Research On Processing Technology And Quality Evaluation Of Sichuan White Tea

White tea is one of the six major teas of our country, which belongs to lightly fermented tea, widely distributed in Fuding and Zhenghe of Fujian province. In recent years, due to White tea’s fresh and sweet quality characteristics and unique health functions, it is becoming more and more pouplar among consumers, showing strong market demand. However, traditional white tea "concentrated areas, limited output" and "hard to shape" has become an important factor of its development. According to these key problems, in this paper, the white tea introduced in Sichuan as the premise, put forward the concept of Sichuan white tea production to meet Sichuan consumption of white tea drinking habits, that is to choose Sichuan local multi pekoe tea varieties of fresh leaves of tea raw material, dominated by the sichuan consumer market, learn basic processing tea from Fujian, and make the appropriate shape.At first, the study of the Sichuan White tea quality changes during the processing were researched using the fresh leaves of Sichuan local tea tree species. Also, Sichuan white tea processing technology and the relationship between the quality formations were discussed. On the basis of these, the raw material resources and the key process parameters are optimized, the processing technology and parameter were determined, provideing a theoretical basis and technical guidance.for Sichuan white tea processing technology and quality evaluation. Then comparative study were taken between Sichuan white tea and tradition white tea.In adition,sensory quality, physical and chemical quality and aroma components of Sichuan white tea have carried on the analysis and evaluation. The following results are achieved:(l)Reference to traditional white tea processing technology and new craft white tea, it has axplored a set of Sichuan white tea processing technology,and providing basic datas for optimizing process parameters.(2)Fresh leaves of Fu Ding Da Bai Cha variety are as raw materials, according to the major process for Sichuan white tea processing, it has explored the influence of different process parameters on quality, to determine the best process parameters.Different withering time:Withering experiment was carried out with different withering time (12h,24h,36h,48h,60h).By combining with sensory evaluation main quality composition analysis, the proper withering time is 48 hours,when the temperature is from 20-25℃ and the humidity is 70%-75%.Different withering temperature:When the environmental humidity was (70±5)%, different temperature (18±2)℃, (23±2)℃, (28±2)℃, (33±2)℃experiment was set. The results showed that the proper withering temperature was (28±2)℃, the proportion of the main quality ingredients is appropriate.Different withering humidity:When the environmental temperature was 20-25℃, different wilting humidity (60±5)%, (70±5)%, (80±5)%experiment was set. The results showed that the proper withering humidity was (70±5)%,whose sensory quality is sweet and fresh in taste.Different pretreatment before shaping:Using different pretreatment methods (water spray humidification, steam humidification, humidifier humidification) to deal with the withering leaves, the results showed that the proper method is follow.Firstly,spray humidifying withering leaves, after the use of humidifier control environment humidity, keep it at 100%, leaves can be soft in about 30 min, at this point, the withering leaf water content reaches 35%, blade restore soft, can achieve the requirement of the shape.Different methods of shaping:Using different ways of shaping article (rolling, daniel, after the first rolling bar) for humidifying withering after processing. The results showed that the sample processing of sensory evaluation optimal. The color is gray green, flower chandelier, tang apricot yellow and bright, taste sweet alcohol and refreshing. The difference between the main quality components and controls is small. And soluble sugar and water extract is higher than controls, the concentration of tea liquor and sweetness were increased.(3)To explore the influence of different fresh leaves raw materials of Sichuan white tea quality:Using different tea varieties (Fudingdahao、Mabianlv 1、 Fudingdabai-Mengshan 9、Fuyun 4、Chuanmu 28、Fuxuan 9),different picking standard materials (bud, a bud leaf and one bud two leaves) and different picking season (spring,summer,autumn)of tea fresh leaves materials, the results showed that in addition to Fuxuan 9 varieties, the other six varieties can satisfy the requirement of Sichuan white tea quality, especially Fudingdahao and Mabianlv 1.Using Fudingdabai variety as raw material to make Sichuan white tea,the tea made of bud was the best,the difference between one leaf and one bud two leaves raw material quality is not significant. Using one bud two leaves of Fudingdabai variety as raw materia, the tea that made in spring is the best.(4)Sensory quality and biochemical components, amino acid and catechins composition content and aroma composition characteristics of Sichuan white tea and the traditional white tea were compared, the results showed that the Sichuan White tea can keep white tea’s milli incense, fresh quality characteristics, and the appearance is smaller, compared with traditional white tea, the taste is a bit thick, aroma increased on the basis of the original scent flavor; Analysis of the main flavor substance, Sichuan White tea is lower than the traditional white tea, white tea polyphenols content, soluble sugar and water extract content increased slightly; From the point of amino acid and catechins composition, sichuan white tea with traditional white tea has a total of 19 kinds of free amino acids were detected no significant differences in total amino acids, catechins content, content is slightly different between components. From the point of aroma composition and the type, Sichuan white tea aroma contained species (65) than traditional white tea (56), the main types of aroma and slightly different aroma. The content of cis-3-hexenal and cis-3-hexenol is higher than the relative Sichuan white tea, showing outstanding fragrance; the sweet substances relative content of Sichuan white tea is higher than the traditional white tea, sweet and fragrant sensory performance.