Antioxidant Activity of Methyl Caffeate‐Enriched Olive Oils: From Extra Virgin Olive Oil to Extra Virgin Olive Oil‐Based Microemulsions

Oxidative rancidity isthe main cause of extra virgin olive oil's (EVOO) quality deterioration. Here, methyl caffeate (CAME) is examined for possibly enhancing EVOO antioxidant activity. To improve CAME's solubility and efficacy, an EVOO-based water in oil microemulsion is used. The oxidative stability of EVOO is monitored. The antioxidant activity of EVOO is assessed both by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging and electron paramagnetic resonance (EPR) spectroscopy. Microemulsions' antioxidant activity is also determined by EPR spectroscopy. CAME's presence is found to increasethe oxidative stability, the antioxidant capacity, and the total phenolic content of the samples. The increase is dose-dependent according to the added ester amount. The use of EVOO-based microemulsions increases the ester's solubility rendering sonication unnecessary. The ester also improves the microemulsions' oxidative stability. Practical applications: The CAME enhancement of EVOO's antioxidant capacity can find direct application for improving the quality of oils with less nutritional value. The EVOO-based microemulsions can serve as functional oleaginous ingredients and delivery vehicles in several applications such as cosmetics, pharmaceuticals, and foods. The beneficial compounds of EVOO, combined with the chosen encapsulated substance, can be a powerful ingredient, of a chosen functionality.