Identification of aroma compounds in Chinese 'Yanghe Daqu" liquor by normal phase chromatography fractionation followed by gas chromatography olfactometry

Aroma compounds in Chinese 'Yanghe Daqu' liquor were investigated with normal phase chromatography fractionation followed by gas chromatography-olfactometry (GC-O). Yanghe Daqu liquor was extracted with Freon 11, and then separated into acidic and neutral/basic fractions. The neutral/basic fraction was further separated into four fractions, using silica gel normal phase chromatography. Aroma compounds in each fraction were analysed by GCO and GC-MS. The results showed that Yanghe Daqu liquor aroma was mainly contributed by esters and fatty acids. Among them, ethyl hexanoate (Osme value =15), ethyl butanoate (Osme value >= 14) were probably the most important esters, based on their Osme values. In addition, ethyl octanoate, 3-methylbutyl hexanoate and ethyl pentanoate could be important (Osme values 40). Acids with high Osme value included hexanoic, butanoic, 3-methylbutanoic and pentanoic acids. They contributed to sour, acid, cheesy and sweaty aromas. I-Hexanol and 3-methylbutanol also had high Osme values. In addition, 4-ethylguaiacol, 4-methylguaiacol and 4-ethylphenol were identified in Yanghe Daqu liquor and they contributed to clove, sweet, smoky and goaty aromas. 1,1-Diethoxy ethane, 1, 1-diethoxy-2-methylpropane and 1,1-diethoxy3-methylbutane were identified and they gave fruity and floral aromas. Copyright (c) 2005 John Wiley & Sons, Ltd.