The feasibility of the discrimination of Chinese rice wines with respect to their geographic origin and wine age using volatile profiles and chemometric methods was investigated. Stir bar sorptive extraction with thermal desorption and gas chromatography-mass spectrometry (SBSE-TD-GC-MS) was used for the determination of volatile compounds. A total of 63 volatile compounds were identified, including 30 esters, 9 alcohols, 9 aldehydes, 7 acids, 4 ketones, 3 volatile phenols and 1 miscellaneous compound. The major compounds in Chinese rice wine were ethanol, isoamyl formate, ethyl acetate, diethyl succinate, phenylethyl alcohol, benzaldehyde, ethyl lactate, 2-butanol and ethyl butyrate. Principal component analysis (PCA) and cluster analysis (CA) were used to characterize the different Chinese rice wine samples by geographic origin and wine age. The PCA results showed that the characterization of Chinese rice wine by SBSE-TD-GC-MS was highly related to geographic origin and wine age.The CA results indicated that geographic origin had more of an effect than wine age on the character of Chinese rice wine, and that 5-year old wines had a transition of flavor. The results showed that SBSE-TD-GC-MS together with chemometric methods could provide a practical reference for the characterization of Chinese rice wines.Keywords: Chinese rice wine, wine age, geographic origin, classification, chemometric methods
IntroductionChinese rice wine, in addition to wine and beer, is one of the most ancient wines in the world (Wang and Yi, 2001). It is fermented from rice with wheat Qu (source of microorganisms and crude enzymes) and yeast (Mo et al., 2010). The best-known Chinese rice wine is Shaoxing rice wine. Comparable to the European Denomination of Origin, the National Standard of China GB/T
17946-2008 (Shaoxing rice wine) defines that Shaoxing rice wine isfermented from high quality glutinous rice and wheat as well as water from Mirror Lake in the region near Shaoxing city in the Zhejiang province, China. Before their sale, certain Chinese rice wines are stored in ceramic pottery to age. The aged Chinese rice wines have a smoother, mellower and richer mouth feel and a more harmonious flavor than the non-aged wines (Shen et al., 2012).To protect producers by guaranteeing their reputation and to protect consumers by ensuring consistent character of the wine, research has been conducted to discriminate wines by their geographic origin or their wine age/vintage. The volatile compounds are centrally important to ensuring the identity of wine (Pereira et al., 2010), as their contents depend on the brewing technology, geographic origin and aging process (Tredoux et al., 2008). Much attention has been paid to the volatile profiles of wine, including research on the classification of liqueur wines (Pereira et al., 2010), the discrimination of white wine (Hernanz et al., 2009), the characterization of Vino (Gil et al., 2006) and the classification of red wine (Zhang et al., 2010; Alejandro Calleja and Falqué, 2005).Sample preparation ...