New Green Tea Beverage Extraction Method And Ceramic Membrane Filtration Study

The effects of microwave and ultrasound extracting methods on the main components of tea infusion were studied. The results showed that both methods had a better effect on the extraction of the main components of tea. The contents of tea polyphenols, amino acid and caffeine reached or exceeded those of normal extracting method. They had a retaining effect on the extraction of protein and pectin. The infusion color of tea liquor extracted by microwave method was better..Main kinds of catechins in tea liquors extracted by different extract methods were analyzed by HPLC. The results showed that total amount of catechins in ultrasound extracting infusion were higher than that of other extracting methods, especially the content of EGCG. D,L-C was detected in microwave extracting infusion and ultrasound extracting infusion. EGCG would probably be isomerized to from GCG under high temperatureAnti-sediment effect of infusion by different extracting methods was studied at 4癈. The results showed that ultrasound-extracting infusion had a better anti-sediment effect, which had not produced sediment for three months. Microwave-extracting infusion, which was found sediments after one month, was slightly better than the normal extracting infusion.Aroma in tea infusions with different extracting methods was analyzed by GC. The results indicated that microwave and ultrasound were benefit to the extract of essential oil. Total amount and kinds of essential oil in microwave-extracting and ultrasound-extracting infusion were more than those in normal extracting method. FI in microwave-extracting and ultrasound-extracting infusions increased obviously compared with that of normal extracting method. Glycosidical aroma precursors in different extracting tea infusions were studied. The results showed the extract of glycosidical aroma precursor was promoted by using microwave and ultrasound.Studies on the filtration effect of green tea infusion showed that the membrane permeate flux decreased greatly at the early stage, and then varied gently. The analysis on the retaining rate of the main compounds by 0.2 m pore size ceramic membrane showed that the retaining rate of tea polyphenols, amino acid, caffeine was relatively low, while the retaining effect on the protein was apparent.