AbstractThis paper deals with an evaluation of malic acid in a number of different lipids of animal and vegetable origin under comparable conditions. An Active Oxygen Method was used, with citric acid as the standard of comparison. In most cases, the performance of the acids was determined in the presence and absence of added iron salts and antioxidants butylated hydroxyanisole and butylated hydroxytoluene. Mathematical evaluation of the data shows malic acid to be at least as effective as citric acid in most cases. In very few instances, a reversal of performance was observed depending on experimental conditions used. In a few experiments, malic acid was also tested against phosphoric acid and found to be equal to or better than the latter. Phosphoric acid caused darkening of the oils at the test temperature used.