The antioxidant properties of ethoxyquin and of some of its oxidation products in fish oil and meal

Ethoxyquin is an effective antioxidant for both fish oil and fish meal but its antioxidant activity often follows an initial burst of pro‐oxidant activity. Some oxidation products of ethoxyquin are shown to be powerful antioxidants as determined from measurements by the Warburg manometric technique. Of the compounds examined, 2,6‐dihydro‐2,2,4‐trimethyl‐6‐quinone imine and ethoxyquin nitroxide showed marked antioxidant activity.