Recovery of aroma compounds from Zhenjiang aromatic vinegar by supercritical fluid extraction

Zhenjiang aromatic vinegar, which is produced from sticky rice through solid-state fermentation, is highly prized as one of the four famous China-style vinegars, owing to its unique flavour. In this study, a method of supercritical fluid extraction (SFE) was used for the first time to recover aroma compounds from Zhenjiang aromatic vinegar. For this purpose, the optimal conditions for the extraction of aroma compounds by SFE were determined as follows: CO2 flow rate, 25 L h(-1); extraction time, 2 h; extraction pressure, 35 MPa; and extraction temperature, 323 K. Using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis, a total of 49 and 44 aroma compounds were identified in Zhenjiang aromatic vinegar and its SFE extract, respectively. Acetic acid, ethyl acetate, furfural, phenethyl alcohol, tetramethyl-pyrazine, 3-hydroxybutanone and benzaldehyde were the main aroma compounds in the vinegar and its SFE extract. SFE is a fast and sensitive method to recovery aroma compounds from the vinegar.