Efficacy of exogenous natural antioxidants in stability of polyunsaturated oils under frying temperature

The demand for plant source of polyunsaturated fatty acid (PUFA) is increasing due to the health concern over animal oils, but oxidation in PUFA-rich oils occurs rapidly during frying process. Under frying conditions, numerous reactions take place with the formation of degradative products which reduce nutritional quality and shelf-life of frying oil and fried foods. Using natural antioxidants instead of synthetic ones has been the tendency for retarding oil deterioration during frying. The chemical degradation of natural antioxidants during frying operation, seems to be the major pathway for antioxidant loss. This suggest to require a continuous modification to enhance their performances. In fact, much study was carried out on the activities of natural antioxidative agents at ambient or accelerated storage temperatures. The information on the fate of natural antioxidants at frying conditions is limited. Nevertheless, the need to develop a safe, potent, and stable natural antioxidative agent for frying operation still remains an appealing task. This review highlights the recent information on the performance of exogenous natural antioxidants in frying stability of polyunsaturated oils. The present investigations indicate that the stability is not just a function of individual components but may be a cumulative effect of various endogenous and exogenous antioxidants. Most of common antioxidants such as β-carotene, tocochromanols etc. may retard oxidative degradation during storage at lower temperature, they are less effective under frying conditions. Tocopherol, β-carotene and phenolic acids may form synergistic mixture. Under frying conditions, γ-oryzanol and phenolic compounds offer good protection of oils against oxidative deterioration.