Analysis of aroma compounds in dried red goji berries (Lycium sp.) after fractionation with countercurrent chromatography.

Capturing as many aroma compounds as possible in a sample is important, as aroma is a crucial factor for the acceptance of food by consumers. Here, we developed and applied a method for the detailed analysis of aroma compounds in dried red goji berries after fractionation by countercurrent chromatography (CCC). Tests with shake flask experiments of seven characteristic aroma compounds resulted in the solvent system n-pentane/dichloromethane/acetonitrile (20:4:20, v/v/v). After CCC separation with a pool of volatile fractions of goji berries obtained by solvent-assisted flavor evaporation (SAFE), the CCC fractions were Vigreux-concentrated and analyzed by gas chromatography with mass spectrometry (GC/MS). Altogether, 49 aroma compounds were detected after CCC fractionation. The parallel use of the conventional fractionation method via column chromatography enabled the detection of 45 aroma compounds. However, only 25 analytes were detected by both methods (24 exclusively by CCC and 20 analytes exclusively by conventional column chromatography). Unexpectedly, some aroma compounds were detected in virtually all CCC fractions. This indicated a particular effect in the CCC analysis of volatile compounds. Such a distribution across many fractions corresponds to a dilution effect which may be the reason that several volatiles could not be detected in the CCC fractions. Accordingly, the combination of both methods will provide the best information on the aroma compound profile.