Preparation And Application Of Konjac Manno-oligosaccharides And Research On Its Antioxidation

With the improvement of people's living standards,the health of residents is damaged seriously by chronic diseases caused by dietary imbalance,such as obesity,diabetes and hypertension,for which functional food of oligosaccharides has a good health care effect.The main component of konjac tuber is glucomannan with many shortcomings,such as high molecular weight,high viscosity and unstable properties,which limit its application in food industry.Hydrolysis of manno-oligosaccharides with smaller molecular weight and low viscosity is more suitable for food industry.In this paper,the purification technology of konjac glucomannan from konjac flour was optimized,and the controlled hydrolysis process of konjac manno-oligosaccharides was studied,and the antioxidant activity of konjac manno-oligosaccharides with different hydrolysis degree was studied,and a compound juice of kiwifruit and cucumber with konjac manno-oligosaccharides was developed.The following results:(1)Method of ultrasound-assisted ethanol precipitation was used to purify konjac glucomannan.Response surface methodology and single factor experiment were used to optimize the purification technology.The optimum parameters were as follows: ethanol concentration was 82%,ultrasonic temperature was 51?,ultrasonic time was 60 min,ultrasonic power was 180 W,and the predicted value of konjac glucomannan content was 98.55% while the actual measured value under the optimum parameters was 98.18%.The model fitted very well.The purification technology without adding impurities,causing destruction to the molecular structure of glucomannan cost less and obtained products with the purity of 98% or more.(2)The hydrolysis of konjac glucomannan can be well catalyzed by Viscozyme L which made the degradation process of konjac glucomannan can be controlled.Konjac manno-oligosaccharides with different hydrolysis rates was obtained by controlling the hydrolysis time,which is the key factor affecting the enzymatic hydrolysis of konjac glucomannan.It is characterized by rapid degradation of initial 0.5h and slow degradation.In this paper,under the condictions of temperature was 55°C and the enzyme concentration was 174U/g,the konjac manno-oligosaccharides hydrolysis rates of 13.9%,22.4%,30.6%,37.9% and 48.0 % were obtained by controlling reacting time.(3)Different antioxidant activity was exhibited by konjac mannooligosaccharides with different degrees of hydrolysis.It showed stronger scavenging ability to·OH and DPPH·while weaker scavenging ability to superoxide anions,within the hydrolysis rate ranging from 13.9% to 48%.(4)A konjac manno-oligosaccharides compound fruit & vegetable juice was developed.The optimum processing parameters of konjac mannano-oligosaccharides compound fruit & vegetable juice obtained by single factor experiment and orthogonal experiment were as follows: the ratio of kiwi fruit juice to cucumber juice was 3:2,the percent of konjac manno-oligosaccharides was 6.5%,the percent of citric acid was 0.10%,and the percent of xanthan gum was 0.15%.The obtained juice with light green color,moderate sweet and sour taste,coordinated odor of kiwi and cucumber had rich nutrition and no precipitation.It can not only relieve thirst and provide essential vitamins and minerals for human body,but also contains konjac manno-oligosaccharides,which can regulate intestinal flora and be beneficial to human health.