Lipid Oxidation: Measurement Methods

Abstract

Numerous analytical methods are routinely used for measuring lipid oxidation in foods. However, there is no uniform and standard method for detecting all oxidative changes in all food systems. Therefore, it is necessary to select a proper and adequate method for a particular application. The available methods to monitor lipid oxidation in foods can be classified into five groups based on what they measure: the absorption of oxygen, the loss of initial substrates, the formation of free radicals, and the formation of primary and secondary oxidation products. A number of physical and chemical tests, including instrumental analyses, have been employed in laboratories and the industry for measurement of various lipid oxidation parameters. These include the weight‐gain and headspace oxygen uptake method for oxygen absorption: chromatographic analysis for changes in reactants; iodometric titration, ferric ion complexes, and Fourier transform infrared (FTIR) method for peroxide value; spectrometry for conjugated dienes and trienes, 2‐thio‐barbituric acid (TBA) value, p ‐anisidine value ( p ‐AnV), and carbonyl value; Rancimat and Oxidative Stability Instrument method for oil stability index; and electron spin resonance (ESR) spectrometric assay for free‐radical type and concentration. Other techniques based on different principles, such as differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR), have also been used for measuring lipid oxidation. In addition, sensory tests provide subjective or objective evaluation of oxidative deterioration, depending on certain details.

Oxidative Stability of Lipid Fraction of Cookies Enriched with Chokeberry Polyphenols Extract

“…TOTOX values refl ect contents of both hydroperoxides and their breakdown products, and provide a better estimation of the progressive oxidative deterioration of fats e.g. during storage [Shahidi & Zhong, 2005;Mildner-Szkudlarz et al, 2009]. Exactly the same tendency as for AV was observed for TOTOX in the case of both margarine and butter cookies.…”

“…In butter cookies, only the content of 100 mg of CPE caused the inhibition of oxidative changes till the 12 th week of storage. The anisidine value (AV) is an indicator of the concentration of secondary lipid oxidation products generated during the decomposition of hydroperoxides [Shahidi & Zhong, 2005]. These unstable compounds were consequently broken down by a free radical mechanism to give hydroxyl free radical and lots of other compounds -alcohols, aldehydes, ketones a Values are expressed as means ± SD of 3 independent assays.…”

“…Many other substances may react with the TBA reagent and contribute to the increased absorption, causing an overestimation of the intensity of color complex. Interferences may come from additional absorption of other alkanals, 2-alkenals, 2,4-alkadienals, ketones, ketosteroids, acids, esters, proteins, sucrose, urea, pyridines and pyrimidines, also referred to as TBARS [Shahidi & Zhong, 2005]. Due to the non-specifi city of the TBARS test, its results refl ect the rancidity of food better than other conventional methods, especially in the case of off-fl avors which are caused by volatiles from lipids and are affected by products of lipids interaction with nitrogenous compounds [Kolakowska, 2003].…”

Impact of Extraction Method on Physicochemical Characteristics and Antioxidant Potential of <i>Adansonia digitata</i> Oil

“…Indeed, the oxidation of the oils leads to the formation of hydroperoxides, primary products of oxidation. Thus, the peroxide value corresponding to the hydroproxide content represents a very useful and very sensitive criterion for assessing the first stages of the oxidative deterioration of a fatty substance and an oil during production and storage [58] [59]. This standard method is included in the specifications for "fatty substances" with a threshold value of 10 meq O 2 per kg of material for a refined oil [58] [60].…”

Comparative analysis of phenolic contents and total antioxidant capacity of Moringa oleifera Lam

“…Phenolic antioxidants form a radical with low reactivity, due to delocalization of the unpaired electron over the aromatic ring, and exhibit no further potential to react with lipids after hydrogen abstraction. 5 Consumption of food items rich in antioxidant is recommended by several studies to augment array of free radical scavengers inside the body. To combat excess of free radicals, nutraceutical antioxidants as dietary supplements exerting positive pharmacological effects on specific human diseases must be explored.…”