The effect of rosemary essential oil on physico-chemical properties of extra-virgin olive oil stored in colourful bottles

The aim of the study was to investigate the effect of both storage material colour (red, green, yellow and transparent glass bottle) and rosemary essential oil on the physico-chemical properties of extra-virgin olive oil. For this reason, free fatty acid, peroxide value, viscosity, colour and fatty acid composition of oils were measured at regular intervals. Free fatty acid and peroxide values of olive oils stored in different coloured bottles increased partly during storage. After 90 days of storage, free fatty acid values of samples changed between 0.78 and 0.89 mg KOH/g oil. By the 90th day of storage peroxide values of samples had changed from 32.75 to 79.46 meq O2/kg oil, whereas the peroxide value of the control group on the 90th day was 94.55 meq O2/kg. On the first day (0 day), 'L*', 'a*' and 'b*' values of control groups were determined to be 70.81, -3.69 and 38.26, respectively. During storage, these values partly increased. Linoleic acid (40.95-43.92%), oleic acid (33.04-34.99%) and palmitic acid (12.38-13.58%) were the major fatty acids of olive oils. In view of the analysis, the best results were obtained from oil stored in a green bottle. The addition of rosemary essential oil reduced lipid oxidation and showed an antioxidant effect when compared with the control group.