顶空固相微萃取结合气相色谱-质谱联用法对3种洋葱挥发性风味成分的分析

为研究洋葱挥发性成分，利用顶空固相微萃取法提取洋葱的挥发性风味成分，通过气相色谱-质谱联用法分析测定，以总峰面积和化合物个数为指标考察萃取纤维头、萃取温度、萃取时间和解吸时间4个因素对萃取效果的影响，得出最优萃取条件为:萃取纤维头50/30 μm DVB/CAR/PDMS，萃取温度60 ℃，萃取时间60 min，解吸时间5 min。利用最优萃取条件对三种色泽洋葱挥发性风味成分进行分析鉴定。结果表明:三种色泽洋葱共鉴定得到挥发性风味物质61种，其中白皮、红皮、黄皮洋葱分别测到37、40、49种挥发性成分，相对含量分别占流出组分总量的70.29%、81.92%、79.03%。61种挥发性成分中含硫化合物27种、醛类13种、醇类13种、酮类4种，其他4种。三种色泽洋葱的共有挥发性成分有22种，其中含硫化合物占比较大，特别是二异丙基二硫醚和(E)-1-丙烯基-2-丙烯基二硫醚相对含量的总和在三种色泽洋葱的挥发性成分中占比率都超过了20%，对形成洋葱特征风味贡献较大。红皮和黄皮洋葱的含硫化合物的相对含量远高于白皮洋葱，红皮洋葱中2-甲基-2-戊烯醛相对含量高于白皮和黄皮洋葱。

Analysis of Volatile Flavor Components in Three Onion by Headspace Solid Phase Microextraction Combined with Gas Chromatography-Mass Spectrometry

In order to study the volatile composition of onion, the volatile flavoring substances of the onion were extracted by headspace solid phase microextraction and determined by gas chromatography-mass spectrometry. The effects of extraction fiber head, extraction temperature, extraction time and desorption time on the total peak area and the number of effective compounds were investigated. The optimum extraction conditions were determined as follows: Extraction fiber 50/30 μm DVB/CAR/PDMS, extraction temperature 60 ℃, extraction time 60 min and desorption time 5 min. Under the optimum experimental conditions, the volatile compounds of onion with three different colors were analyzed and identified. The results showed that a total of 61 kinds of volatile flavor compounds were identified. A total of 37, 40 and 49 volatile flavor compounds were detected in the white, red, and yellow onions, respectively, and the peak area content of these volatile flavor compounds accounted for 70.29%, 81.92% and 79.03% of the total volatile components, respectively. In the 61 volatile flavor compounds, 27 were sulfur compounds, 13 were aldehydes, 13 were alcohols, 4 were ketones and 4 were others. There were 22 kinds of volatile components in the three color onions, of which sulfur-containing compounds account for a relatively large proportion, especially the relative content of diisopropyl disulfide and (E)-1-propenyl-2-propenyl disulfide. The sum of the volatile components of the three color onions accounted for more than 20%, which contributed a lot to the formation of the characteristic flavor of onions. The relative content of sulfur compounds in red and yellow onions was much higher than that of white onions. The relative content of 2-methyl-2-pentenoaldehyde in red onions was higher than that of white and yellow onions.