Effect of carvacrol on oxidative stability of sunflower seed oil during storage

Natural antioxidants recently have gained popularity since synthetic ones have toxic and carcinogenic effects. In the present study, carvacrol was used as a natural antioxidant and compared with a synthetic antioxidant BHT. In this study, the shelf- life of oils was determined both under normal conditions and using accelerated tests. Rancimat and PetroOXY devices are used to investigate the oxidative stability and shelf-life of edible oils. Therefore, the purpose of this study was to predict shelf-life of mid-oleic sunflower seed oil by Rancimat and PetroOXY test devices. The study was performed at 110, 120, 130oC with both Rancimat and PetroOXY devices as accelerated methods. In addition, sunflower seed oil was stored at normal storage temperatures of 20, 30 and 40oC. It was determined that carvacrol was not as protective as BHT in both normal storage conditions and accelerated methods. The induction periods (IP) with Rancimat and PetroOXY devices were measured as 5.45, 2.86 and 1,45 and 2.23, 1.12 and 0.62 hours at temperatures of 110, 120 and 130oC, respectively. At normal storage temperatures, the IP values were measured by tangent method in terms of days. The peroxide values (PV) at the determined IP values were 12.08, 29.24 and 33.09 at 20, 30 and 40 oC, respectively. The induction periods predicted from Rancimat and PetroOXY devices for normal storage temperatures of 20, 30 and 40°C were 88.71, 48.85 and 23.22 and 30.17, 15.91 and 8.38 days, respectively. The shelf-life prediction for normal storage temperatures from Rancimat method was seems more reliable than those of PetroOXY device. Also, there was a good correlation between two accelerated methods and it was observed that PetroOXY was a faster method than Rancimat. Key Words: Rancimat, PetroOXY, Oxidation Stability, Induction Period, Storage