Lipid stability measurements oxidation techniques

The oxidative stability of food lipids has been evaluated by a variety of methods using a wide range of conditions and techniques for measuring oxidation. The choice of appropriate methods and oxidation conditions is critical in the interpretation of stability data. Thus, interpretation of data pertaining to lipid oxidations should take into account the limitation of the methodology used. The oxidative stability of unsaturated lipids can be estimated by determining the extent of oxidation produced under various defined and standardized conditions. The susceptibility of the samples to oxidation can be measured reliably if the samples are initially fresh (with a peroxide value approaching 0) and the conditions of oxidation are sufficiently mild and... 

Optimization of the oxidative stability of stressed foods requires examination of processing techniques and parameters to identify desirable changes. It is also necessary to review some of the often unrecognized negative changes in properties of processed foods that are the result of oxidation of lipids and proteins, pigments and flavor components induced by process conditions. In addition, measures should be taken to offset the adverse process influences. 

Lipid oxidation is an exothermic phenomenon that can be followed, at least at elevated temperatures, by DSC or (preferably) by isothermal calorimetry [41-44], Measurements can be performed under a static air atmosphere or, better, under oxygen flow or oxygen pressure. In the isothermal mode, induction times can be defined according to published procedures using other techniques (see Fig. 4). Figure 5 compares the oxidative stability at 130°C of three very different oils (safflower, blackcurrant seed, and Nujol). Induction time values can be used... 

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