Study On Properties And Enzymatic Hydrolysis Method Of Konjac Powder

Amorphophallus konjac is the only crop that can supply large quantities of konjac glucomannan(KGM).KGM is an important raw material for food industry,pharmaceutical industry,chemical industry,oil drilling,construction industry and agriculture.Due to its high molecular weight,high viscosity of aqueous solution,unstable performance and other characteristics,KGM is greatly limited in the food and drug industry.Therefore,the food and drug industry usually decomposes KGM into konjac glucomannan oligosaccharide by means of enzymatic hydrolysis,chemical method,physical method and so on before using it.Among them,enzymatic hydrolysis has become the mainstream method due to its advantages of mild reaction conditions,less environmental pollution and low energy consumption.Konjac glucomannan oligosaccharide is non-toxic and harmless,stable in performance,has a variety of physiological functions such as regulating blood sugar,blood fat,protecting liver,protecting intestinal health,etc.,so it has a broad application prospect in the food and drug industry.At present,most of the research on konjac is focused on konjac powder,konjac glucomannan(KGM)and konjac oligosaccharide but the studies on enzyme-hydrolyzed konjac powder are rarely reported.In view of this,Amorphophallus konjac of Huitong country was used as the material,Preparation of konjac oligosaccharide with semi-drying enzymatic hydrolysis method.The process of enzymatic hydrolysis was studied and the process conditions for the preparation of konjac oligosaccharide by enzyme method were determined,and the expected oligosaccharides were obtained.The composition of konjac oligosaccharide was analyzed by HPLC and its properties such as solubility in water,ethanol and ethyl ether,hygroscopicity,moisturizing effect were analyzed.In addition,enzyme-hydrolyzed konjac powder was used as the material,the effect on promoting intestinal probiotics colonization and antioxidant activity of enzyme-hydrolyzed konjac powder were analyzed.The main research results are as follows:1.The optimum Swelling conditions for konjac powder were optimized by single factor method and response surface Box-Behnken design.The optimal process conditions showed the solid-liquid ratio was 1:60 g/mL,particle size was 20 mesh,the swelling time was 8 h,the swelling temperature was 37 ?.The swelling coefficient of konjac powder was 18.34%.2.The optimum process conditions for konjac oligosaccharide preparation were optimized by single factor method and response surface Box-Behnken design.The optimal process conditions were initial the solid-liquid ratio was1:1.5,the buffer pH was 6.00,the hydrolysis time was 4.0 h,the enzymolysis temperature was 55 ?,enzyme dosage was 1500 U/g.The yield of konjac oligosaccharide increased to 40.98% from 38.79%.3.Konjac oligosaccharide soluble in water,insoluble in ethanol and ethyl ether,the sample is weakly acidic,its pH value is 6.76 and specific gravity is 0.70 g/mL,and have a strong hygroscopicity.In the environment with 97% relative humidity,the highest moisture absorption rate of sample reached 64%.moisture retention is not obvious,in the silicone desiccant environment,moisture retention rate is 6%.The viscosity of the aqueous solution of the konjac oligosaccharide increased with the increase of concentrations and decreased with the increase of temperature.4.Analysis of the liquid chromatogram of the konjac oligosaccharides with semi-drying enzymatic hydrolysis method,the sample may be the mixture of 5 kinds of konjac oligosaccharides.5.The experiment showed that the enzyme-hydrolyzed konjac powder can promote the proliferation of intestinal probiotics,and the increase is positively correlated with the amount of the enzyme-hydrolyzed konjac powder added.6.Enzyme-hydrolyzed konjac powder antioxidant activity test showed that solution of enzyme-hydrolyzed konjac powder had a certain scavenging effect on hydroxyl radicals,superoxide anion and DPPH.And the scavenging effect increased with the increase of enzyme solution konjac powder concentration.The scavenging rate of enzyme-hydrolyzed konjac powder on hydroxyl radicals,superoxide anion and DPPH was 40.3%,18.3% and 48.23% respectively at concentration of 25 mg/mL.