The Research On The Preparation And Properties Of Konjac Oligosaccharide

As a type of important functional food material, oligosaccharide is nutritious, healthful and curative and thus is widely used in food, health food, beverage, medicine and other fields. Also oligosaccharide can substitute sucrose as a new kind of functional sugar. Since it is a new generation of functional food in the21st century and a new product which has a wide scope and prospect of application, it has become one of hot research contents in the domestic and overseas.Konjac glucomannan is a kind of water-soluble polysaccharide and has good physical and chemical properties and physiological function. While its molecular weight is large and its properties are not stable, its application in the food industry is restricted. Degradate konjac glucomannan, and we will get konjac oligosaccharide, which has kept the physiological effects of falling blood pressure, falling hematic fat and falling blood sugar and also improved the propagation of bifidobacterium. Besides, due to its small molecular weight and its good physical and chemical properties, Konjac glucomannan can be widely used in food industry as well as play its unique role in health function.Basing on the konjac gum as raw material, we have done research on the technology and optimum to prepare konjac oligosaccharide by the method of combining ultrasonic and enzymatic; have purified and identified the konjac oligosaccharide; have further analyzed the properties of konjac oligosaccharide, and then have studied the application of konjac oligosaccharide. The main results were as follows:(1)Applying the method of combining ultrasonic and enzymatic to prepare konjac oligosaccharide, we have got all factors influencing the process of konjac oligosaccharide by the result of single factor tests and have selected the three crucial factors of enzyme concentration, ultrasonic power and ultrasonic time. Furthermore, We have got the optimum condition by the response surface test with konjac oligosaccharide yield as the index:the concentration of konjac gum was80g/L, pH was natural, temperature of55℃, enzyme concentration was0.168%, ultrasonic power is76.08W, ultrasonic time was14min. In this condition, the yield of Oligosaccharides47.14%.(2)By Comparing the ultra filtration method with yeast fermentation and removing the monosaccharide from the crude product of konjac oligosaccharide, we have got the results showing that yeast fermentation is better. The optimum condition of Yeast fermentation to remove the monosaccharide from the crude product of konjac oligosaccharide is:concentration was10%, yeast inoculum was2%, fermentation time was12h. Based on this condition, the rate of removal monosaccharide was59.87%.(3)For the decolorized treatment of konjac oligosaccharide crude product, we have compared the methods of activating carbon and macroporous resin, which shows the decolorized effect of AB-8resin is better. We have found konjac oligosaccharide consists of a small amount of monosaccharides, disaccharide, trisaccharide, tetrasaccharide and pentosaccharide with the oligosaccharide impurity and decolorized, silicagel column separated and the separated components identified by TLC.(4)Through studying the properties of mail lard reaction, we have found that in acidic conditions, the color of sugar and konjac oligosaccharide’s solution changed over time. The oligosaccharide concentration of10%was better than the concentration of5%in color effect, and sugar is weaker. While under the condition of weak base, color effect was better than in acidic conditions.(5)By means of studying the inhibitory effect on the konjac oligosaccharide to starch retrogradation by using maltodextrin of the concentration of30%, DE was10, which produce the phenomenon over save time, we have found that the more konjac oligosaccharide was added, inhibition effect is more obvious.(6)By analysis on the antioxidant activity of konjac oligosaccharide by a variety of methods, we have found that when the concentration of konjac oligosaccharide was in range from2mg/mL to12mg/mL, the clearance of hydroxyl radicals, DPPH and superoxide anion have a linear relationship. With the increase of the concentration, the clearance rate will increase. Besides, Konjac oligosaccharide on the clearance rate of hydroxyl radicals and DPPH was high, which is better than superoxide anion.(7)Konjac oligosaccharide’effect on the propagation of bifidobacterium was between glucose and FOS. With the increase of incubation time, pH is declining. Bifidobacterium was cultivated24h, konjac oligosaccharide with the concentration of0.5%was slightly less than that of1.0%and1.5%on the propagation of bifid bacterium, while the latter were nearly as effective as the propagation of bifidobacterium.(8)By analyzing the results of single factor with test and designing orthogonal tests, we have got the optimum condition of preparation chrysanthemum juice is: ratio of solid to liquid was1:180, Vc was0.01%, extraction temperature was90℃, extraction time was20min. Filter by100mesh filter cloth, and we will get the chrysanthemum juice.(9)Designing orthogonal tests by analyzing the results of single factor test, we have found that the optimum condition of preparation beverage is:the ratio of chrysanthemum juice and wolfberry juice was1:4, citric acid added0.08%, oligosaccharides added6%, FOS added2%, CMC added0.15%, sterilize at121℃for20minutes after blending. The beverage we have got is pale orange, without stratification and precipitation, has the flavor of chrysanthemum and wolfberry and is little bitter and sweet and sour moderate.