The Processing Technology And Quality Characteristics Of White Tea In Shandong

White tea,which is one of the top six traditional teas in China,is popular in current society.In order to meet the consumption increase of white tea,Enrich Shandong tea category and improve the economic benefits of the tea industry,“Fudingdabai ” growing in Taian was used as material as well as “Fudingdabai ” growing in Fuding as a control,to explore the effects of different climatic conditions on raw material,withering process and tea quality of white tea;On this basis,a variety of withering methods and drying treatments were designed to study which the white tea processing technology more suitable for the climatic conditions of Taian tea area.In addition,high-throughput targeted metabolic profiles of HILIC LC-MS/MS were used to analyze the relative content of targeted metabolites in tea with different withering time,and the changes of metabolites in the withering process of white tea were explored.The results showed that:1.Compared with Fuding,the fresh leaves of the first round are slender and have fewer velvets,and the content of caffeine and soluble sugar is lower,but the content of tea polyphenols and soluble protein is higher;The climatic conditions in early spring when processed white tea in Taian,the average temperature is higher,and the average humidity and average light intensity are lower;The weight loss rate of the withering leaves in the room and by Compound withering increased rapidly,and the moderate time of withering only took 17 h,which was significantly shorter than that of Fuding(52 h);The content of soluble protein and soluble sugar in tea product was consistent with fresh leaves,and the difference of other main quality biochemical components was not significant.The tea product has a low score at sensory quality profile and the bottom of the leaves,while the taste and aroma are slightly fresher.2.The white tea processing technology suitable for Taian is that the compound thick withered for 40h~50h,the optimum drying temperature is 70°C.The finished tea processed by this process has the characteristics of white tea with good aroma and taste,and contains high soluble protein(4.21%)and free amino acid content(4.54%).3.The metabolic profiles of fresh leaves(F),two indoor withered samples for 29 h(W)and 53 h(P)respectively were investigated.Totally 111 metabolites were detected in the QC sample,including 47 amino acids and their derivatives,29 nucleic acid metabolites,12 vitamins and coenzymes,17 sugar metabolites and 6 glycerophospholipid metabolites.Compared with the fresh leaves(F),39 and 41 metabolites were significantly increased in withered samples W and P,with 35 overlapped metabolites.On the other hand,9 and 11 metabolites were dramatically reduced,with 8 overlapped metabolites.The metabolite changes suggested that the cell membranes were damaged,DNA and RNA were degraded,amino acids derivatives were significantly increased and glucose metabolism was abnormal.Furthermore,according to the variations of metabolite contents and compositions,the marker metabolites of the withered leaves were identified which could reflect the physiological states of cell membrane,nucleic acid and glucose metabolism.Eventually,based on the characteristic changes in amino acids and nucleotides,the necessities of characterizing the flavor properties of amino acids and their derivatives as well as exploring the possibility of using metabolic profiling as white tea withering standards were proposed.