Investigation of the retronasal perception of palm wine (Elaeis Guineensis) aroma by application of sensory analysis and exhaled odorant measurement (exom).

The headspace profile of palm wine was evaluated by time-resolved sensory analysis showing significant changes of the diverse odour attributes with time after swallowing. Fruity and citrusy were the most intense aroma qualities perceived upon sample introduction into the mouth, while swallowing of the palm wine elicited a more acidic impression followed by citrusy and fruity nuances respectively. After swallowing, panelists described an increase in the nutty and popcorn-like aroma impressions. Based on these sensory observations, the retronasal aroma perception of palm wine was investigated by application of the modified Exhaled Odorant Measurement (EXOM)-approach. In EXOM analysis, odorants that are exhaled through the nose during food consumption and swallowing are collected and analysed by high resolution gas chromatography-olfactometry and mass spectrometry, respectively. EXOM results revealed an initial 24 odor-active compounds in the \'swallow\' breath with 23 of these odorants being identified on the basis of their odor qualities and intensities, as well as chromatographic and mass spectral data. Only 14 compounds were detectable in the exhaled breath 20 s after swallowing the palm wine and 11 of these were subsequently identified. Generally, the identified odorants belonged to very diverse odorant substance classes such as heteroaromatic compounds, esters, alcohols, carbonyl and thio compounds and many more. Among these, higher persistence intervals in the exhalation breath were obtained for the buttery smelling compounds butan-2,3-dione and 3-hydroxy-butan-2-one (acetoine), 3-isobutyl 2- methoxypyrazine with bell pepper-like aroma impression, the malty smelling 2- and 3-methylbutanols, and the coconut-like smelling γ-dodecalactone. The popcorn-like smelling 2-acetyl 1-pyrroline, the fresh flowery linalool and two unknown compounds with citrusy and buttery aroma impressions were only detectable at 20 s after swallowing. Dynamic changes were also observed in retronasal sensory evaluations that were attributed to specific palm wine odorants. Accordingly, both sensory and analytical data on retronasal aroma perception of palm wine monitored the dynamic flavour changes during palm wine consumption. Keywords: Retronasal, EXOM, swallow breath, 2-acetyl 1-pyrroline African Journal of Food, Agriculture, Nutrition and Development Vol. 9 (2) 2009: pp. 793-81