Changes in volatile compounds of virgin olive oil flavored with essential oils during thermal and photo-oxidation

Abstract

The effects of four essential oils from peppermint (Micromeria fruticosa), oregano (Origanum onites), thyme (Thymus vulgaris), and laurel (Laurus nobilis) on the volatile compounds of olive oil were determined. The concentration of essential oils was 0.05% (v/w) and flavored olive oil samples were stored for 45 days at 60 degrees C and room temperature for thermal oxidation and photo-oxidation under fluorescent light, respectively. Control and flavored olive oils were analyzed after 15, 30, and 45th days to track the changes in their volatile compound contents using HS-SPME/GC-MS technique. Higher concentrations of diversified volatile components were detected under thermal oxidation conditions rather than photo-oxidation. According to thermal oxidation results, the E-2-hexenal values of control and flavored oils with peppermint essential oil were higher at the end of 30 days storage, while flavoring with essential oil of Thymus vulgaris resulted in the highest E-2-hexenal value for photo-oxidation. Results indicated that the main components of essential oil transferred into olive oil samples. Carvacrol was present in flavored oils with oregano and thyme. Eucalyptol and pulegone were determined as major components in flavored oils with laurel and peppermint essential oils, respectively. In both oxidation methods, these volatile components remained stable and little or no loss was observed.