The Research On The Composition Of Yellow Tea And White Tea

In this paper, the chemical compositions of different kinds of the yellow tea and whitetea samples that type in vitamin C, tea polyphenols, caffeine, procyanidins, theaflavins andvolatile components were analyzed.High performance liquid chromatography (HPLC) method for yellow tea and white teahas carried on the quantitative analysis of vitamin C content in different samples. Under thecondition that1.0%phosphoric acid solution as mobile phase, flow rate is1.0mL/min, thecolumn temperature at30℃,and detection wavelength is238.2nm, the linear regressionequation of the method is: y=32402x+55651, the correlation coefficient r=0.9999, thestandard deviation is0.2991,andthe variation coefficient is5.637%, with higher accuracy andprecision. The experiment results show that the vitamin C content in the samples of yellow teais higher than that in the samples of white tea. HuoShan HuangYa samples have the mostvitamin in Yellow tea, which is789.05μg/g.Using high performance liquid chromatography (HPLC) method for different samples ofyellow tea and white tea to simultaneously detect the content of EGC, EGCG, ECG, caffeine.Mobile phase is Vmethanol: Vacetic acid: Vwater=25.0:2.0:73.0and detection wavelength is274.8nm. The linear regression equationof EGC is: y=2795.1x+15264, the correlationcoefficient is r=0.9997; the linear regression equation of EGCG is: y=15741x-1510, thecorrelation coefficient is r=0.9998; the linear regression equation of ECG is:y=15118x+56299, the correlation coefficient is r=0.9997;the linear regression equationof CAF is: y=33902x-55560, the correlation coefficient is r=0.9996. Accuracy and precision of thismethod are both higher.By high performance liquid chromatography with electrospray tandem massspectrometry for yellow tea and white tea, procyanidins, B1, B2, and theaflavins from differentsamples were determined respectively. Results show that in the two kinds of tea, the contentof Procyanidins B1and B2in yellow tea is higher. In yellow tea,Procyanidins B1of JunShanYinZhen (7.320mg/g)and B2(3.394mg/g) are the highest. Two kinds of tea in the highestcontent of procyanidins B1and B2are both JunShan YinZhen, which emerge that JunShanYinZhen> HuoShan HuangYa> MengDing GanLu> BaiHao YinZhen> ShouMei; Thecontent of theaflavins inWhite tea is higher than in yellow tea,and the content of theaflavins in white tea in the ShouMei of the content of theaflavins (1.034mg/g) is the highest.The contentof theaflavins in two kinds of tea is ShouMei> BaiMudan>BaiHao YinZhen> MengDingGanLu>JunShan YinZhen>HuoShan HuangYa.Using solid phase micro extraction and steam distillation respectively combined with GC-MS instrument for volatile constituents in different yellow tea and white tea samples tocompare and analyze.Solid phase microextraction method: sample balance time is20min,head of extraction model is75μm CAR/PDMS, extraction temperature at70℃, extractiontime is60min and injection port desorption for5min. Water vapor distillation method:sample with homemade distilled water vapor distillation unit6h, distillate continuousextraction with ether three times, using anhydrous sodium sulfate to wipe off water, and thelight yellow components are obtained with the rotary evaporator. Experiment results showthat the components with relatively high percentage by the solid phase microextractiontechnology analysis are alcohols, ethers, aldehyde, etc.; The components with relatively highpercentage by water vapor distillation analysis are alcohols, phenols, more acid, olefin etc.Combining these two methods can analyze the volatile component in yellow tea and white teasamples comprehensively.