The mixture was then centrifuged
at 4 C (9000g, 15 min). After the dehydration by anhydrous
sodium sulphate, the pooled organic extract was reduced to 5 mL
in a Kuderna Danish concentrator fitted with a Snyder column
(Supelco, St Quentin, France) and then to 0.5 mL under a gentle
stream of nitrogen. The extracts were subsequently stored at
20 C in a glass vial equipped with Teflon-lined cap before the
analysis. Each sample was extracted in triplicate and the concentration
of volatiles, as 4-nonanol equivalents, was obtained as a
means of three repetitions.