Application Of Microwave Technology On Extraction Of Green Tea

In pace with the enhancement of social production force, tea comprehensive processing become the leading point in economic progression and offers powerful theory support for the effective combination of tea production and function food, health care production, living and industrial products ect. The development of products like instant tea, tea polyphenol, catechins represents the present technology level of tea comprehensive process. Extracting is one of the key steps of the tea comprehensive process. The gain rate and quality of production after extracting and the efficiency during extracting which can be the economic index to judge the next separator, purification and concentration's feasibility. The recent Green tea extracting tech use in industrial manufacture contains: using the de-ioned water at between 90 -95℃ as solvent, twice extracting: the first time with tea:water 1:8 and the second time is l:7,for 30 min each time. Because of the tea quality components' hot changing, polymerized and other physical and chemical characters in traditional extracting, the extracting process in opposite long time and high temperature lead to problems like a low rate, worse cool solubility and low efficiency, etc.With the development of science and technology, how to improve the gain rate, quality, processing efficiency and the time and energy —saved extracting method has become the research's hot spot. Microwave is one latest tech of energy sources. It takes the advantage of heating quickly, warning the exterior and interior of material at the same time, saving energy in process easily to control and operate, and has been widely used for heating and drying in food process .Microwave tech should get a good effect on the use of extract in tea comprehensive process by theoretical prove, although there's no report on this area.This green tea extracting experiment compares the microwave extracting system with traditional water extracting taking the use of recent industrial extract tech as the back ground, the use effect and extended foreground extract technology as goal.Take the household microwave oven's medium wave intensity (400w) as the microwaveintensity and on the premise of the same volume of filtrated liquid as traditional extract ,on the aspect of the efficiency of extract in the extract quantity of green tea quality components, polyphenol:amino acid in green tea material liquid and the time and energy used for extracting .On the premise of the microwave extract's obvious advantage in gain rate ,quality and work efficiency of the product has been proved, optimize the tech parameter of material's degrees of thickness, intensity of microwave kind of solvent ,time of extracting ,times of extracting and the ratio of tea :water ,by the analysis of the catechin's HTPLC and TCLC ,have studied on the microwave extraction effect on the green tea's catechins ,and discussed the feasibility of the new microwave extracting tech used for tea comprehensive process ,and got the following conclusions:(1) Compared to the usual extracting ,microwave extracting has high gain rate of water extracts ,polyphenol, amino acid, caffine, water soluble protein ,soluble carbohydrate ,total catechin and other quality components than traditional extracting .The ratio polyphenolramino acid increased a little by microwave extract ,but still in acceptable scope and the extracting time and energy was reduced obviously by microwave in work efficiency.(2) The ideal technology parameters for green tea microwave extracting are deal with the material to 12 holes ,adopt 400w as microwave intensity ,use the purified water at normal temperature as extract solvent and 1:15 as the ratio of tea:water ,extracted twice ,the first time is 1:8 and the second time is 1:7 and extract 4min each time.(3) The catechine HTPLC and TCLC analysis showed that , microwave extracting has effect on the catechin change ,but the difference is not significant.Consequently ,microwave technology can be used not only as a new method in green tea extracting ,but also has the advantage than traditional water extracting in the quality component of gain rate ,quality and work efficiency, but also have a advanced study on the problem about the security and the mechanism about the quality component changed in microwave extracting .