Extra Virgin Olive Oil Stored in Different Conditions: Focus on Diglycerides

The effects of storage conditions of extra virgin olive oil (EVOO) on the isomerization of diglycerides (DGs) have been investigated. Aliquots of EVOO were stored for 14 months under four different conditions: at 20°C in darkness and in light, at 4-6°C in light and at 20°C in light with argon in the headspace. Samples were analysed bimonthly: 12 DGs with C34 and C36 (1,2 and 1,3 isomers) were tentatively identified and quantified by GC-FID. After 14 months, a clear tendency towards a decrease of 1,2-DGs and a significant increase of 1,3-DGs during storage was observed for all samples. 1,2-DGs were always predominant compared to 1,3-DGs and, for both types, C36 DGs were prevalent compared to C34 DGs. Overall, EVOO stored at 4-6°C in light showed the highest preservation of 1,2-DGs.