Wuliangye is one of the most famous baijiu in China. Several hundreds of esters have been identified in Wuliangye baijiu, and these esters are abundant. Their aromas are similar, which makes it challenging to analyze other compounds with unique aroma quality. Thus, it is desirable to fractionate the aroma extract into subgroups based on functional group or polarity to simplify the analysis. However, the high alcohol content in aroma extract often deteriorates fractionation efficiency on normal phase chromatography. In this study, a new approach was attempted to achieve simultaneous aroma extraction and fractionation using tandem LiChrolut EN and silica gel solid-phase extraction (SPE) columns. The baijiu sample (10 ml, diluted in 40 ml of water) was first pass through the LiChrolut EN (1.0g) column. After dried with air, the LiChrolut EN (1.0g) column was connected with a silica gel (5.0g) SPE column with anhydrous Na<sub>2</sub>SO<sub>4 </sub>(10.0g) in between. The aroma compounds were eluted from the LiChrolut EN column and simultaneously fractionated on the silica gel column with increased solvent polarity (40ml of each fraction). The simultaneous extraction and fractionation enabled the collections of all esters in less polar fractions, and the acids, alcohols, pyrazines, furans, phenols, hydroxy esters, and other compounds in the more polar fractions. This method successfully solved esters' interference with other aroma analysis in baijiu. It has the advantages of integrating adsorption and fractionation, fast and straightforward operation, low solvent consumption, and minimum selective extraction and adsorption for aroma compounds. This technique was used to study the polar aroma compounds in Wuliangye, Moutai, and Fenjiu baijiu.

Tandem solid-phase extraction columns for simultaneous aroma extraction and fractionation of Wuliangye and other baijiu

ACS Spring Meeting 2021

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