Study Of Soil Potassium On The Change Of Amino Acids And Aroma Components In Tea Leaves

A pot and soil culture experiment was conducted to study the effect of potassium on contents of amino acid and aroma component in tea leaves.Two different tea varieties named Longjing 43 and Shuchazao,which were widely cultivated in south China,were selected.Six treatments of different potassium concentration were set up.To determine the amino acid content in tea leaves,the pre-column derivation using Acc Q-Tag chemical reagent kit from WATERS was applied for sample preparation,and HPLC system was used for quantitative analysis.Under the treatment of different potassium concentration,14 kinds of amino acid were detected in Longjing 43 tea leaves,7of which were essential amino acids for human body.13 kinds of amino acid were detected in Shuchazao tea leaves.And theanine made up 63.892% and 65.441% of total amino acid.4 kinds of amino acid,arginine,threonine,theanine and lysine,were detected in all the treatments.Except for threonine,all the amino acid content were low,some of which were even below the quantification of amino acids.This is mainly because that the tea leaves were collected among September and October.The experimental results bear out that the amino acid content in autumn tea were low.Even the theanine is much lower than that in spring tea.This result further confirmed that the low freshness of tea was related to the low amino acid content.Aroma component were extracted from tea leaves by Simultaneous distillation and extraction(SDE)method,the components were identified by gas chromatography-mass spectrometry(GC/MS).Using Ethyl decylate as internal standard,the aroma components related to low-molecule terpenoid were quantified by internal standard method.2-Hexenal(E)?2-Hexenal?Hexanol?Benzaldehyde?Hexenyl acetate?Benzyl Alcohol?Linalool oxide(trans),Linalool oxide,Linalool?Nonanal?Phenylethyl Alcohol?Methyl Salicylate ? Geraniol ? Nerolidol were analyzed.The aroma components related to low-molecule terpenoid,Linalool oxide(trans)?Linalool oxide?Linalool?Geraniol?Nerolidol,reached maximum in Longjing 43 tea leaves with 40-60 mg/kg potassium in soils.Low potassium content(< 40 mg/kg)and high potassium content(>100 mg/kg)went against the synthesis of aroma components.However,low potassium content was beneficial to the formation of Furan linalool oxide and Geraniol in Shuchazao tea leaves,and high potassium content was beneficial to the formation of Linalool.Potassium content in soils have an effect on the formation of different aroma components in tea leaves.