Effect of Linoleic and Linolenic Acid Contents on the Oxidation Stability of Interesterified Fats under Rancimat Test Conditions.

Abstract

This study aimed to better understand the association between the amount of polyunsaturated fatty acids, namely, linoleic acid (LA) and linolenic acid (LNA), and the increases in the peroxide value that results from storing interesterified fats, which are used as sources of solid fats in edible oil and fat products, at high temperatures. Six interesterified fats with different LA and LNA contents were prepared and oxidized at 50°C, 60°C, 70°C, and 80°C under Rancimat test conditions. The oxidation rate increased with LA and LNA contents and increasing temperature. The oxidation kinetic analysis during the early oxidation stages demonstrated that when LA and LNA exceeded 8% and 2% respectively, the oxidative stability decreased as expected. However, the total LA and LNA contents had a higher correlation with the reaction rate constant [k (meq kg^-1 h^-1 )] than each amount of LA and LNA contained therein. In other words, the oxidation stability of the interesterified fats used in this study depended on the total LA and LNA contents.