桂花红茶窨制技术及香气成分HS-SPME/GC-O-MS分析

为了探究桂花红茶的最佳窨制工艺及特征香气成分，设置正交试验并采用顶空固相微萃取结合GC-O-MS技术分析香气成分。由正交试验和感官审评可知：最佳窨制工艺为花茶配比3:10、窨制3次、每次窨制4 h；GC-MS分析表明桂花红茶吸附的香气成分主要有环己烯醇、壬醛、丙位癸内酯和植酮等4种，窨制过程增加的其它香气成分有：1-辛烯-3-醇、2-甲基-2-壬烯-1-醇、4-氯-双环[2.2.1]庚-2-酮、3-甲基-2-呋喃甲基丁酸酯、正戊酸己酯、正戊酸叶醇酯、丁酸苯乙酯等7种，推测这11种成分是桂花红茶香气形成的主体成分；GC-O结果表明：其中壬醛有油脂和甜橙香，丙位癸内酯有愉快桃子香，1-辛烯-3-醇有干草香，正戊酸叶醇酯有奶油香、果香，丁酸苯乙酯有蜜甜香，认为这5种成分是桂花红茶表现桂花香的特征性成分；此外，桂花红茶窨制过程中醇类物质相对含量显著降低，而酮类和酯类成分明显增加。
To investigate the optimal scenting technology and the characteristic aroma components of sweet-scented osmanthus black tea, orthogonal experiments were carried out and the aroma components were analyzed by using headspace solid phase microextraction (HS-SPME) combined with Gas Chromatography-olfactometry-mass Spectrometry (GC-O-MS) technique. The results of the orthogonal test and sensory evaluation showed that the optimal scenting conditions were: The osmanthus-black tea ratio, 3:10, tanning three times with each lasting 4 hours. The GC-MS analysis revealed that the aroma components adsorbed into the sweet-scented osmanthus black tea were mainly four compounds cyclohexenol, nonyl aldehyde, γ-decalactone and 6,10,14-trimethyl-2-pentadecanone. The newly generated aroma components during the scenting process were mainly 1-octene-3-ol, 2-methyl-2-nonen-1-ol, 4-chloro-bicyclo [2.2.1] heptan-2-one, 3-methyl-2-furanmethylbutyrate, hexylpentanoate, trans-2-hexenyl pentanoate, and phenethyl butyrate. These results suggest that these 11 compounds were the main aroma components of osmanthus black tea. The GC-O analysis revealed that nonyl aldehyde exhibited oily and sweet orange odor, γ-decalactone possessed pleasant peach fragrance, 1-octene-3-ol had hay fragrance, trans-2-hexenyl pentanoate had creamy and fruity aroma, and phenethyl butyrate had honey sweet aroma. These five substances may be the characteristic aroma components responsible for the osmanthus fragrance of osmanthus black tea. In addition, the relative contents of alcohols significantly decreased while the contents of ketones and esters increased significantly during the scenting process.