Mechanisms of Lipid Oxidative Processes and Their Inhibition

Abstract

A concise overview of the kinetics, energetics, and mechanisms of oxidative processes involving fatty acids in simple model systems relevant to autoxidation of foods is presented. Endogenous and exogenous factors that initiate oxidative processes in biochemical systems are reviewed and elements of and conditions for propaga tion of chain peroxidation processes are defined. Mechanistic aspects of chain-breaking antioxidants, including redox potentials, are presented. Biomarkers of fatty acid peroxidation are briefly reviewed and their relevance and specificity assessed.Food quality, excluding bacterial and enzymatic spoilage, deteriorates on standing due to oxidative processes induced and propagated by atmospheric oxygen (1). The appearance, texture, flavor, and odor of foods are affected by oxidative processes. The extent of these changes depends on the type of food and conditions. The rancidity of fats, which is unpleasant, can be reduced by storing fats at lower temperatures. Although low-temperature storage efficiently preserves saturated and lower unsaturated fats, reduced temperature alone is not sufficient to protect polyunsaturated fish oils against oxidation. For example, refrigeration of ham at 4 ° C preserves its quality for days or even weeks. On the other hand, refrigerated cooked mackerel is inedible after only two days.In addition to the undesirable sensory characteristics of autoxidized foods, questions have been raised regarding the safety of oxidation products in foods (2). Can hydroperoxides, epoxides, and their decomposition products (diverse carbonyl compounds) contribute to carcinogenesis through the stages of initiation, promotion, or progression? Hydroperoxides are known to damage DNA. Carbonyl compounds, although unreactive with DNA, may affect cellular signal transduction.Foods are complex systems with numerous components. Hence, oxidative mechanisms are often difficult, if not impossible, to study directly. The very short

Characterization of the Oxidation of Rapeseed and Butter Oil Triacylglycerols by Four Analytical Methods

“…Many review articles have been written recently on its mechanisms, kinetics and products (1)(2)(3)(4), as well as on controlling it (5,6). The amount of unsaturated acyls and their degree of unsaturation are the most important factors affecting oxidation (1,3,4,7).…”

“…The amount of unsaturated acyls and their degree of unsaturation are the most important factors affecting oxidation (1,3,4,7). Other factors controlling oxidizability are position of unsaturated acyls in the triacylglycerols (TAGs) (7)(8), and the presence and interference of anti-and pro-oxidants (1,2). Comparison of oxidation studies is very difficult because the experimental conditions affect which reaction routes take place, and the analytical methods determine which reactions and products are looked at.…”

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). …”

Kinetic Expression for the Oxidation of Linoleic and Arachidonic Acid Esters in Their Mixed System

“…[1][2][3] ÄOzilgen and ÄOzilgen 4) have reported that a kinetic expression of the autocatalytic type in terms of the fraction of the unoxidized substrate could describe the entire oxidation process of some lipids. We have also reported that the expression was applicable to the entire oxidation process of n-6 fatty acids, their methyl or ethyl esters 5) and their acylglycerols, 6) and to theˆrst half of the oxidation process of n-3 fatty acids, their esters 5) and their acylglycerols.…”