Abstract
Since Taiwan government permitted local production of rice wines by private companies, more rice wines with poor quality have been sold in marketplaces. Some rice wines appear in market with fake labels, whereas others might be adulterated, denatured or industrial alcohol, used for profit by cost reduction. Moreover, it is too difficult to distinguish quality of rice wines by human senses. Therefore, it is necessary to develop a reliable method to monitor rice wines sold in marketplaces. In the first part of this research, we used HS-SPME (headspace- solid phase microextraction) and combined with GC/IRMS (gas chromatograph/isotope ratio mass spectrometer) to measure δ13C of ethanol. According to the literature, rice belongs to C3 plants. Its δ13C should be in between -24 and -32 ‰. Furthermore, we used rice wine from TTL (Taiwan Tobacco & Liquor Corporation) as reference sample, and the 13C value of it is -29.03‰. Thus, we analyzed 34 rice wine samples, and classified them into three groups. (1) δ13C less than -25 ‰ as high rice content, (2) δ13C from -25 ‰ to -20 ‰ as medium rice content, (3) δ13C greater than -20 ‰ as no rice content. In the second part of this research, we used DLLME (dispersive liquid-liquid microextraction) as pretreatment method and combined with GC/MS (gas chromatograph/mass spectrometer) to identify the components of rice wines. Finally, we determined 57 analytes and obtained gas chromatograms, which could be used to differentiate brands and origins of rice wines.