Panellists were individually seated in well-ventilated booths and
were each presented with one blind-coded, 3-AFC set of samples that
consisted of one level of the test sample and two blank samples.
The order of presentation of the samples within a set of three samples was
randomised. In addition to determining whether there was an odd
sample in the set, when an odd sample was chosen correctly,
panellists were also required to give a rating on the level of difference
of the odd sample from the other two based on a scale from 1 to 10
with 1=“least different” and 10=“most different.” On each
assessment day, six levels of indole or skatole were presented to the
panellists in ascending order in six panel sessions separated 20 min
apart. The assessments were replicated five times over a period of
5 weeks and were all carried out under red lights