基于GC-MS和PCA分析黑毛茶高湿霉变过程挥发性组分

Analysis of Volatile Compounds of Mildewed Raw Dark Tea Exposed to High Humidity Based on GC-MS and PCA

以同一批黑毛茶为原料,在高湿条件下进行促霉处理,按处理进程取样,同时收集市场霉变黑茶样本,采用同时蒸馏萃取结合气相色谱-质谱联用技术分析其挥发性组分,结合黑茶香气研究进展进行分析。结果表明:黑茶霉变样品中检出23种共有组分,38种人工霉变样品共有组分,43种自然霉变样品共有组分。棕榈酸、六氢法呢基丙酮、异植醇、叶绿酸、亚油酸和亚麻酸甲酯为霉变黑茶样品的主要组分。主成分分析法考察霉变黑毛茶风味的挥发性组分,结果表现为蘑菇醇、异植醇、叶绿醇、2,3-辛二酮、硬脂酸、壬醛、长叶烯、邻苯二甲酸二异丁酯、β-环柠檬醛、2,6-二甲基环己醇、芳樟醇与第1主成分高度正相关。该类组分呈味特性为花香带油哈味及泥土气味,这与感官审评的风霉味存在关联。

Six raw dark tea samples from the same batch were exposed to a high humidity environment to induce mildew.Besides, two naturally mildewed samples were collected from the market. The volatile components of all these samples were analyzed by simultaneous distillation extraction(SDE) combined with gas chromatography-mass spectrometry(GC-MS) and were evaluated based on the existing literature data on dark tea aroma. The results showed that a total of 23 volatile components were detected in all samples. A total of 38 and 43 volatile compounds were common to the artificially mildewed samples and the naturally mildewed ones, respectively. Palmitic acid, hexahydrofarnesyl acetone,isophytol, chlorophyllic acid, linoleic acid and methyl linolenate were the main volatile components of mildewed dark tea samples. The principal component analysis performed on the aroma components of mildewed dark tea showed that 1-octen-3-ol, isophytol, phytol, 2,3-octanedione, octadecanoic acid, nonanal, longifolen, phthalic acid diisobutyl ester,β-cyclocitral,2,6-dimethylcyclohexanol and linalol were highly positively correlated with the first principal component, which were responsible for the floral aroma with rancid and earthy odor and were related to the mildew flavor of sensory evaluation.