Effect of light intensity on the photo-oxidation stability of red and yellow palm olein mixture

Abstract

Palm oil is an edible oil derived from the mesocarp of oil palm fruit (Elaeis guineensis), which has a high content of carotenoids and tocopherol components. This research aimed to study the effects of light intensity on the photo-oxidation stability of a red and yellow palm olein mixture. The red and yellow palm oleins were mixed into 100, 200, and 350 ppm carotene content. The photo-oxidation stability of the palm olein mixture was investigated under fluorescent light intensities of 5,000 and 10,000 lux at 31 ±2 °C for 7 days. Changes in the content of chlorophyll, carotene, tocopherols, and peroxide value (PV) were evaluated daily. The results showed that an increase in carotene and tocopherol contents effectively improved the photo-oxidative stability of the palm olein mixture. Degradation of chlorophyll, tocopherols, and increased PV were proportional to light intensity during photo-oxidation. There were no significant changes in carotene content at 5,000 lux light intensity exposure. The degradation rates of chlorophyll and tocopherols can be described as first-order reaction kinetics. In contrast, the increase rate of PV can be described as a zero-order kinetics model with k-values of 6.6 x 10-2, 4.9 x 10-2, 3.7 x 10-2 mequiv.kg-1.h-1, and 8.3 x 10-2, 6.8 x 10-2, and 5.6 x 10-2 mequiv.kg-1.h-1 in palm olein mixture, which contains 100, 200, and 350 ppm carotene at 5,000 and 10,000 lux light intensity exposure, respectively. These results suggested that carotene protected tocopherol in palm olein and that tocopherol and carotene synergistically acted as singlet oxygen quenchers during photo-oxidation.