Study on Volatile Components in Alcohol Solute in Pu-erh Tea by Gas Chromatographic-Mass Spectrometric Fingerprint Method

The alcohol-soluble substances were extracted with the ultrasonic extraction using ethanol as the solvent from Pu-erh tea 7542, used as the reference sample.The gas chromatographic-mass spectrometric (GC-MS) fingerprint of alcohol-soluble substances in Pu-erh tea has been established, and the similarity calculation and principal components were analyzed.The results showed that the optimal extraction method of alcohol-soluble substances in Pu-erh tea were as follows:50 mL 95% ethanol was used as the solvent and ultrasonically extracted for 30 min? the optimum headspace oscillator temperature was 110℃ with the oscillation duration for 20 min.The similarity of the volatile constituents GC-MS fingerprint of alcohol-soluble substances in Pu-erh tea and the reference fingerprint was between 0.706 and 0.906, which showed that the volatile constituents had slight differences in the 9 different ages and batches of Pu-erh teas, but the peak area percentages of the common components varied greatly.Through the principal component analysis of the common components of volatile components of the alcohol-soluble substances in 9 different ages and batches of Pu-erh tea 7542, two components, 2-hydroxymethyl-2-methyl-pyrrolidine-1-carbaldehyde and N-butylbenzene sulfonamide extracted.Their eigenvalue were greater than 1 and the contribution rate was 90.2%, which can better reflect the main volatile components in the alcohol solute of Pu-erh tea 7542 series.Therefore, the assay of 2-hydroxymethyl-2-methyl-pyrrolidine-1-carbaldehyde and N-butylbenzene sulfonamide can decide the quality of different ages and batches of Pu-erh teas.