| ABSTRACT:The integration process of the domestic and international markets speeding up. the consuming region of zizania gall, a unique vegitable in China, shows a rapid-growing trend. The provision of zizania gall in the international market mainly relies on the export of the domestic products and it is consumed in Chinese restaurants chiefly. American and European consumers, however, are not accustomed to eating zizania gall, for the reason that there is no support of data on the zizania gall’s as well as its cooking products’nutritions and functinal ingredients. So choosing from the traditional and modern cooking methods, this thesis deals with zizania gall by8representative cooking methods, namely blanching, stewing, cooking under constant temperature in vacuum, stir-frying, frying, hyperbaric steaming, baking and microwave cooking. And an overall study on different cooking methods’ influence over the quality of zizania gall is put forward. The quality of zizania gall is evaluated according to that as follows:the sensory evaluation, nutrients, functional ingredients, the antioxidant capacity and the adsorption of grease and cholesterol. Thus, a nutrient and healthy cooking method is optimized, which is expected to be the theory foundation of cooking zizania gall reasonably. Simultaneously, in order to lengthen the storing time of zizania gall, adjust the market supply and expand its application, this thesis makes zizania gall into powder. What’s more, a test on aspects such as nutrient evaluation, health indexes and nutrient stability is brought forward, as well as an optimimum of the processing technique of the zizania gall powder. The major conclusions are as follows:1. A study on the8cooking methods’ influence over the nutrient quality of zizania gall. The result shows that the fluid amount and the PH of zizania gall reduce by the8different cooking methods. The content of soluble solids increases greatly no matter that zizania gall is cooked by means of frying, stir-frying, blanching or stewing. The four cooking methods, whose medium is air, keep the original color of zizania gall better. The hardness of zizania gall is kept better when it is fried, hyperbaric-steamed, baked or cooked under constant temperature in vacuum. All the8cooking methods lower the ascorbic acid, the soluble protein and the content of the reducing sugar, with the influence extent of these cooking methods being different from each other. The nutrient is reserved better when the zizania gall is hyperbaric-steamed, microwave cooked, cooked under constant temperature in vacuum or baked, while the nutrient loses the most when the zizania gall is stir-fried or fried. Integrating the indexes above, there is no giant influence on the crude fiber of zizania gall when cooked by the8cooking methods.2. A study on the8cooking methods’influence over the functional ingredients and the antioxidant capacity of the zizania gall. The resulut suggests that the8cooking methods can make the content of total flavones in the zizania gall lower, especially microwave cooking, which makes the content change from38.73mg/g to37.61mg/g. And the8cooking methods can increase the content of total Phenol in the zizania gall, especially microwave cooking, which makes the content change from7.20mg/g to8.21mg/g. After the zizania gall is cooked in each of the8cooking methods, its DPPH’s free radical clearance increases to a certain extent. By analyzing the correlation among the content of total flavones, total Phenol, ascorbic acid and antioxidant capacity when cooking the zizania gall, this thesis achieves a conclusion that the content of total Phenol and the DPPH appear a linear positive correlation, which even reaches to a very significant level (p<0.01).3.A study on the8cooking methods" influence over the zizania gall’s adsorption capacity of grease and cholesterol. The result shows that the zizania gall’s adsorption capacity of saturated fat is always larger than that of unsaturated fat, whether the zizania gall is cooked or not. And there exists a fine adsorption capacity of grease. Dealing with the zizania gall at different time has few difference in the adsorption capacity of cholestrerol. And when dealed with the Zizania latifolia Turcz by hyperbaric-steaming, microwave cooking and cooking under constant temperature in vacuum, its adsorption capacity of cholestrerol is kept to a high degree.4. A study on the three drying methods’influence over the quality of the zizania gall powder. By analyzing from the angle of the powder’s Physical feature, this thesis achieves a conclusion that the yield of the powder is listed in descending order:hot air drying, vacuum freeze drying and microwave drying, and that the angle of repose is listed in descending order:vacuum freeze drying, microwave drying and hot air drying, and that the bulk density is listed in descending order:hot air drying, microwave drying and vacuum freeze drying. By analyzing from the angle of the powder’s chromatic aberrations, this thesis gets a conclusion that the zizania gall powder after microwave drying has the most prodigious difference in color. The powder’s water absorption capacity is listed in descending order:hot air drying, vacuum freeze drying and microwave drying. The powder’s Oil absorption capacity is listed in descending order:vacuum freeze drying, hot air drying and microwave drying. By analyzing the powder’s basic chemical components, this thesis obtain a series of conclusions. The fluid content is lower than5%in all the three drying ways. The powder dried in the hot air has an obviously higher content of crude fiber than that in the other two ways, and it has a higher content of protein and a lower content of fluid. The powder dried in freezing vacuum has the highest content of reducing sugar and the lowest content of crude fiber. And the powder dried in microwave has the highest content of fluid and a lowest content of protein and reducing sugar.5. A preliminary research on the optimized process of producing the zizania gall powder. The chromatic aberrations as the index of the orthogonal test, the result shows that the optimized process is when the blanching temperature is100℃, the blanching time is10min. the temperature of hot air drying is80℃, and the time of drying is7h. The content of reducing sugar as the index of the orthogonal test, the result shows that the optimized process is when he blanching temperature is80℃, the blanching time is6min, the temperature of hot air drying is60℃, and the time of drying is9h.6. A study on the stability of the product of the zizania gall powder. The result shows that all the indexes of the zizania gall powder meet the requirement within6months, and the major nutrient components stay in the product at a most high level. |
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