Optimization of Headspace Solid-Phase Microextraction Conditions for the Identification of Volatiles Compounds from the Whole Fruit of Lemon, Lime, Mandarin and Orange

An optimum method has been developed for extracting volatile organic compounds (VOCs) which contribute to the aroma of different species of citrus fruit (orange, lemon, lime, and mandarin). Headspace solid phase microextraction (HS-SPME) combined with gas chromatography (GC) coupled with flame ionization detection (FID) is used as a very simple, efficient and nondestructive extraction method. A three phase 50/30 μm PDV/DVB/CAR fibre was used for the extraction process. The optimal sealing time for volatiles reaching equilibrium from whole fruit in the headspace of the chamber was 20, 16, 8 and 16 hours for lemon, lime, mandarin, and orange respectively. Optimum fibre exposure times for whole fruit were 2, 4, 2 and 2 hours for lemon, lime, mandarin, and orange respectively. Three chamber volumes (500, 1000 and 2000 ml) were evaluated for the collection of VOCs with the 500 ml chamber being selected. The 500ml chamber produced the highest quality peak areas and quantity of extracted volatiles. As a result of fruit respiration, the percentage of oxygen (O2) of all citrus fruit species in 500 ml chamber decreased from 21.8% to 18.8% in the 20 hours sealing time, while carbon dioxide (CO2) contents increased to 2.9% also in the 20 hours sealing time. The results of this study showed the feasibility of this technique for identifying VOCs from four of the citrus fruit species and its potential as a routine method for physiological studies on citrus fruit or on other fruit species.