CARBONYLS IN OXIDIZING FAT .12. ISOLATION OF FREE ALDEHYDES FROM AUTOXIDIZED TRIOLEIN TRILINOLEIN AND TRILINOLENIN

Methods of aldehyde isolation have been com-pared in the separation of free aldehydes from autoxidizing triglycerides of pure unsaturated fatty acids. Vacuum distillation was the mildest method of aldehyde isolation. Amounts of decomposed monocarbonyl precursors were directly related to acidity of extraction conditions. Analysis of autoxidizing trilinolenin showed, after attainment of an early maximum, a decrease in monocarbonyl values from vacuum distillation and Girard T reagent methods. Known aldehydes isolated by the acid celite methods increased progressively. These results were considered to be due to a decline in monomeric hydroperoxides as related to free aldehydes, and decomposition of not only monomeric peroxides but also polymers by the acid celite methods. Amounts of decomposed monocarbonyl precursors (broken down) were directly related to acidity of extraction conditions. Analysis of autoxidizing trilinolenin showed a decrease in monocarbonyl values from vacuum distillation and Girard T reagent values and an increase in these values with (those of) the acid celite reaction methods. This was considered to be due to a decline in monomeric hydroperoxides and decomposition of polymers by the acid celite methods. Studies with autoxidizing lard demonstrated several factors having a strong influence on the amount of aldehydes isolated by the phosphoric acid celite reaction method. Passage through the column decreased hydroperoxide values 10-15%. Amount of monocarbonyl compounds was directly related to the time of exposure on the column. The yield of aldehydes decreased with increase in the amount of oxidized material applied to the 2,4-dinitrophenylhydrazine reaction column. © 1968 American Oil Chemists' Society.