动态顶空取样-大气压化学电离质谱原位实时监测发酵乳挥发性代谢产物

采用大气压化学电离质谱法，利用动态顶空取样技术对发酵乳生产过程中产生的挥发性代谢产物进行原位实时监测。从发酵开始后3.0～4.7h连续用质谱仪记录发酵乳挥发物的离子流信号，结果表明：2,3-丁二酮(m/z 104，M+H2O+·)在前4h信号较弱，4h后开始逐渐增大，4.2h后呈快速增大的趋势；乙酸乙酯(m/z 106，M+H2O+·)信号从发酵3h后开始呈逐渐增大趋势；苯甲醛(m/z 124，M+H2O+·)信号较平稳。发酵进行到6h的质谱图中质谱信号主要有乳酸(m/z 91，MH+和m/z 108，M+H2O+·)，2,3-丁二酮(m/z 104，M+H2O+·)，苯甲醛(m/z 107，MH+和m/z 124，M+H2O+·)，乙酸乙酯(m/z 89，MH+和m/z 106，M+H2O+·)，正已醛(m/z 101，MH+和m/z 118, M+H2O+·)，2-丙烯醛(m/z 74·M+H2O+·)等。未发酵的纯牛奶质谱图中有正己醛(m/z 101，MH+)，苯甲醛(m/z 107，MH+和m/z 124，M+H2O+·)，葵醛(m/z 174，M+H2O+·)等信号。动态顶空取样-大气压化学电离质谱技术具有快速、非破坏性等优点，在发酵食品的生产质量控制方面有一定的理论和实际应用价值。

In Situ Real-Time Monitoring of Volatile Metabolites of Fermented Milk by Dynamic Headspace Sampling-Atmospheric Pressure Ionization Mass Spectrometry

Volatile metabolites produced from fermented milk were monitored in situ real-time by atmospheric pressure dynamic headspace sampling coupled with chemical ionization mass spectrometry. The ion current signal of volatile metabolites was recorded during 3.0 h to 4.7 h after the start of fermentation. The signal of 2,3-butanedione (m/z 104, M+H2O+·) was weak in the first 4 h followed by a gradual increase, reaching a rapid upward trend after 4.2 h, the signal of ethyl acetate (m/z 106, M+H2O+·) began gradually increasing after 3 h, but the signal of benzaldehyde (m/z 124, M+H2O+·) remained relatively stable. The mass spectrum of 6 h fermented milk mainly included the signals of lactic acid (m/z 91, MH+ and m/z 108, M+H2O+·), 2,3-butanedione (m/z 104, M+H2O+·), benzaldehyde (m/z 107, MH+ and m/z 124, M+H2O+·), ethyl acetate (m/z 89, MH+ and m/z 106, M+H2O+·), hexanal (m/z 101, MH+ and m/z 118, M+H2O+·), acrolein (m/z 74, M+H2O+·), etc. Atmospheric pressure dynamic headspace sampling coupled with chemical ionization mass spectrometry has many advantages such as rapid and non-destructive and can be used for quality control in the production of fermented milk.