The experimentally defined oxidative alterations taking place in packaged olive oil stored in various packaging materials and storage conditions, were used as basic evidence in order to develop and support a descriptive mathematically expressed theory, and eventually to conclude on a predictive model. Hexanal was experimentally quantified for extra virgin olive oil packaged in 0.5 L glass, PET, and PVC bottles, and stored at 15 degrees C, 30 degrees C and 40 degrees C under fluorescent light or dark conditions for 12 months. A set of mass transport equations describing the chemical reactions occurring in the oil phase as well as the diffusion of oxygen in the oil phase and through the packaging material, was numerically solved for various combinations of temperatures, light conditions and packaging materials. In addition, the probability of the packaged olive oil not to reach the end of its shelf life during a certain time period, was estimated and proposed as a quality reduction indicator. The suggested model could be used as a tool for an accurate forecast of the quality issues for packaged olive oil. (c) 2005 Elsevier Ltd. All rights reserved.