Degradation of monocarbonyls from autoxidizing lipids

Abstract

AbstractsIn an attempt to account for carbonyls found in oxidized lipid systems, but not theoretically predicted from the decomposition of lipid hydroperoxides, a member from each of the monocarbonyl classes commonly observed in oxidizing lipids was oxidized at 45C in a Warburg apparatus and the carbonyl products studied. The carbonyl compounds used weren‐nonanal,n‐non‐2‐enal,n‐hepta‐2,4‐dienal andn‐oct‐1‐en‐3‐one. Nonanal was relatively stable to oxidation and was oxidized to nonanoic acid. Oct‐1‐en‐3‐one did not absorb oxygen during a 52‐hr period; however, the unsaturated aldehydes oxidized at faster rates than methyl linoleate or linolenate. Non‐2‐enal upon absorption of 0.5 mole of oxygen was oxidized almost quantitatively to non‐2‐enoic acid. Hepta‐2,4‐dienal was polymerized at 0.5 mole of oxygen uptake. In addition both of the unsaturated aldehydes produced shorter chain mono‐ and dicarbonyls as oxidative degradation products. The identification of these compounds helps to explain the presence of carbonyls in oxidizing lipids and model systems that are not accountable through the decomposition of theoretically predictable isomeric hydroperoxide esters. The relatively large yield of malonaldehyde from the oxidized dienal suggests that these carbonyls may serve as a major source of malonaldehyde in oxidizing diene esters. Significant quantities of malonaldehyde are not observed in methyl linoleate until late stages of oxidation, and the dienals formed through degradation of primary hydroperoxides may in turn oxidize to give malonaldehyde.

Character impact odorants of boiled chicken: changes during refrigerated storage and reheating

“…14/15) during refrigerated storage of boiled chicken can be explained on the basis of model experiments performed by Lillard and Day [57] and Schieberle and Grosch [58]. These authors showed that unsaturated aldehydes are more sensitive towards autoxidation compared with the saturated ones.…”

Oxidative pathways to the formation of off-flavours

“…For example, from autoxidation of pure 2,4-decadienal at room temperature, a complex mixture of volatile products such as butenal, hexanal, 2-heptenal, 2-octenal, benzaldehyde, glyoxal, trans-2-buten-l,4-dial, furan, ethanol, acrolein, pentane, benzene, and acetic, hexanoic, 2-octenoic and 2,4-decadienoic acids have been identified by Matthews et al (1971). The oxidation of 2-nonenal at 45°C produces C2, C3, C7, C8 alkanals, glyoxal, and a mixture ofC7, C8 and C9 (X-keto aldehydes (Lillard and Day, 1964).…”

Aplicação do delineamento simplex-centroide no estudo da cinética da oxidação de biodiesel B100 em mistura com antioxidantes sintéticos

“…34 Por fim, temse a terminação que corresponde à formação de produtos estáveis, produtos secundários de oxidação, obtidos por cisão, e rearranjos dos peróxidos como epóxidos, compostos voláteis e não voláteis. 14,34,35 A Tabela 2 mostra o período em que foi observado o maior índice de peróxido para cada uma das amostras, incluindo o controle. Os tratamentos 3, 5, 6 e 7, os quais continham TBHQ, foram os que apresentaram maior tempo para atingir o índice de peróxido máximo, com destaque para a mistura binária BHT e TBHQ (tratamento 6) que apresentou atividade antioxidante por 16 dias a mais.…”