Enantiomers sensory evaluation

Enantioselective gas chromatography can provide three quite different kinds of information (1) the amount of each enantiomer present in a food, determined as the enantiomeric purity or the enantiomer excess, and the separation factor a for each pair of enantiomers (2) enantiospecific sensory evaluation using gas chromatography-olfactometry (GC-O) and (3) data used as part of an authenticity determination. 

Lehmann, D., A. Dietrich, U. Hener, and A. Mosandl, 1995. Stereoisomeric avour compounds LXX, 1-p-menthene 8 thiol Separation and sensory evaluation of the enantiomers by enantioselective gas chromatography/olfactometry. Pl tochenL nal., 6 255. 

Carvone is one of the classic examples of odor differences between enantiomers. In 1971, Friedman and Miller (311) interconverted the enantiomers using the reactions shown in Fig. 8.50 and proved conclusively that the spearmint character of /-carvone and the dill-caraway character of intrinsic properties of the respective enantiomers and were not due to trace impurities. Thus epoxidation of /-carvone (242) gave (244), which could be reduced to d-trans-car/eol (245) and that oxidized to well-constructed sensory evaluation... 

Alkylcarbonic acids have been separated into their enantiomers without any deriva-tization and their sequence of elution was assigned by co-injection with enantio pure references [17]. Latest results on stereoselective flavour evaluation revealed characteristic sensory properties for all the enantiomers of 2-alkylbranched acids, esters and corresponding alcohols. Tremendous differences between the mirror images of 2-methylbutanoic acid have been found. While the R-enantiomer exhibits a penetrating, cheesy-sweaty odour, the S-enantiomer emits a pleasant sweet and fine fruity note [87, 88]. All commercially available homologues of 2-methylbutanoic acid esters and 2-methylbutyl acetate are simultaneously stereoanalyzed, using heptakis (2,3-di-O-methyl-6-0-tert-butyldimethylsilyl)-P-cyclodextrin (DIME-P-CD) in PS 268 as the chiral stationary phase [88] (Eig. 6.33, Table 6.19). 

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