Relationship between the terpene enantiomeric distribution and the growth cycle of lemon fruit and comparison of two extraction methods

Abstract

Lemon essential oil is one of the most widely used natural flavours in the food and beverage industries. Knowledge of the enantiomeric ratio in flavours has gained relevance because they may indicate differences in their organoleptic characteristics or their authenticity. The study was carried out during the growth of the lemon fruit to evaluate the possible variations of the enantiomeric ratio of four characteristic terpenes: α-pinene, β-pinene, linalool and limonene. Two extraction methods were applied to extract the terpenes: simultaneous distillation–extraction at reduced pressure (V-SDE) and solid-phase microextraction; the results were equivalent whatever the method applied. In both cases, the target compounds were obtained from the lemon peel. Enantiomeric profiles were obtained by enantioselective multi-dimensional gas chromatography–mass spectrometry (enantio-MDGC-MS). Consistent enantiomeric ratios of α-pinene, β-pinene and limonene were observed; however, the enantiomeric ratio of linalool varied significantly according to the growth stage of the lemons in a spontaneous and natural way.