Abstract

PHYTOCHEMICAL ANALYSES OF SUPERCRITICAL CO2 EXTRACT OF TUNISIAN PSIDIUM GUAVA SEEDS

S. Belghith Igueld*, C. Charbonnel, D. Barth, M. Trabelsi-Ayadi and J.K. Cherif

Abstract

This study aimed to determine the fatty acid profile and quantify the bioactive compounds present in tunisian guava seed powder (Psidium guajava L.). The research was conducted on the extracts obtained by supercritical fluid extraction (SFE) and compared with those obtained by maceration and soxhlet. The SFE with carbon dioxide (CO2) and ethanol as co-solvent was applied using two modes of extraction. The SFE(A) direct mode at 20MPa and 333K and the SFE(B) mode in six steps using a pressure and temperature variation (10, 20 MPa / 313, 323, 333K). The SFE give biphasic extracts, ethanolic and lipid fractions. The ethanolic fractions were subjected to the scavenging tests of DPPH and ABTS radicals. The total phenolics content and flavonoids were measured using standard methods and the lipid fractions were analyzed by GC-MS. In SFE the yield was highest at high pressure and temperature (333K/20MPa) (5.9%). The polyphenols and flavonoid contained in ethanolic fractions obtained by SFE (B) were respectively 2.57 mg GAE.g-1DM and 10, 19 mg EQ.g-1 DM. These values were twice higher than that obtained by the direct mode SFE (1.19 and 6.23). The lipid profile of oils showed a predominance of unsaturated fatty acids (86.6 to 88.78%), especially linoleic acid (ω6) and oleic acid (ω9). The extraction method showed rich sample in phenolics compounds and fatty acids. The SFE (B) was efficient, selective and gave various extracts with different chemical compositions depending on temperature and pressure variations.

Keywords: Psidium guava, Total phenolic, Flavonoïds, Antioxidant activity, Supercritical fluid extraction.