The 2‐thiobarbituric acid reagent for determination of oxidative rancidity in fish oils

Abstract

Abstract A method has been devised for the quantitative determination of malonaldehyde in oxidized fish oils by means of the 2‐thiobarbituric acid reagent in alcoholic solution. TBA numbers and peroxide values have been determined at intervals during hydroperoxidation of pilchard oil. The curves follow the same general pattern but the numerical relationship between them depends upon the temperature of oxidation. In alcoholic solution, the reaction between thiobarbituric acid and malonaldehyde is carried out in the dark, because sunlight causes a decrease in optical density of the TBA‐malonaldehyde complex at 532 mॖ with the appearance of a second maximum at 452 mॖ. The nature of the compounds responsible for absorption at these two wave‐lengths is discussed.