The main purpose of this study was to determine the volatile composition of Zhenjiang aromatic vinegar, one of the four famous China-style cereal vinegars, by using headspace solid-phase microextraction (HS-SPME)/gas chromatography-mass spectrum (GC-MS) and chemometrics. For this purpose, the HS-SPME sampling method for the volatile compounds of Zhenjiang aromatic vinegar was optimized by a second-order rotatable central composite experimental design (CCD). A HS extraction of the volatile compounds by incubation on a 65 mm thickness polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre during 44.2 min at 69.5 C with 1.9 g NaCl add gave the most effective and accurate extraction. By the optimized method, a total of 58 volatile compounds, including 9 alcohols, 13 acids, 16 esters, 5 aldehydes, 4 ketones and 8 heterocycle compounds, were identified from 13 aromatic vinegar samples manufactured in Zhenjiang region. By principal components analysis (PCA), the thirteen vinegar samples were classified into 3 groups, and 10 volatile compounds were chosen as characteristic compounds of Zhenjiang aromatic vinegars.

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: CO 2 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. Recovery of vinegar aroma by supercritical CO 2 Z.-M. Lu et al.