Lipid oxidation has been identified as a major deterioration process of vegetable oils, which leads to the production of primary and secondary oxidative compounds that are harmful to human health. Oleoresins of ginger, garlic, nutmeg, pepper, cloves, and cinnamon were extracted and incorporated into coconut oil, and change occurrence on physicochemical properties, thermal stability, shelf life, and antioxidant activity was monitored against the same properties of pure coconut oil. Lipid oxidation was assessed in terms of the free fatty acid level and peroxide value. For the comparison purpose, another oil sample was prepared by incorporating vitamin E too. Results revealed that both peroxide value and FFA of pure and flavored coconut oil samples after a one-week storage period were 3.989 ± 0.006 and 3.626 ± 0.002 mEq/kg and 0.646 ± 0.001 and 0.604 ± 0.002 (%), respectively. Saponification value, iodine value, smoke point, and the flashpoint of flavored oil were decreased while increasing the viscosity during storage. The highest phenolic content and DPPH free radical scavenging activity were found in flavored coconut oil. Since spices containing antioxidants, the thermal stability of flavored oil was better than that of pure coconut oil. Both oleoresins and vitamin E-incorporated samples showed the same pattern of increment of FFA and peroxide value during storage; however, those increments were slower than those of pure coconut oil.
Copyright © 2020 Dilini N. Perera et al.