Effects Of Extrusion And Other Heat Treatments On Physicochemical Properties Of Adzuki Bean Powder

Adzuki bean is a kind of bean food with rich nutritional value,which can be used as the ingredient of a variety of food.With the improvement of living standard,the market of adzuki bean powder is more and more broad,and the premise of production and processing of adzuki powder is to carry out curing heat treatment.The effects of extrusion conditions(moisture content and extrusion temperature)on the physicochemical properties of adzuki bean powder were studied with adzuki bean as raw material,and the optimum extrusion conditions were determined.The effects of heat treatment on physicochemical properties of adzuki bean powder were studied after hot air drying,frying and microwave treatment,and compared with extrusion treatment.To study the influence of different heat treatment methods on the quality characteristics of adzuki bean powder,in order to provide theoretical basis for the development of adzuki bean powder and instant powder.The main conclusions are as follows:The physical and chemical properties of adzuki bean powder under extrusion conditions were studied.The results showed that adzuki bean powder would aggregate and agglomerate during extrusion,and the degree of agglomeration would increase significantly with the increase of water content and extrusion temperature.According to the color analysis,the color of adzuki bean powder changed obviously after extrusion(P<0.05).Infrared spectrum analysis showed that no new functional groups were formed after extrusion,but the order of the double helix structure decreased.According to the analysis of hydration characteristics,the water absorption index(WAI),water solubility index(WSI)and expansion potential(SP)of extruded adzuki bean powder were significantly higher than those of unextruded adzuki bean powder,and WAI and SP increased with the increase of water content and temperature.When the water content was 22%,WAI and SP are 2.70 g/g and 3.30 g/g,respectively.When the extrusion temperature is 220?,WAI and SP are 3.18 g/g and 3.92 g/g,respectively,while WSI change is opposite.In addition,gelatinization characteristic values,gel strength and whole texture characteristic values of adzuki powder decreased significantly with the increase of moisture content and extrusion temperature(P<0.05).According to the above indexes,the extrusion conditions of adzuki bean powder were determined as 18% moisture content and 180? temperature.The physical and chemical properties of adzuki bean powder were studied by other heat treatment methods.After heat treatment,L* value(brightness)decreased while a* value(redness)and b* value(yellowness)increased.a* value(2.53)and L* value(69.03)of adzuki bean powder were the highest after extrusion treatment,and b* value(9.61)of adzuki bean powder was the highest after microwave treatment.The results of hydration characteristics showed that WAI,WSI and SP of adzuki bean powder increased significantly after heat treatment(P<0.05),while WSI and SP of adzuki bean powder increased 1.87 times and 1.39 times after extrusion treatment,respectively.The gelatinization characteristic values of adzuki bean powder after heat treatment were significantly decreased(P<0.05),and the regeneration value of adzuki bean powder after microwave treatment was the lowest(625c P),indicating that microwave treatment could significantly inhibit the regeneration of adzuki bean powder.The results of texture properties showed that the gel strength and hardness of red bean powder changed significantly with different heat treatment methods(P<0.05).The gel strength and hardness of red bean powder after hot air treatment were the highest(88.49 g and 95.79 g,respectively).The results of thermodynamic characteristics showed that the thermodynamic temperatures(To,Tp and Tc)of adzuki bean powder increased after heat treatment,while the enthalpy values(?H)decreased significantly,and the ?H was the lowest(0.39 J/g)after extrusion treatment.In addition,compared with other heat treatment methods,the resistant starch content of adzuki bean powder after extrusion is relatively higher(8.17%).The results showed that the dispersing time and agglomerating rate of adzuki bean powder were different after different heat treatments.The dispersing time and agglomerating rate of adzuki bean powder were the shortest(19.45 s)and the lowest(33.55%)after microwave treatment.The results of electronic nose and electronic tongue showed that the flavor and flavor of red bean powder changed significantly after heat treatment.The flavor became richer,and the alkane compounds decreased,while the alcohol and ester compounds increased.The results of food caloric analyzer show that the content of heat components will change after heat treatment.The static rheological properties show that the red bean powder after heat treatment has pseudoplastic characteristics,and presents shear thinning phenomenon with the increase of shear rate.The results of temperature scanning showed that the storage modulus(G')and loss modulus(G ")of adzuki bean powder will increase gradually with the increase of temperature,and in the whole heating stage,the G' value of adzuki bean powder after heat treatment is greater than G" value,indicating that the sample is elastic.In addition,the sensory evaluation results showed that red bean powder after hot air drying had the highest acceptance degree(total evaluation score of 69.2).