Optimization And Functional Assessment Of Oligosaccharides Compound Prepared By Sweet Potato Residue

China is known to be the largest sweet potato production country in the world. Starch and starchyfood production is the primary goods of sweet potato processing in China. Sweet potato residueresulting as a poorly utilized, high-volume co-processing product from industrial sweet potato starchmanufacturing is made up of the cell walls of sweet potato tuber mainly composed of cellulose, pectinand in addition residual starch. In this thesis, the main focus was on the optimum conditions of sweetpotato residue degraded into oligosaccharides compound by using the pretreated sweet potato residueand the investigation of glyceollins accumulation in soybean seeds elicited by the oligosaccharides.The sweet potato residue was treated with sodium hydroxide solution and high shear emulsification,physical and structural difference between sweet potato residue and sweet potato dietary fiber wasobserved.16.17%sweet potato dietary fiber was gathered after pretreatment. Moreover in the sweetpotato dietary fiber content measurement experiment, the content of starch was5.71%; the content ofcellulose was44.97%; and the content of pectin was5.85%.Sweet potato dietary fiber was hydrolyzed by β-glucanase to optimize cello-oligosaccharidespreparation. The optimization of cello-oligosaccharides preparation was done by the addition of6.9×103U·g-1β-glucanase according to the weight of sweet potato dietary fiber, treatment was carried out in7h,pH=3.5, temperature was at40℃, and substrate concentration1%, the product yield was100.6mg·g-1of sweet potato dietary fiber, and the conversion rate was22.37%.Sweet potato dietary fiber was hydrolyzed by endo-polygalacturonse to optimize pecticoligosaccharides（POS）preparation. The optimization of POS preparation was done by adding1.42×104U of polygalacturonse by the weight of sweet potato dietary fiber, the treatment was done in4h at aregulated pH of2.5, and temperature was at40℃, the yield of digalacturonic acid and trigalacturonicacid was17.43mg·g-1, the conversion rate of digalacturonic acid and trigalacturonic acid was29.9%.From the results described previously, the optimum conditions for producing oligosaccharidescompound were as follows: temperature40℃, pH=2.5, concentration of sweet potato dietary fiber1%,the additive amount of β-glucanase6.9×103U·g-1and polygalacturonse1.42×104U·g-1sweet potatodietary fiber and the reaction time7h. Therefore, the yield of cellobiose was138.42mg·g-1, theconversion rate of cellobiose was33.57%; the yield of digalacturonic acid and trigalacturonic acid was25.95mg·g-1of sweet potato dietary fiber, the conversion rate of digalacturonic acid and trigalacturonicacid was44.53%.Oligosaccharides compound were used for the induction of glyceollins in soybean seeds.Comparing the results of previous experiment conducted in our lab, conditions for glyceollin elicitationare as follows: concentration of oligosaccharides compound1%; presoaked in the sterile water for5h,stored at a controlled temperature of25℃and humidity was50%in the dark for4d. The yield ofglyceollins elicited by oligosaccharides compound was1.21mg·g-1dry weight. The yield of glyceollinselicited by pectic oligosaccharides under the same condition was0.46mg·g-1dry weight soybeans respectively. Finally, the optimal conditions for elicitation were as follows: concentration ofoligosaccharides compound60g·L-1, stored at a controlled temperature of25℃and humidity of60%in the dark for4d, maximum yield of glyceollins elicited by oligosaccharides compound during thisstudy was2.11mg·g-1dry weight.