ABSTRACT: In the present study, the probability of packaged olive oil not reaching the end of its shelf life, P safe , was used as a quality factor to evaluate the time taken for olive oils stored at various conditions to reach the end of their shelf lives. P safe was used to comment on the activation energy required during the degradation process per actual or simulated case, and hexanal was used as the main quality-related indicator. Based on the month after bottling at which P safe reached 70%, the activation energy of an “equivalent” chemical reaction, representative of overall quality degradation, was calculated for several storage conditions. Using the differences between activation energies es- timated using the above method, we found the most important factors influencing the shelf life of the packaged olive oil to be the initial storage period in the dark, the role of elevated temper- atures, and the presence of light, either continuous or in alternat- ing patterns, in association with the packaging materials used in this study. These results were in qualitative agreement with previ- ously reported experimental observations and simulations, indi- cating the validity of using P safe , and of activation energies calcu- lated from it, to predict the shelf life of packaged olive oil. Paper no. J10976 in JAOCS 82, 119–123 (February 2005). KEY WORDS: Activation energy, flavors, olive oil, oxidation, packaging, shelf-life prediction. The type of material (plastics, glass, tin), the storage conditions (light, temperature), and the storage period can significantly in- fluence the quality of olive oil (1–5). Plastic bottles are used extensively for packing and bottling vegetable oils, but they are not always suitable for this purpose (6). Kiritsakis and Dugan (7) studied the relative effects of plastic and glass bottles on the oxidation of olive oil exposed to diffused light. They demon- strated the role of light and oxygen on the quality of the olive oil through the evolution of the PV. They also found that olive oil stored in colorless glass bottles and exposed to diffused light lost all of the chlorophyll and about 70% of the carotene con- tent. Another key parameter is the oxygen permeability of the container, since olive oil kept in bottles permeable to air (e.g., polyethylene and polypropylene) should be sold within 4 wk (8–10). Poly(vinyl chloride) (PVC) bottles with lower air per- meability can hold olive oil for 3 mon. The importance of monitoring temperature during oil pro- cessing, distribution, and storage becomes evident by recogniz- ing the effect of temperature abuse, which may result in a signif- icant reduction of the shelf life. The time for a food product to reach the end of its shelf life (response time) could be established for a range of temperatures under isothermal conditions. These data could be applied to the Arrhenius equation, and the activa- tion energy of the product could be determined. Among others, the activation energy approach was implemented previously to study the role of temperature on the kinetics of the spoilage process, e.g., to evaluate the application of an enzyme process- based time–temperature integrator (11) in the reduction of the L- ascorbic acid of green vegetables in the temperature range of freezing storage (12), or for the degradation of antioxidants and antioxidant activity in tomato products (pulp, puree, and paste) submitted to accelerated aging (13). Among the applications used to monitor the quality of olive oil based on the reaction kinetics during storage were kinetic studies of the thermodegradation reaction of the oils conducted by Paz and Molero (14,15). Their results showed that the oxidizing atmosphere has a negative influence on the thermal stability of the oils. This work suggested that con- sumable vegetable oils could be characterized not only by their thermogravimetrical curves but also by the kinetic data deduced. The influence of a series of metals (iron, copper, tin, and lead) on the thermal stability of olive oils of different ori- gins and refined grades was studied, and the influence of iron and tin on oil oxidation, compared with copper and lead, was demonstrated (16). Changes in the degradation rate also were compared with degradation in the absence of metals, confirm- ing the negative influence of iron and tin on the oil oxidation process, regardless of the kind of oil tested. Furthermore, the pheophytin-A photodecomposition process, at 15, 40, and 50°C and at three different luminous energies, was developed according to a first-order reaction (16). From the Arrhenius straight lines, it appeared that the incident luminous energy did not change the activation energy but increased the reac- tion frequency factor. Having recognized that data on the oxidative degradation ki- netics in packaged olive oil are scarce, in the present work we applied the activation energy concept to extra virgin olive oil packaged in various packaging materials and stored under a wide range of storage conditions. A better understanding of the syner- gistic effects among oxidation-favoring parameters during stor- age would allow a valuable quality-predicting methodology to be introduced for packaged olive oil. Copyright © 2005 by AOCS Press 119 JAOCS, Vol. 82, no. 2 (2005) *To whom correspondence should be addressed. E-mail: frank@ipta.demokritos.gr Use of the Activation Energy Concept to Estimate The Quality Reduction of Packaged Olive Oil Frank Coutelieris a, * and Antonis Kanavouras b a National Center for Scientific Research “Demokritos,” 15310 Aghia Paraskevi Attikis, Greece, and b Unilever Europe, Spreads and Cooking Products Category, Nassaukade 3, 3071 JL, Rotterdam, The Netherlands