Oxidative Stability of Avocado and Peanut Oils Under Different Heating Temperatures

Abstract

The objective of this research was to investigate the effect of heating temperature on the quality parameters of avocado and peanut oils subjected to heating. Vegetable oils were heated at varying temperatures (110, 140, 170, 200 and 230�C for 30 min) to follow quality alterations. Levels of peroxide value, iodine value, thiobarbituric acid reactive substances, total polar compounds, refractive index, free acidity, and fatty acids composition were determined to measure the extent of lipid oxidation. Peroxide value was significantly (p [ 0.001) influenced by heating temperature in the case of peanut oil. Iodine value decreased significantly (p [ 0.01) in both oils with the increase in heating temperature due to the decrease of the unsaturation degree. Avocado oil showed the smallest increase in thiobarbituric acid reactive substances and total polar compounds during heat treatment. The fatty acids profile of peanut oil was rich in polyunsaturated fatty acids with a level of 42%, followed by monounsaturated fatty acids with about 36%. The heat treatment of oils has produced changes in unsaturated fatty acids, these have undergone isomerization from cis to trans form. The increases of heating temperature up to 230�C significantly deteriorated the quality of peanut oil, but to a lesser extent the one of avocado oil.