Profiling of volatile compounds in Japanese sake stored in sherry casks using solid phase microextraction/gas chromatography/mass spectrometry analysis

Abstract

The combination of solid phase microextraction (SPME) and gas chromatograph-mass spectrometer (GC-MS) is frequently used for comprehensive analysis of aroma components in foods because it can be used to easily analyze volatile components, allowing saving of the amount of solvent used. In this study, SPME-GC-MS analysis of sake samples before and after sherry cask storage was performed to investigate the special flavor derived from sherry cask storage. A GC column with polyethylene glycol as the stationary phase, which is the first choice for volatile component analysis, was used. However, the peak of the acid having a carbonyl group was tailed due to its bond with the hydroxyl group of the stationary phase. In the analysis of sake samples, a large and tailing peak derived from the large amount of fatty acids in Japanese sake was observed. Additionally, it was not possible to analyze other co-eluting components. To overcome this problem, a novel extraction condition was examined using SPME and tris (hydroxymethyl) aminomethane (Tris). By adding Tris solution to sake, the fatty acid peak was removed successfully, thereby facilitating analysis of the peaks of compounds co-eluting with fatty acids and comprehensive analysis of the aroma components in sake. Furthermore, a comparative analysis of sake before and after storage in sherry cask showed that levels of fatty alcohols, organic acid esters, fatty acid esters, and terpenes increased significantly after storage in sherry cask, suggesting that these ingredients might constitute the special flavor of sherry cask-stored sake.

Keywords: Barrel storage; Gas chromatography/mass spectrometry; Japanese sake; Sherry cask; Solid phase microextraction; Tris(hydroxymethyl)aminomethane.