Analysis of volatile compounds of sour guava (Psidium acidum [DC.] Landrum) using headspace-solid phase microextraction

Application of headspace-solid phase microextraction combined with gas chromatography coupled to flame ionization, mass spectrometry and olfactometric detectors was used to analyze, for the first time, the volatile compounds of sour guava (Psidium acidum [DC.] Landrum) and to estimate the most odor-active compounds. According to the global odor trapped in the fiber, a comparison between 100 m PDMS, 65 m PDMS/DVB, 50/30 m DVB/CAR/PDMS and 85 m CAR/PDMS fibers showed that the 50/30 m DVB/CAR/PDMS fiber was the most adequate to analyze the volatile compounds of this fruit. The analyses led to the identification of 128 compounds, including 49 esters (88.7 % of the total volatile composition), 20 terpenes (0.9 %), 14 alcohols (3.8 %), 14 aldehydes (0.7 %), 13 acids (2.4 %), 7 ketones (0.5 %), 5 hydrocarbons (0.1 %), 3 oxides (2.4 %), 2 furans (0.1 %) and one S-compound (traces). Major components (> 8 %) were (Z)-3-hexenyl acetate, butyl butanoate, butyl acetate, methyl octanoate, methyl hexanoate and hexyl acetate. Twenty-six of them were considered as odor-active compounds and contribute to the typical sour guava aroma, from which the most important were (Z)-3-hexenyl acetate, hexyl acetate, 3-methylbutyl butanoate and (Z)-3-hexenyl hexanoate. The relevance of aliphatic esters, particularly those related to C6.