Characterization of the volatile compounds of huangjiu using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC x GC-TOFMS)

The profile of volatile compounds in huangjiu was elucidated by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. The column combination was optimized and good separation and ordered chromatograms were achieved. An extracted ion trace method was established for the orderly separated categories to improve the identification accuracy. A total of 267 compounds were identified. Among them, 86 constituents were positively identified with authentic standards and other 181 components were tentatively identified. Esters were the most abundant class and ketones, alcohols, aldehydes, and acids occupied significant proportion in number. The extraction efficiency of liquid-liquid extraction and head space solid-phase microextraction (HS-SPME) on specific compounds was compared and HS-SPME showed remarkable sensitive to most classes except furanones and lactones. Furthermore, some compounds that might have important contribution to huangjiu aroma were highlighted. This study could enrich our knowledge on huangjiu constituents and aroma. Practical applications The method present in this research is suitable to characterize the volatile constituents of huangjiu, and could also be used for component characterization of similar complex samples such as fermented alcoholic beverages and foods. Furthermore, the extraction efficiency of headspace solid-phase microextraction and liquid-liquid extraction on specific compounds were compared. HS-SPME showed remarkable sensitive to most classes except furanones and lactones. Liquid-liquid extraction could effectively make up the shortcoming of HS-SPME. This could help us to choose suitable extraction methods for analysis of specific compounds in alcoholic beverages. Several important aroma compounds, such as linalool, nerolidol, geranyl acetone, 2-pentyl-furan, and methanethiol were quantified and their contribution to huangjiu aroma were studied. This offers theoretical and technological basis for flavor regulation and control of huangjiu.