Relationship between sensory profiles and odor-active compounds detected by Gas-Chromatography olfactometry

Cheese flavour has been widely studied and key-aroma compounds identified. However the strategies involved were mostly correlation studies between quantitative measurements of aroma compounds and either gas chromatography olfactometry (GC-O) data or sensory data. These correlations do not take in account the differences in the Stevens’ slopes relating sensory perception and concentration and perception thresholds. The objective of this study was thus to explain sensory perception of cheese by the intensity of single molecules measured by GC-O analysis. Seven commercial semi-hard cheeses were evaluated by a sensory descriptive analysis. Thirteen odour attributes were evaluated by a panel of trained judges. The volatile compounds of the cheeses were then extracted by dynamic headspace and the odour active compounds were detected by GC-O by eight trained judges applying the Osme technique which accounts for Stevens’ slopes. The odour active compounds were then identified by a two-dimensional GC-heartcut procedure (GC-GC-MS/O). Finally the intensity scores for the sensory attributes and for the odour-active compounds were analysed by partial least squares (PLS) to find correlations between the two datasets. The PLS showed strong correlations between the sensory attributes and the odour active compounds, for example the buttery attribute evaluated by the sensory profile were strongly correlated with 2,3-butanedione and 3-hydroxy-2-butanone known for their buttery odours and the cheesy sensory attributes were very well correlated with butanoic acid and isovaleric acid known for their cheesy odours. This correlation study has given us great opportunities to apprehend sensory attributes when accounting for Steven’s Power Law and perceptions thresholds of odour active compounds. However, a limit of GC-O analysis is to not accounted for perceptual interactions such as masking and synergy among odorants. This will be further investigated by omission experiments