Physical and chemical behaviour of Nabali Mohassan single-cultivar olive oil during prolonged storage.

Abstract

The effect of storage time on the fluorescence emission intensity and physico-chemical properties of olive oil from the Palestinian cultivar Nabali Mohassan was investigated. Olive oil samples stored up to 7years were obtained from different olive orchards in Palestine, where prolonged storage is still in use. As a result of oxidation, all fluorescent minor compounds (tocopherols, chlorophylls, pheophytins and phenolic compounds) of olive oil significantly decreased as the storage time increased, whereas viscosity increased (P<0.05). Until 1 year of storage, the physico-chemical properties of olive oil samples were within the limits of both Palestinian and European quality standards, and minor compounds, although affected by a marked decrease compared to freshly produced oil, were still detectable. After 5years, a 90% decrease of the fluorescence attributed to tocopherols occurred and, after 7years, phenolics reached a loss of 90%. The analysis of fluorescence, together with other physical measures, was demonstrated to be a useful tool for monitoring oil aging. This is the first report on fluorescent minor compounds of oils obtained from Nabali Mohassan olive cultivar. A better knowledge of this single-cultivar oil could enhance the adoption of the best practices by producers, improving the whole production chain. © 2018 Society of Chemical Industry.