Effect of light exposure on the quality of extra virgin olive oils according to their chemical composition

- The effects of market storage conditions on EVOO quality were simulated.
- Long light exposure times and chemical differences of the market products were considered.
- Commercial EVOO merchandise quality can be monitored by the K270 extinction coefficient.
- The trend of quality loss of an EVOO that is exposed to a light source depends strongly on its antioxidant heritage.
- Oleuropein derivatives are the most efficient antioxidants in terms of contrasting photooxidation.

The influence of light exposure on the quality of commercially available extra-virgin olive oils (EVOOs) of different chemical composition was studied as a function of storage (11 weeks) under conditions simulating market storage. By mildly stripping the polyphenols from oil 'A', with high levels of polyphenols and oleic acid, and oil 'B', exhibiting a medium level of polyphenols and a low level of oleic acid, 'C' and 'D' EVOOs were obtained. Ten EVOOs were produced as mixtures of these four oils. The initial concentrations of oleic acid and polyphenols in the 14 oils ranged from 64.5 to 77.7% and 18.1 to 1476.7 mg/kg, respectively. The extinction coefficient K270 well reflected the EVOO product quality. EVOOs richer in oleuropein derivatives showed superior oxidative stability, which resulted in lower off-flavour volatile compound production and α-tocopherol and polyphenols losses, and thus, higher EVOO sensory and health benefits.