VOLATILE COMPOUNDS OF EIGHT SELECTED UNDERUTILIZED PLANTS BY HEADSPACE SOLID-PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHY

Volatiles have been used as potential natural therapeutic agents and additives in food formulation, especially because of their antimicrobial properties. Headspace solid phase micro extraction (HS-SPME) is widely used for the extraction of these compounds. Optimization of HS-SPME extraction factors allows adequate reproducibility and sensitivity. The aim of this study was to determine the profile of volatile compounds by HS-SPME combined with GC-MS and GC-FID of eight underutilized edibles plants, named Acmella oleracea, Eryngium foetidum,
Hibiscus acetosella, Hibiscus sabdariffa, Ocimum gratissimum, Pereskia aculeata, Portulaca oleracea and Xanthosoma sagittifolium. HS-SPME conditions were screened by PlackettBurman design, to estimate the significant factors affecting extraction efficiency. Assed variables and final concentration were: salt concentration (17.5%), temperature (65 °C), extraction time (40 minutes) and equilibrium time (12 minutes). Compounds identification was carried out by
GC–MS, comparing the mass spectra with the database of the National Institute of Standards and Technology (NIST) and the linear retention indices (LRI). Semi-quantification was performed by GC-FID. Eighty-two volatile compounds were identified; from each 47 were present in Ocimum gratissimum, 25 in Eryngium foetidum, 46 in Acmella oleracea, 15 in Hibiscus sabdariffa, 12 in Hibiscus acetosella, 8 in Portulaca oleracea, 5 in Pereskia aculeata and 3 in Xanthosoma sagittifolium. Terpenes constituted the most dominant volatile class in Ocimum gratissimum and Acmella oleracea, while aldehydes were mainly found in Eryngium foetidum, Hibiscus acetosella and Hibiscus sabdariffa fresh leaves. Pereskia culeata, Portulaca oleracea, and Xanthosoma sagittifolium did not present a broad distribution of volatile compounds, but (E)-2-hexenal, a compound with strong antimicrobial activity, was the main volatile identified in these plants. Volatile compounds, especially present in Acmella oleracea, Ocimum gratissimum and Eryngium foetidum may improve food quality and, to some extent, might be used as substitutes of synthetic additives in food formulations.