Analysis of Volatile Compounds in “XihuLongjing” Tea by Stir Bar Sorptive Extraction Combine with Gas Chromatography-Mass Spectrometry
WANG Mengqi, ZHU Yin, ZHANG Yue, SHI Jiang, LIN Zhi, Lü Haipeng
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In this study, stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile compounds of “XihuLongjing” tea. SBSE parameters including stir bar type, extraction temperature, extraction time, tea-to-water ratio, agitation rate and ionic strength were optimized by one-factor-at-a-time and orthogonal array design methods in order to establish the SBSE-GC-MS method. The overall accuracy of the experiment was satisfactory (recoveries of 115.11% and 108.99% at high and low spiked concentration levels, respectively) and the relative standard deviation (RSD) for repeatability was 8.23% (n = 5). The results showed that the volatile aroma compounds could be extracted and adsorbed to the greatest extent under the following conditions: using polydimethyl siloxane (PDMS) twister as an extraction medium, tea-to-water ratio 60:1 (mg/mL), NaCl concentration 5%, hot water temperature 80 ℃, extraction time 90 min, and agitation rate 1 250 r/min. When representative “XihuLongjing” tea samples were analyzed by the SBSE-GC-MS method, a total of 173 volatile compounds were identified, including 3 enols, 11 alkenes, 37 alkanes, 15 aldehydes, 4 olefine aldehydes, 2 ethers, 17 alcohols, 22 esters, 5 lactones, 9 allyl esters, 5 ketones, 16 ketones, 3 organic acids, 3 sulphur compounds, and 3 nitrogen heterocyclic compounds, 3 oxygen heterocyclic compounds, and 15 aromatic hydrocarbons. Eventually, we concluded that the volatile aroma compounds in “XihuLongjing” tea could be extracted well by SBSE.