Subject: Food Technology
Peanut oil is widely used in food but is susceptible to oxidation. This study investigated the antioxidant stability of high oleic (HO: 78.85 g/100 g oleic acid) and regular (C: 43.85 g/100 g oleic acid) peanut oils with oregano essential oil (OEO) added as a natural antioxidant. OEO contained γ-terpinene (25.71%), carvacrol (16.73%) and terpinen-4-ol (16.17%) as the principal compounds. Thermal processing (60 °C for 28 days) of OEO increased the carvacrol and o-cymene contents and decreased the terpinen-4-ol, linalool and γ-terpinene levels. Thus, carvacrol was the major compound with high oxidative stability. Thermal processing of the peanut oils showed that HO peanut oil developed less oxidation than C peanut oil. OEO provided antioxidant activity, which increased as its concentration increased (at 0.02 and 0.10% p/p of OEO, the peroxide value decreased by 18 and 46%, respectively). OEO displayed 54.7% free radical scavenging activity and 9.2 mg/g total phenolic content, explaining its antioxidant activity. Sensory analysis showed that OEO was detected in all samples, but consumer acceptance was greater when OEO was present (hedonic values of 7.4 and 6.8 for OEO at 0.02 and 0.10 g/100 g, respectively) compared to the peanut oil only control (hedonic value of 6.0).