Research On The Quality And Processing Technique Of The Fresh Green Tea Juice

Establishing a set of processing technique of the fresh green tea juice, researching the organoleptic testing and chemical quality of the fresh green tea juice; discussing the suitable parameter and the effect of applying enzyme(pectinase tannase papain) to the fresh green tea juice. Analysising the effect of applying UHT to the fresh green tea juice on the VFC. Result showed as follow:1. Compared the quality of fresh green tea juices from three different breeds : Longjing 43, Fuding white tea and Jiukeng . And Longjing 43 is more suitable for processing the fresh green tea juice.2. The technical flow is: plucking the fresh green tea with one bud and three leaves, tedding six hours, fixing the enzyme by steam until the stem cannot be broken off. Then press ing the fixed leaves, centrifuging the rough juice with 8000rpm 15@ 15min. Applying the tannase/pectinase/papain compound enzyme to the centrifuged juice under 45@ bathing for 60 minutes. Finally, sterilizing the juice with UHT under 135@ for 5 seconds. A fresh green tea juice with excellent quality is made.3. The fresh green tea juice with different extracting techniques have big difference in quality. Comparing the juice extracted by pressing drawing extraction microwave extraction separately, finding that the juice extracted by pressing has the higher concentration, and presents the original character of the fresh green tea leaves. Drawing extraction could increase the utilizing efficiency of the tea leaves, and the quality of the juice accord with the fresh juice's character, but the disadvantage is the concentration of the juice is much lower than the juice extracted by pressing. Microwave extracting method could shorten time save energy and increase the utilizing rate, but the high temperature and microwave extraction have negative effect on the quality of the juice. An advisable way is combining the pressing method withthe drawing extraction, it could increase the concentration and the utilizing ratio of the tea leaves.4. Analysising the monomer of the catechins in the juice. The result showed as bellow: the ratio of the EGC in total catechins is far higher than the normal in the made tea infusion. And the amount of the non-estered catechins is much higher than the estered catechins in the juice by pressing. But in the juice by drawing extraction or microwave is on the contrary.5. The application of tannase pectinase and papain to the juice could prevent the tea cream improve the quality of the juice and stabilize the juice. In this three kind of enzymes, tannase is the best for preventing the tea cream. Papain could hydrolyze the soluble protein and release the free amino acids in the juice, so it could improve the fragrance and the taste. The effect of application of pectinase is inferior for preventing the tea cream, though it could hydrolyze the pectic in the juice. The compound enzyme treatment is better than the single enzyme treatment.6. The aroma characteristic of the fresh green tea juice is constituted by the alcohols, phenols aldehyde and ester aromas which represent the flower and fruit. The influence on the VFC of the juice by UHT is : the alcohols reducing, the ketone producing and increasing, the ester aroma increasing in large amount. Because the large increase of Methyl jasmonate and Acetophenone , the fragrance of flower and sweet is more obvious.7. The quality character of the fresh green tea juice by making use of the technique craft confirmed in this research is: the amount of the free amino acids and soluble protein, etc., are high, the ratio of phenols/amino acid and ester catechins/non- ester catechins are low. The taste is fresh heavy and brisk, the aroma is fresh and flowery.