Screening of Chemical Composition, Antimicrobial and Antioxidant Activities of Essential Oil and Volatile Fraction from Olive Mill Wastewater

Abstract

Oil mill wastewater is the main by-product of the olive oil industry resulting mainly from the treatment and pressing of olives in mills. It is a rich source of nutrients and phytochemicals with a wide spectrum of biological properties. The present study focuses on the chemical analysis and evaluation of the antimicrobial and antioxidant activity of the essential oil (EO) and the volatile fraction (VF) obtained, respectively, by hydrodistillation. Chemical analysis by gas chromatography coupled to mass spectrometry (GC/MS) and a flame ionisation detector (GC/FID) revealed the predominance of phenolic compounds (25.71%, 60.36%) and fatty acids (62.37%, 38.25%) for the VF and EO, respectively. It was also shown that the main compounds were oleic acid (24.9%) for the VF and 4-ethylphenol (28.5%) for the EO. The results of the antimicrobial activity in terms of MIC values against twelve microorganisms showed that, overall, the VF was more active than the EO. The antioxidant activity of the VF and EO was evaluated using the DPPH assay and expressed as half-maximal inhibitory concentration (IC50), where the EO (218 μg/mL) showed better antioxidant activity than the VF (244 μg/mL). The results also revealed that the antimicrobial activity and antioxidant activity values for both oils were significantly lower than the standards used.

From antiquity to contemporary times: how olive oil by-products and waste water can contribute to health

“…The increased phenolic levels or other ingredients present in the mixture, such as fatty acids, may be the cause of the enhanced antibacterial properties ( 52 ).…”

“…The OMWW extract has positive effects on normal cell lines, both in vitro and in vivo, which are summarized in the table. The increased phenolic levels or other ingredients present in the mixture, such as fatty acids, may be the cause of the enhanced antibacterial properties (52).…”

Antimicrobial Activities of Olive Oil Mill Wastewater Extracts against Selected Microorganisms

“…The mixture of the extract of ethyl acetate and OOMW phase gave relatively higher antimicrobial activities (Table 1) and were generally more effective against S. uberis, E. faecalis, B. spizizenii and B. cereus strains (p = 0.004), with 18.0 ± 1.8 mm, 18.8 ± 3.2 mm, 16.5 ± 0.6 mm, and 16.8 ± 1.0 mm inhibition zones, respectively. The higher antimicrobial activities could be due to the higher phenolic contents or other components, such as fatty acids, found in the mixture [50].…”