Study On Processing Characteristic, Quality And Technology Of Adzuki An(With Bean Coat)

Adzuki bean is a high protein, low fat and nutritious food. As the main product of adzuki bean, an is very popular in Asian country for its unique flavor and smooth taste. In general, bean coat is removed to improve rough taste of an with the loss of nutrient, reduction of an yield. An made by whole beans, whose functional components in bean coat are contained named as "whole cereal food" is in accordance with "whole food nutrition" trend.The effects of cooking conditions on the antioxidant properties of different adzuki bean varieties and their soup are studied. The results indicate that p H value rapidly decrease from neutral to weak acid during cooking. Adzuki bean soup decreases in brightness, and increases in chroma. Obvious difference of these quality indexes are found with similar trends for the selected varieties of Adzuki bean. Total antioxidant capacity of adzuki bean and soup decrease gradually at initial stage and then remain stable. The differences between DPPH scavenging rate and total phenol content on cooking time are very significant in both beans and soup. The correlation analysis among various indexes shows that the total phenol content of soup has a significant correlation with the color value. Polyphenols content in cooked adzuki bean has no significant correlation with its antioxidant and scavenges DPPH capactiy.Effects of processing conditions on quality of adzuki an are studied by using a central composite experimental design method. Interactions of cooking time, heating power, sugar soaking time and p H value are investigated on sensory quality, color, texture properties and total antioxidant capacity of adzuki an. The cooking process of adzuki an is optimized. The results are obtained as follows. Cooking time, heating power and sugar soaking time have negative effects on the hardness of adzuki an and bean kernels. Cooking time has more significant effects on adzuki an adhesiveness and bean kernel hardness inside than other factors. The higher the p H value of sugar results in the higher the adhesiveness of adzuki an. At low heating power, influence of cooking time on the springiness of adzuki an is stronger than at the high heating power levels. Cooking process cause the total antioxidant of adzuki an decreases significantly. Effects of various factors on sensory score of adzuki an are in sequence of cooking time, sugar soaking time, heating power and p H value. The optimal bean cooking parameters are cooking time of 50 min, heating power of 1.1 k W, sugar soaking time of 2 h and p H of 8.0.The effects of carbohydrate and its derivatives including sugar alcohol, sugar ester on the texture characteristics of adzuki an are investigated by using Texture Profile Analysis(TPA). The results show that sucrose has obvious effects on the hardness, adhesiveness and gumminess of adzuki an. With the increasing of sucrose, initial hardness and adhesiveness of adzuki an increase, while adhesiveness decreases. Maltose can significantly improve the adhesiveness of adzuki an and reduce its gumminess.The effects of sugar ester are significant on the hardness, adhesiveness, cohesiveness and gumminess except for springiness. With the increasing amount of sugar esters added, the hardness, adhesion and gumminess of adzuki an are declined.The effects of carbohydrate and its derivatives including sugar alcohol, sugar ester on the texture characteristics of adzuki an in low temperature storage are investigated. The results show that: 1) carbohydrate and its derivatives had significant effects on the hardness of adzuki an in storage and the anti-retrogradation ability of sucrose was stronger than other carbohydrate. Maltose or xylitol partially replaced by sucrose, does not change the growth rate of hardness, but can significantly reduce the initial hardness of adzuki an. The anti-retrogradation effect of sucrose monoester was greater than maltose monoester. 2) Sucrose addition significantly decrease adhesiveness of adzuki an. The adhesiveness of adzuki an increased when partially replaced sugar with maltose. The effect on adhesiveness of adzuki an was not significant when partially replaced sugar with xylitol. No significant effect of sugar ester added on adhensiveness of adzuki an in storage is found. Prepared adzuki an followed by immediately process may improve its texure properties. 3) The springiness of sweetened an decreases with sugar added. Partially sugar replaced by maltose has significant effects on springiness of adzuki an in storage, and 15% replacement amount led to the higher springiness. The springiness of adzuki an in storage decreases significantly when partially replaced sugar with xylitol. There are significant influences on the springiness of adzuki an with sucrose monoester or maltose monoester added. 0.05% sucrose monoester added has the best effect on springiness during adzuki an 7 days’ storage under 4 ℃. 4) Sugar added reduces cohesiveness of adzuki an, but results in a significant increase with the increase of substitution rate of maltose. There is no significant effect on cohesiveness of adzuki an in storage when partially replaced sugar with xylitol. 0.15% sucrose monoester or maltose monoester adding has the best effect on cohesiveness of adzuki an. 5) There are significant effects on gumminess of adzuki an in storage when partially replaced sugar with maltose. Adzuki an with sucrose added is higher in gumminess than with xylitol. There are significant effects of xylitol adding on the gumminess of adzuki an. No significant effect on the changing of gumminess is found during its storage. 0.15% sugar ester decreases gumminess of sample during 4 ℃ storage.To improve the quality of adzuki an products, the gelatinization and retrogradation properties of 8 adzuki varieties’ flour and the effects of esters are determined by using differential scanning calorimetry(DSC). The results show no great differences on swelling speed of starch granules, gelatinization energy and its distribution between different adzuki beans. Compared with adzuki bean starch, gelatinization starting temperature of adzuki flour increases and enthalpy value decreases. Amylose short-term and amylopectin long-term retrogradation causes changes of the retrogradation rate following slow-fast-slow trend. In early retrogradation, the starch rertrogradation is hindered due to the existence of protein and lipid of adzuki flour. Nucleation and the nucleus growth of adzuki bean flour are different for the studied varieties. Avrami equations can exactly describe the retrogradation process of starch-protein-lipid-water system. Nucleation has a significantly influence on retrogradation rate, which results in the diffenerce of retrogradation properties of species of adzuki bean flour appear Lipid has the function to inhibit the starch retrogradation. The gelatinization enthalpy increases significantly by adding sugar esters, and inhibit functions of sucrose monoesters are better than maltose monoester.According to the optimal results, an auto cooking bean equipment is designed, which may set cooking parameters including amount of input water, water temperature and cooking time. A higher degree of automation cooking is achieved by the control of heating rate and amount of added water from the temperature sensor and water level monitoring.