Effect of Extraction Method on Organoleptic, Physicochemical Properties and Some Biological Activities of Olive Oil from the Algerian Chemlal Variety

Abstract

Objective: The production of olive oil in Algeria is of great importance. The choice of the extraction method is crucial in order to achieve the best yields of high quality oil. This work aims to study the effect of the extraction method on the sensory and physicochemical characteristics and the antioxidant and antimicrobial activities of three types of olive oil derived from the same sample of olive fruits (Chemlal variety). Materials and Methods: Several physicochemical and sensory parameters of olive oil samples were evaluated by referenced methods (ISO, IOC, AFNOR, etc.). The fatty acid composition of oils was determined by gas chromatography. Total phenolic content and antioxidant activity were estimated using the Folin-Ciocalteu assay and FRAP test, respectively. Antimicrobial activity analysis was performed using the agar diffusion technique against five strains. Results: The analyses revealed that olive oil obtained by manual extraction is classified in the extra virgin category, according to the International Olive Oil Council. The two other oils, traditional and industrial, were of virgin class. Fatty acid composition shows significant differences between the three oils which are characterized by a remarkable richness of phenolic compounds (447-528 mg GAE/kg oil). The best antioxidant activity was noted in the manual olive oil (PR0.5=78.60 μg/mL). Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538 were more sensitive to action of the manual oil compared to other bacterial and fungal strains tested, with inhibition zones of 15.84±0.07 and 15.31±0.20 mm, respectively. This activity was significantly decreased by evaluating antimicrobial effect of the other oils. Conclusion: The method of extraction significantly affects the properties of olive oil, where the manual method preserves the best quality of oil.