On the kinetics of the autoxidation of fats

Abstract

The mechanism of fat autoxidation is elucidated from the rate data. All the data treated here and in an earlier publication follow the same basic rate equation, including the time function fit} empirically derived for heterogeneous oxidation. Metals and glass (the wall of the reaction vessel} are catalysts. Depending on the state of the catalyst, fit) = t 2 or fit} = t. When fit} = t, the kinetics are first-order as found for monolayer autoxidation, but in bulk phase they are complicated by a transient stage caused by the solubilization of 02 into the hydroperoxide micelles produced in the exponential {"autocatalytic") part of the oxidation. Certain additives, such as inhibitors, affect the catalyst and thereby fit). The kinetics, as determined by 02 consumption or by analysis of the remaining unreacted substrate, show the first oxidation step. It is unaffected by further chemical changes of the primary oxidation products, e.g., decomposition of hydroperoxides and trimerization in the autoxidation of 9,11-octadecadienoic acid methyl ester.Autoxidation and rancidity of fats have been the subject of research for more than 100 years. Browne (1) in 1925 said "A good review of the literature before 1890 is given by Ritsert" (2). Reviews of more recent work are given by Richardson and Korycka-Dahl (3), Allen and Hamilton (4) and Frankel (5). The kinetics have been reviewed by Labuza H2Oad s --* Had s + OHad s [4]

Thermal Analysis of Autoxidation of Ethyl Esters of n-3 and n-6 Fatty Acids.

“…The kinetics of autoxidation have usually been considered for the individual steps (Labuza, 1971;Brimberg, 1993;Simic et a/., 1992). …”

Autoxidation of Mono-, Di-, and Trilinoleoyl Glycerols at Different Concentrations

“…Because this process usually includes initiation, propagation, and termination steps, its kinetics has also been studied for each step. 2,3) Ö zilgen and Ö zilgen 4) reported that the autocatalytic-type expression, a very simple equation, well describes the entire oxidation process of lipids. We also showed that the expression is applicable to the oxidation processes of fatty acids and their alkyl and glycerol esters.…”

On the kinetics of the autoxidation of fats: influence of pro‐oxidants, antioxidants and synergists

“…The kinetics of oxidation of different fatty acid substrates, treated in four preceding papers [5][6][7][8], seem to follow the same basic mechanism(s) emphasizing the importance of aspects related to heterogeneous oxidation [9][10][11]. Autoxidation is characterized by three kinetic stages with defined time ranges: the induction period, the autoxidation stage, and the last stage with constant rate of oxygen absorption [5][6][7][8].…”