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.
