Evaluation of three gas chromatography-olfactometry methods: Comparison of odour intensity-concentration relationships of eight volatile compounds with sensory headspace data

Three gas chromatography-olfactometry methods, i.e. dilution analysis, detection frequency method and posterior intensity method, were evaluated for attribution of odour potency to eight volatile compounds at seven concentration levels. Six serial 1:5 dilutions of a solution consisting of 2-butanone, diacetyl, ethyl acetate, 3-methyl-1-butanol, ethyl butyrate, hexanal, 2-heptanone, α-pinene in pentane were analysed by gas chromatography-olfactometry. In addition, sensory odour intensity of sunflower oil solutions of the compounds at eight concentration levels were determined and related to their headspace concentrations. Posterior intensities correlated reasonably well with sensory odour intensities. Detection frequency data were also highly correlated, whereas dilution analysis led to more diverting results. A large variance among subjects was observed. Therefore, a group of assessors is considered a prerequisite for reliable gas chromatography-olfactometry analysis.