybeans.【Conclusion】 Sweet potato residue, as a cheap reaction substrate, could be used as the substrate for the production of oligosaccharides compound. The optimum conditions for the production of oligosaccharides compound were obtained, and the result showed that oligosaccharides compound has good effect on the generation and accumulation of glyceollins.

Key words: sweet potato residue , cello-oligosaccharides , pectic oligosaccharides , oligosaccharides compound , enzyme hydrolysis , glyceollins