On the flavour volatiles of fats and fat‐containing foods. I.—Degradation of the peroxides of autoxidised sunflower and linseed oils

Refined sunflower and linseed oils purified by ‘stripping’ in a molecular still, treatment with silicic acid and steam deodorisation were autoxidised at 37° to an oxygen absorption of approximately 100 μmoles/g. The amounts of peroxide, non‐volatile carbonyl and volatile carbonyl were determined in the oxidised oils before and after destruction of the peroxides by heating in vacuum. The peroxides (mainly linolenate) of the linseed oil decomposed more readily than those (mainly linoleate) of the sunflower oil, and produced a higher proportion (60% as compared with 40%) of carbonylic compounds. In both oils nearly half of the total carbonyl groups formed were in volatile compounds. Not more than 1–2% of the volatile carbonyls could have been formed from non‐peroxidic precursors.