Solvent-assisted stir bar sorptive extraction and gas chromatography-mass spectrometry with simultaneous olfactometry for the characterization of aroma compounds in Japanese Yamahai-brewed sake.

Yamahai-brewed sake, a Japanese alcoholic beverage brewed from rice and produced via natural lactic acid fermentation, has a complex and rich flavor compared with Sokujo-brewed sake, brewed with a general method using pure lactic acid. This study aimed to characterize the aroma compounds in Yamahai-brewed sake using solvent-assisted stir bar sorptive extraction (SA-SBSE) with gas chromatography-olfactometry/mass spectrometry (GC-O/MS) and to confirm the enhanced sensitivity of GC-O/MS with SA-SBSE compared with SBSE alone. SA-SBSE with GC-O/MS increased the number of detected odor-active compounds and improved the FD factor sensitivity of Yamahai-brewed sake. SA-SBSE-GC-MS analysis of three pairs of Yamahai-brewed and Sokujo-brewed sake showed higher polar aroma compound content in Yamahai-brewed sake with a low rice polishing ratio. Quantification of 11 characteristic aroma compounds with a wide range of log K values revealed that several compounds, including ethyl mandelate, ethyl 2-hydroxy-4-methylvalerate, and the newly identified γ-6-(Z)-dodecenolactone, were more abundant in Yamahai-brewed sake.