Study On Preparation,Properties And Application Of Mung Bean Oxidized Starch

Mung bean starch has the advantages of high amylose content,high crystallinity,high yield,low water absorption,and high viscosity of the hot paste.It can give the food a certain color and luster,increase the flavor of the food,and improve the crispness of the food surface.It can also clear away heat and detoxify,lower blood fat,and prevent cancer.However,due to the poor solubility of mung bean starch,the moldability is more difficult,and the price is slightly higher,which limits its application in industrial production and processing.Therefore,the preparation of a new type of oxidized starch using mung bean starch has a certain significance for the development of mung bean resources and the research of starch resources.Oxidizing agents（potassium permanganate,sodium hypochlorite,hydrogen peroxide,and ammonium persulfate）were used to oxidize pure mung bean starch to obtain a better quality mung bean oxidized starch.The carboxyl content of the oxidized starch was used as the influencing factor and optimized using response surface experiments.Studied the physical and chemical properties of each product including particle morphology,thermal characteristics,crystal structure,gelatinization characteristics,viscosity characteristics,and color.Besides,we also compared the transparency,solubility,swelling,anti-aging resistance,freeze-thaw stability,and settling property of the products.In the preparation of oxidized starch:The optimal oxidation conditions for the KMn O₄oxidation method is,the reaction temperature is 45℃,the amount of KMn O₄is 2.5%,the amount of concentrated sulfuric acid is 4.5%,the amount of Na OH is 0.5%,and the carboxyl content is 0.74%.The optimal oxidation conditions of sodium hypochlorite oxidation method:p H value is 9,the reaction temperature is 45℃,reaction time is 4 h,the amount of Na Cl O is3%,and the carboxyl content is 0.65%.The optimal oxidation conditions for the H₂O₂oxidation method:p H value is 9,the reaction temperature is 50℃,reaction time is 4 hours,the amount of H₂O₂is 40%,the amount of catalyst is 0.1%,and the carboxyl content is 0.27%.Optimal oxidation conditions for（NH₄）₂S₂O₈oxidation method:the concentration of the aqueous hydrochloric acid solution is 0.8 mol/L,the reaction temperature is 50℃,the reaction time is 4 hours,the amount of（NH₄）₂S₂O₈is 4%,and the carboxyl content is 0.094%.The optimal carboxyl content measured under the optimal single factor conditions of the four groups of experiments is very close to the predicted value of the model,which indicates that the process conditions for the preparation of mung bean oxidized starch optimized by the response surface method are feasible and effective in practice.In terms of the product’s particle morphology and functional group characteristics,scanning electron microscope observation revealed that the mung bean oxidized starch prepared by the four oxidants had certain changes in the particle morphology compared to the original mung bean starch.The appearance of the mung bean oxidized starch particles is eroded,and it is concluded that the oxidation reaction mostly occurs on the appearance of the mung bean oxidized starch particles.From the analysis of the infrared spectrum,it can be seen that the four kinds of oxidized starch have C=O extensional vibration peaks at about 1730 cm^-1.In terms of product color,rheology,and viscosity.We were testing by DSC,rapid viscometer,rheometer,texture meter,colorimeter,and other instruments,it was found that the deeper the degree of oxidation,the whiter the color of the oxidized starch,and the starch oxidized by the 4 oxidants has a lower viscosity,greater elasticity and lower gelatinization temperature than the original mung bean starch.Compared with the original mung bean starch,the oxidation of mung bean oxidized starch after 4 kinds of oxidants has greatly improved adhesion,and it is more prone to gelatinization,lower viscosity,weaker settling,anti-aging,greater solubility,lower swelling force,better freeze-thaw stability,better film-forming properties,and higher film transparency greatly which improve the performance of mung bean raw starch.Selecting 3 kinds of high-quality mung bean oxidized starch to the wheat dough with appropriate proportions can greatly optimize the dough texture,flour quality,and color.In summary,the mung bean oxidized starch prepared by 4 kinds of oxidants,the mung bean oxidized starch prepared with potassium permanganate as the oxidant is more easily oxidized,the color is whiter,the viscoelasticity is better,and the oxidation time is the shortest,the performance of the obtained mung bean oxidized starch is the best.