Quality, stability and radical scavenging activity of olive oils after Chétoui olives (Olea europaea L.) storage under modified atmospheres.

At the industrial scale, the major source of olive oil deterioration is the poor handling of the raw material during the time separating harvesting from processing. The objective of this work was to verify the effect of modified atmospheres and cold storage in relation to quality parameters of the extracted oils. Olives (cv Chétoui) intended for oil extraction, were stored for 21 days at two different temperatures (ambient temperature 14 ± 2 °C and 5 °C) and under two different modified atmospheres 21% O₂ - 0% CO₂ and 2% O₂ - 5% CO₂. Oils quality was ascertained with analytical parameters: free fatty acids, peroxide value, K₂₃₂, K₂₇₀ as suggested by European regulation. Oxidative stability, total phenols content, radical scavenging activity and fatty acids composition were carried out in order to measure the hydrolytic and oxidative degradation of oils. Olive oils quality parameters were significantly affected by treatments with especially a beneficial effect on primary oxidation indicators and free acidity. Most efficient treatments, with regard to oils phenolic content and involved parameters, were 21% O₂ - 0% CO₂ at ambient temperature (636.25 mg ca/kg) and 2% O₂ - 5% CO₂ under 5 °C (637.50 mg ca/kg). Those two treatments improved individually oil samples phenolic content of 25% but not at the same storage period.