Stability values obtained by different rapid methods as a means of evaluating antioxidants for fats and oils

Summary

ACOMPARISON was made of stability values and protection factors as determined by three widely used rapid methods—the active-oxygen, oxygen-absorption, and the oven-test methods. In most instances there was fair agreement between the results by the active-oxygen and oxygen-absorption methods, as indicated by protection factors. In general, use of dry air instead of moist air in the active-oxygen method resulted in little significant difference in the stability values although in some preparations, differences were found that may be significant. Use of dry oxygen in the active-oxygen method gave results comparable with those obtained by the oxygen-absorption method. In experiments in which an oven test was also used, the protection factors in most cases were in general agreement with those obtained by the other two methods.

The synergistic antioxidant effect of acidic compounds with phenolic antioxidants was most pronounced when lard of low stability was used. Likewise, the protection factors were disproportionately greater when antioxidants were added to lard of low stability than when added to lard of good stability. The results indicate that comparison of antioxidants by means of protection factors is valid only when the same substrate is used. Protection factors so obtained help to evaluate the order of effectiveness of various antioxidants but do not yield a strict quantitative comparison of the protective power of the antioxidants when applied to other substrates.