不同乳酸菌发酵杜仲叶水提液的香气成分分析

利用电子鼻辅助同时蒸馏萃取-气相色谱-质谱（Simultaneous distillation-extraction-gas chromatography-mass, SDE-GC-MS）联用技术研究不同乳酸菌（植物乳杆菌、德氏乳杆菌、嗜酸乳杆菌和嗜热链球菌）发酵杜仲叶水提液的主要香气成分差异性。SDE-GC-MS分析结果表明，未发酵液的挥发性成分共鉴定出31种，以醛类相对含量最高（14.3591%）；植物乳杆菌、德式乳杆菌、嗜酸乳杆菌和嗜热链球菌发酵后鉴定出的挥发性成分依次为45、38、51和43种，分别以酮类（18.8255%）、杂环类（25.7828%）、醇类（18.3376%）和醇类（14.1481%）相对含量最高。通过电子鼻分析，PCA和LoA主成分贡献率均大于95%，说明传感器识别效应和样品间的风味区分度较好。同时，ROAV分析结果显示，乳酸菌发酵增加了杜仲叶提取液关键香气成分含量，降低原本杜仲叶的青叶味。经乳酸菌发酵后的杜仲叶提取液，不仅挥发性成分数量较多，且关键香气成分含量增加显著，更有利于杜仲叶提取液香气提升。研究结果为杜仲叶产品后期研发提供了参考依据。

Analysis of Aroma Components in Water Extract of Eucommia ulmoides Leaf Fermented by Different Lactobacillus Species

In order to research the effect of different Lactobacillus species on the aroma components of water extract of Eucommia ulmoides leaf,electronic nose(E-nose)and simultaneous distillation extraction(SDE)combined with gas chromatography-mass spectrometry(GC-MS)was used to analyze the volatile flavor composition of water extract of Eucommia ulmoides leaf fermented by Lactobacillus plantarum,Lactobacillus bulgaricus,Lactobacillius acidophilus and Streptococcus thermophilus.The results of SDE-GC-MS showed that 31 aroma components were identified in unfermented samples,with aldehyde being the most abundant constituents(14.3591%).The volatile components identified by Lactobacillus plantarum,Lactobacillus bulgaricus,Lactobacillius acidophilus and Streptococcus thermophilus after fermentation were 45,38,51 and 43,with ketones(18.8255%),heterocycles(25.7828%),alcohols(18.3376%)and alcohols(14.1481%)as the highest relative contents,respectively.In principal component analysis(PCA)and Loading Analysis(LoA)the cumulative contribution of the first 2 principal components accounted for greater than 95%,suggesting that the E-nose sensors had good recognition performance and discrimination between samples on the basis of their flavor characteristics was excellent with clear distinctions.The relative odor activity value(ROAV)indicated that Lactobacillus fermentation increased the content of key aroma components in Eucommia ulmoides leaf extract,and reduced its green leaf flavor.After Lactobacillus fermentation,the extract of Eucommia ulmoides leaf not only had more volatile components,but also significantly increased the content of key aroma components,which was more conducive to the improvement of aroma in the extract of Eucommia ulmoides.The results of this study provide a reference for the later research and development of Eucommia ulmoides leaf.