Impact Of Three Different Processing Techniques On Tieguanyin Tea Quality And Pesticide Residues

Tea varieties and processing technique are two main factors to influence the quality of Tieguanyin black tea, with the former directly decide the quality of tea and the latter is the key for the production of high-quality tea. Black tea was made with the fresh tea leaves after withering, rolling, fermentation and drying, and the chemical reaction of polyphenols enzymatic oxidation as the center occurred during the process, resulting in tea polyphenols reduced by more than 90%and the production of some new composition,such as the aflavins and the arubigins.The sale market of black tea is closely related to sensory evaluation and pesticide residues,In order to improve the score of sensory evaluation of Tieguanyin black tea, three common processing techniques for black tea used in Fujian province, Souchong black tea, Congou black tea and Floral black tea processing techniques, were used to process Tieguanyin black tea. The relationship between the different processing techniques and the indexes of sensory evaluation,such as appearance, aroma, tea soup color and taste etc., were also investigated. In addition, pesticide residues largely affects the quality of tea were also used to detected their pesticide residues of Tieguanyin black tea and to analyse under different processing conditions.Sensory evaluation showed that the quality of Tieguanyin black tea made with Floral black tea processing technique was the best, followed by Souchong and Congou black tea processing technique. Tieguanyin black tea made with Floral black tea processing technique had certain advantages in two indexes of sensory evaluation, tea shape and left leaves, while Souchong tea processing technique had great advantages in three indexes of sensory evaluation, aroma, taste and soup color.Tea extract assay indicated that Souchong black tea processing technique is the most suitable to retain Tie Guanyin black tea extract, while the other two processing technologies reduce its extract in a great extent, which may affect the tea quality. In terms of microelements, Souchong and Floral black tea processing techniques are suitable for Tie Guanyin black tea in order that the human body can absorb more beneficial elements and less harmful elements. As for pesticide residues assay, bifenthrin and deltamethrin were detected, while the rest of 11 kinds were below the detection limit. It showed that pesticide residues in Tieguanyin black tea made with Souchong black tea processing technique was significantly lower than that with Floral/Congou black tea processing technique. It indicated that Souchong black tea processing technique was the best way to reduce pesticide residues in tea.According to sensory evaluation and physicochemical assay, Tieguanyin black tea made with Souchong and Floral black tea processing technique are better than that with Congou black tea processing techniques. Compared with Congou black tea processing technique, Souchong and Floral black tea processing techniques are more conductive to the formation of the quality of Tieguanyin black tea. Further studies on the comparative analysis of the differences between Souchong and Floral black tea processing techniques can provide a theoretical basis for the optimization of Tie Guanyin black tea processing techniques in the future.