Preservation of sensory attribute and chemical stability in extra virgin olive oil added with four Argentinean oregano essential oil as natural antioxidant

ASENSIO C.; OLMEDO R.H.; NEPOTE V.; GROSSO, N. R.

Las Vegas, USA

Congreso; Annual Meeting IFT - 2012; 2012

Virgin olive oil is consumed for its taste, aroma and nutritional properties. These properties should be protected during its shelf-life. Oregano essential oil has shown antioxidant activity that could preserve olive oil properties. The objective of this study was to evaluate the antioxidant effect of Argentinean oregano essential oils on extra virgin olive oil measuring sensory and chemical parameters. Essential oils (EO) from four different species of oregano: Mendocino (Men), Compacto (Com), Cordobes (Cor) and Criollo (Crio) were added at 0.05% w/w to extra virgin olive oil (OO). Control samples without essential oil were also prepared. Samples were stored at 23ºC during 126 days at light exposure (L) and darkness (D). EO composition was determined by CG-MS. Intensity ratings of sensory attributes were measured by descriptive analysis. Peroxide value (PV), conjugate dienes (CD), carotenoid and chlorophyll contents and free fatty acids (FFA) were measured as chemical oxidation indicators. Statistical analyses were performed: ANOVA, LSD test, correlation, regression and PCA. Intensity ratings of OO positive attributes decreased during storage while lipid oxidation indicators increased. Significant differences were observed between treatments. At storage day 126, OO-Control light exposure treatment had the highest PV 54.54 (meq0/kg), lowest fruity intensity 3.6 (in 10cm line scale) and chlorophyll content 1.47 (mg/kg) whereas Cor-D had the lowest PV 18.71 (meqO/kg) and the highest fruity (4.2 ) and chlorophyll (2.91 mg/kg) values. The two principal components explained the 72.7% variability in PCA. Rancid flavor and chemical indicators of lipid oxidation were located on the right side of PC1whereas positive attributes and chlorophyll and carotenoid content on the left side. The oregano EO, especially those with high amounts of thymol (Cor and Crio) exhibited higher antioxidant effect. The addition of oregano essential oils to extra virgin olive oil increases its self-life preserving the sensory and chemical quality parameter Extra virgin olive oil is highly appreciated for its health benefits, taste and aroma. These properties are an important aspect in this product quality and need to be preserved. The addition of natural additives instead of synthetic ones covers the present trend in food technology. This research showed that the addition of oregano essential oil preserved the intensity ratings of positive attributes in extra virgin olive oil during storage. The essential oil of the oregano variety called Cordobes exhibited better protecting effect on sensory properties of olive oil than the other oregano varieties. The addition of oregano essential oil should be considered for the food industry as a natural source of antioxidant additive for preserving sensory properties in extra virgin olive oil and other similar food products.