Study On Preparation Of Greentea Beverage

The green tea beverage is one of the most popular soft drinks, which is attribuated to its special taste, flavor and functionality. Green tea contains specific functional components, such as cathchin, caffeine, ascorbic acid, etc.. This study was to improve the content of the functional components and sensory quality through the hot-water extraction and color protection process; to analysis the feasibility of enchancing the low temperature storage stability by different clarification methods and keep the tea polyphenol content as well; meanwhile, the change of volatile flavors was investigated via different sterilization.The effect of green tea extraction pramameters on the color, sensory and content of tea polyphenol, which was prepared from the hot water extraction, was discussed by single factor experiment. The results was studied by the SPSS analysis of L16(45)orthogonal experiment. The optimal extraction process was as following:40 mesh, 60℃, 20 min, water/tea ratio 100:1 and pH 6. As can be seen from the relative analysis, tea infusion quality was least significantly affecedt by time, but the water/tea ratio was the most. pH and water/tea ratio was the main factor that affecting the solid content of tea infusion, while tea polyphenol content were significantly affected by temperature and pH. Water/tea ratio was significantly negative related to solid content and tea polyphenol content.However time was significantly positive related to tea polyphenol content. The color protecting effect of Vc, NaHSO₃ and ZnCl₂ on tea infusion and pigments (theaflavin) variation during extraction was studied. Through the storage experiment, it can confirm that NaHSO₃ and ZnCl₂ were the best for protecting color, and the optimal condition was 0.03% and 0.03%, respectively. The Vc might develop the prooxidant effect during storage, which destroyed the color of the tea products, so it can not implied in the green tea drink for color protection.The esters in the tea beverage increased during the high temperature sterilization through the analysis of SPME-GC-MS. The product presented a stewy flavor, though the flavor index of were significantly highlighted. However, the ultra-high temperature sterilization would not significantly change the flavor of the tea beverage.The effect of ultrafiltration and adsorbents clarification on green tea infusion was compared. As the concentration polarization and concentrate effect, the efficiency and filter speed of membrane was decreased. The flux of ultrafiltration declined quickly while time increased. Chitosan and silica can clarify green tea infusion effectively; the optimal condition for clarification was 0.04%, pH 5.5, 20 min and 0.11%, pH 3, 20 min, respectively. The Haze-active protein content was decreased during adsorbents treatment, while tea polyphenol was maintained, so the low-temperature storage experiment was highlighted. Combined treatment decreased the Pro content largely, which was good for the storage of green tea drink. The mineral content was reduced through the adsorbent treatment, and prevented mineral to join in tea cream formation...