Decrease of chemical and volatile oxidation indicators using oregano essential oil combined with BHT in sunflower oil under accelerated storage conditions

Abstract

This study compared the antioxidant properties of oregano essential oil (OEO) and butylated hydroxytoluene (BHT) alone and when combined. The principal components in OEO were gamma terpinene (25.1 g/100 g), terpinen-4-ol (16.7 g/100 g), and carvacrol (16.2 g/100 g). OEO showed 60% DPPH inhibition and 10 mg/g total phenolic compounds. The antioxidant capacity of OEO (0.02, 0.10, and 0.20 g/100 g) and BHT (0.01 and 0.02 g/100 g) and their combinations were tested in sunflower oil oven-heated at 60 °C, by measuring the chemical (peroxide value, p-anisidine value, and conjugated dienes) and volatile (hexanal, 2-heptanal, and 2,4-decadienal) indicators over 14 days. The combined samples (oregano essential oil and BHT) showed the greatest protection against lipid oxidation. On day 14, the peroxide value of the control (without added antioxidants), OEO (0.02 g/100 g), BHT (0.01 g/100 g), and OEO + BHT (0.02 + 0.01 g/100 g) treatments decreased in the order of 136.36, 102.68, 83.24, and 41.37 meqO2/kg, respectively, for example. In the consumer sensory test, samples containing OEO at 0.02 and 0.10 g/100 g attained greater acceptance scores (7.3 and 6.7, respectively, on a 9-point hedonic scale) as compared with the control (6.1). Discriminative duo–trio testing presented significant differences between all OEO-containing samples relative to the control. The synergistic antioxidant activity between OEO (termination-enhancing antioxidant) and BHT (chain-breaking antioxidant) demonstrates an alternative approach to impede lipid oxidation in foods, by decreasing the use of synthetic compounds in the food industry.