Keywords: 
• 茉莉花 /
• 烘焙 /
• 香气成分 /
• 光电离 /
• 质谱 /
• 实时在线

Abstract: Due to the high specificity and high speed of mass spectrometer,on-line moni-toring of the roasting process by mass spectrometry has attracted increasing attention at present.In this work,fresh jasmine flowers were roasted in a home-made tube furnace, and the vaporized aroma components were monitored by an on-line low pressure vacuum ultraviolet photoionization time-of-flight mass spectrometry(VUV-PI-TOF MS)in real time.The jasmine flowers were roasted at four different temperatures(90,120,150 and 200 ℃),and the mass spectra of the roasting products were quickly obtained.Since PI produces little or no fragments,nearly all the mass peaks can be attributed to molec-ular ions.Products identification was fulfilled according to the previous GC/MS results.The contents of these substances had been reported to be positively correlated with the quality of jasmine flowers.The relationship between the roasting temperature and vari-ous releasing aroma components was studied by the temperature-programmed mode with a heating rate of 5 ℃/min.Water is abundant in jasmine flowers,whose signal strength first increased slowly,then kept stable and finally decreased slowly with the rise of roasting temperature from 40 to 170 ℃.During this process,the signal strength of most vaporized aroma compositions kept increasing and increased quickly at a temperature higher than 140 ℃.T he increasing rates of compounds such as acetone,butanone,ethyl acetate,phenylethyl alcohol,benzoate-cis-3-hexenyl and benzyl alcohol were higher than that of indole and benzyl alcohol.The time-evolved profiles of water and four main vaporized aroma compounds in jasmine flowers over 1 700 s were also investigated at 90, 120 and 150 ℃,respectively.With the elapse of time,all substances except butanone had the same trend at 90,120 and 150 ℃.They rose quickly within a short period of time,then maintained at a lower concentration for a long time.However,when the roasting temperature was 150 ℃,the signal of butanone appeared again at 1 500 s.The results showed that more aroma ingredients were lost at a higher temperature,which was bad for the preservation of jasmine flowers'quality.However,too low temperature was not favorable for the vaporization of water and the taste of toasted jasmine flowers would be bad.Therefore,90 ℃ is a highly-recommended roasting temperature.VUV-PI-TOF MS can be used for the evaluation of the roasting process of jasmine flowers, and offer guide for the industrial production.