Asian Journal of Current Research

Repeated heating of edible oils during frying accelerates lipid oxidation, resulting in the formation of degradation products that adversely affect nutritional quality and may pose health risks. This study compared the oxidative stability of three edible oils commonly consumed in India - mustard oil, groundnut oil, and coconut oil - under repeated heating conditions designed to simulate typical household frying practices. Changes in physicochemical properties, including pH, refractive index, free fatty acid content, acid value, peroxide value, iodine value, UV-visible spectroscopic oxidation indices, smoke point, and Fourier transform infrared (FTIR) spectral characteristics, were systematically analysed over successive heating cycles. The results revealed progressive oxidative deterioration in all three oils, with differences in thermal stability among them. Coconut oil exhibited the greatest oxidative stability, showing comparatively smaller changes in peroxide value, acid value, iodine value, and secondary oxidation products throughout the heating period. In contrast, mustard oil and groundnut oil, which contain higher proportions of unsaturated fatty acids, demonstrated greater susceptibility to thermal oxidation, as evidenced by marked increases in free fatty acid content, peroxide value, acid value, and spectroscopic oxidation markers. These findings highlight the influence of fatty acid composition on the thermal stability of edible oils. The study provides experimental evidence relevant to the selection of oils with greater resistance to oxidative degradation during repeated household frying. The findings contribute to food-quality assessment, consumer awareness, and safer cooking practices.