3种不同加工方式对桑叶茶挥发性成分的影响

目的 通过对桑叶茶的香气成分进行分析,揭示3种加工方式对桑叶茶挥发性成分影响的规律。方法 采用气相色谱-离子迁移谱仪(gas chromatography-ion mobility spectrometry,GC-IMS)比较分析通过炒制、自然发酵和助剂发酵3种不同方式制作的桑叶茶的挥发性成分差异。结果 GC-IMS结果显示自桑叶茶样品中检测出72种挥发性成分,其中的36种成分被定性,主要为醛类、酮类、醇类和酯类等物质,其中:醛类物质24种、酮类物质4种、醇类物质4种、酯类物质1种,另外还有甲基吡嗪、二甲基三硫和2-戊基呋喃。相比炒制桑叶茶,发酵桑叶茶样品中丙酮、2-丁酮、二甲基三硫、甲基吡嗪、2-戊基呋喃、2,3-丁二醇、乙酸乙酯和2-庚酮等物质含量显著增加;正丙醇、戊醛和戊醇等28种定性成分明显减少。结论 加工方式可显著影响桑叶茶的风味,炒制桑叶茶与发酵桑叶茶的挥发性成分差异明显,发酵桑叶茶能够形成甜香回甘的特色风味,有效祛除青草气味,改善桑叶茶的感官品质;自然发酵和助剂发酵的桑叶茶挥发性成分种类相同,仅物质含量存在差异。

Effects of 3 kinds of different processing methods on volatile components of mulberry leaf tea

Objective To analyze the aroma components of mulberry leaf tea, and to reveal the effects of 3 kinds of processing mode on the volatile components of mulberry leaf tea. Methods The volatile components of mulberry leaf tea prepared by frying, natural fermentation and auxiliary fermentation were compared and analyzed by gas chromatography-ion mobility spectrometry (GC-IMS). Results The GC-IMS results showed that 72 kinds of volatile components were detected in the mulberry leaf tea samples, 36 kins of which were characterized as aldehydes, ketones, alcohols and esters, among which: 24 kinds of aldehydes, 4 kinds of ketones, 4 kinds of alcohols and 1 kinds of ester, in addition to methyl pyrazine, dimethyl trisulfide and 2-pentylfuran. Compared with fried mulberry leaf tea, the content of acetone, 2-butanone, dimethyl trisulfide, methyl pyrazine, 2-pentylfuran, 2,3-butanediol, ethyl acetate and 2-heptanone and other substances was significantly increased in fermented mulberry leaf tea samples; 28 kinds of qualitative components such as n-propanol, pentanal and pentanol were significantly decreased. Conclusion The processing method can significantly affect the flavour of mulberry leaf tea. The volatile components of fried mulberry leaf tea and fermented mulberry leaf tea differ significantly, with fermented mulberry leaf tea being able to develop a characteristic flavour of sweetness and sweetness, effectively removing the grass smell and improving the sensory quality of mulberry leaf tea; the volatile components of naturally fermented and auxiliary fermented mulberry leaf tea are of the same type, with only the substance content differing.