Carbonyls in oxidizing fat. VII. A comparison of methods of isolating monocarbonyl compounds

Abstract

Comparison of quantitative methods for the isolation of aldehydes from lard oxidized at 23C showed an extreme sensitivity of precursors to isolation conditions. Differences existed in the quantity and class compositions of the monoearbonyl compounds isolated. Acid conditions caused considerable breakdown of alkanal and alk-2-enal precursors. Steam distillation (100C) released alkanals, alk-2-enals, and alk-2,4-dienals. The mild Girard T method apparently produced a small amt of alk-2-enals from precursors, but except in the initial stages isolated the lowest amounts of aldehydes. Complete evaluation of the method for isolation of free aldehydes was not possible because alkanals were released from precursors during the vacuum distillation procedure (50C). The Schwartz (dilute phosphoric acid), Girard T, and vacuum distillation methods isolated similar amounts of alk-2,4-dienals. Curious changes in relationships, possibly indicative of oxidation stages, were observed as autoxidation progressed.

Carbonyls in Oxidizing Fat. 11. The Effect of the Pro‐oxidant Activity of Sodium Chloride on Pork Tissue

“…Free volatile carbonyl compounds were isolated from 10 g samples by the vacuum distillation method of Lea et al (1962) as modified by Gaddis et al (1960) and Gaddis et al (1965). Th e volatile carbonyls were.…”

Spectrophotometric determination of saturated and alpha, beta‐unsaturated carbonyl in complex systems at a single wavelength

“…Gaddis et al (3,4) separated monoearbonyls as the DNPH from raneid fats with paper chromatographic procedures, followed by speetrophotometrie determination of the separate DNPH. More recently they describe the isolation of mono earbonyls by vae-400 uum distillation and testing with Girard T reagent.…”