Gas chromatography/sniffing port analysis of aroma compounds released under mouth conditions

The release of aroma compounds from rehydrated French beans in an artificial mouth system and in the mouths of 12 assessors was studied by gas chromatography combined with flame ionisation detection and sniffing port detection. In an artificial mouth system, volatile compounds were isolated under mouth conditions, such as temperature, salivation, and mastication. No significant differences were determined between the aroma release from the beans in the artificial mouth and release in the mouths of assessors. However, both the real and artificial mouth systems differed significantly from a purge-and-trap and a dynamic headspace system in aroma release. In order to study aroma release over time, volatile compounds were isolated from rehydrated French beans for 1, 1.5, 3 and 12 min in the artificial mouth system and analysed by gas chromatography/sniffing port analysis. 2- Methylpropanal, 2-/3-methylbutanal, hexanal, 2-methyl-2-butenal, 1-octen-3- one, and dimethyl trisulphide possessed detectable odours when isolated from the French beans in the artificial mouth for all time periods. The odour active compounds 2-/3-methylbutanal and hexanal were shown to be released at a constant rate. Different sampling times resulted in identical selections of aroma compounds, while mutual proportions were retained. (C) 2000 Elsevier Science B.V.