The Research On Quality Variation Of Aging Dark Tea

With the introduction and rise of Chen tea culture,the characteristics of dark tea "more and more fragrant" have received more and more attention,but there is always lacked scientific and rational consumption guidance in the market.Due to the differences in the origin of raw materials and the production process,therefore these dark teas from different place of origin has different characteristics.This study collected 86 samples,it includes five varieties of tea like Liubao tea,Fuzhuan tea,Qianliang tea,Pu'er ripe tea,and Pu'er raw tea(includes two different brands).It made analysis on organoleptic quality,content of total water extracts,quality components(including polyphenols,amino acids,soluble sugar,alkaloids and single component of catechins,alkaloids,organic acids),flavor of all samples,and explored correlations between these components with storage year by the method of partial correlation analysis.The results showed that:The overall interaction of appearance of all samples was that the teas tendered to be brown and gradually loosened,and the green taste faded and unique ripe fragrance emerged.In general,the soup of fermented dark tea and Pu-er raw teas tendered to be more red.The samples with pretty material,production and storage changed in good tendency,and the samples with serious fermertation transformed slowly.The quality components of different dark teas and Pu-er raw teas changed diversely.Based on the whole sample,the trend of analysis showed a weak linear decreasing trend on the contents of total water extracts,tea polyphenols,amino acids,EGC,DL-C,EGCG,GCG,caffeine and lactic acid(P<0.05,R>0.3).Furthermore,components of water soluble sugars,total alkaloids,EC,malic acid,glutamic acid,threonine,valine,cysteine change with dis-linear trend(P<0.05,R<0.3),there was no visible trend of these quality components but they changed diversely on the basis of their category and storage.There is great difference of flavor between teas,and different substances and contents of them changed to create unique aroma types in the aging process.The analysis on the whole sample showed the increase in alcohol,aldehyds,and ketones,which were mainly fruity,floral,and woody,and it obtained the 23 characteristic aromas substances(P<0.05,R>0)of Chen tea,including 1-hexanol,2-ethylhexanol,2,6-dimethylcyclohexanol,Cedrol,isophytol,hexanal,(E)-2-hexenal,Octanal,Nonanal,(E)-2-octenal,Decanal,benzaldehyde,(E)-2-nonenal,?-cyclocitral,2,3-octanedione,6-methyl-5-hepten-2-one,geranyl acetone,?-ionone,hexahydrofarnesyl acetone,Farnesylacetone,(2,6,6-Trimethyl-2-hydroxycyclo hexylidene)acetic acid lactone,?-ionone oxide,Hexadecanoic acid.It also obtained 1 characteristic aroma substance(P<0.05,R<0)of fresh tea is pyrrole,and the charact-eristic aroma substances of stored green tea is(2Z)-2-penten-1-ol.The study is aim to explored the transformation tendency of these components during the ageing process of different dark teas in different years,and provide references for further scientific evaluation and the aging mechanism,...