Lipid hydroperoxides are important factors in lipid oxidation due to their ability to decompose into free radicals. In oil-in-water emulsions, the physical location of lipid hydroperoxides could impact their ability to interact with prooxidants such as iron. Interfacial tension measurements show that linoleic acid, methyl linoleate, and trilinolein hydroperoxides are more surface-active than their non-peroxidized counterparts. In oil-in-water emulsion containing surfactant (Brij 76) micelles in the continuous phase, linoleic acid, methyl linoleate, and trilinolein hydroperoxides were solubilized out of the lipid droplets into the aqueous phase. Brij 76 solubilization of the different hydroperoxides was in the order of linoleic acid > trilinolein > or = methyl linoleate. Brij 76 micelles inhibited lipid oxidation of corn oil-in-water emulsions with greater inhibition of oxidation occurring in emulsions containing linoleic acid hydroperoxides. Surfactant solubilization of lipid hydroperoxides could be responsible for the ability of surfactant micelles to inhibit lipid oxidation in oil-in-water emulsions.
The paper discusses the levels of degradation of some co-and by-products of the food chain intended for feed uses. As the first part of a research project, Feeding Fats Safety, financed by the 6 th Framework Programme-EC, a total of 123 samples were collected from 10 European countries, corresponding to fat co-and by-products such as animal fats, fish oils, acid oils from refining, recycled cooking oils, etc. Several composition and degradation parameters (moisture, acid value, diacylglycerols and monoacylglycerols, peroxides, secondary oxidation products, polymers of triacylglycerols, fatty acid composition, tocopherols and tocotrienols) were evaluated. These findings lead to the conclusion that some fat by-and co-products, such as fish oils, lecithins and acid oils, show poor, non-standardized quality and that production processes need to be greatly improved. Conclusions are also put forward about the applicability and utility of each analytical parameter for characterization and quality control.
Bakery products such as biscuits, cookies, and pastries represent a good medium for iron fortification in food products, since they are consumed by a large proportion of the population at risk of developing iron deficiency anemia, mainly children. The drawback, however, is that iron fortification can promote oxidation. To assess the extent of this, palm oil added with heme iron and different antioxidants was used as a model for evaluating the oxidative stability of some bakery products, such as baked goods containing chocolate. The palm oil samples were heated at 220°C for 10 min to mimic the conditions found during a typical baking processing. The selected antioxidants were a free radical scavenger (tocopherol extract (TE), 0 and 500 mg/kg), an oxygen scavenger (ascorbyl palmitate (AP), 0 and 500 mg/kg), and a chelating agent (citric acid (CA), 0 and 300 mg/kg). These antioxidants were combined using a factorial design and were compared to a control sample, which was not supplemented with antioxidants. Primary (peroxide value and lipid hydroperoxide content) and secondary oxidation parameters (p‐anisidine value, p‐AnV) were monitored over a period of 200 days in storage at room temperature. The combination of AP and CA was the most effective treatment in delaying the onset of oxidation. TE was not effective in preventing oxidation. The p‐AnV did not increase during the storage period, indicating that this oxidation marker was not suitable for monitoring oxidation in this model.
We used an induced version of the FOX method to assess the oxidative stability of meats. Formerly, this induced version only measured the lipid hydroperoxide (LHP) value once the ferrous oxidationxylenol orange (FOX) reaction had reached a plateau. However, samples could have similar final LHP values that were reached in different ways. Thus, there may be variations in the samples' susceptibility to oxidation that are not detected by a final measurement of the LHP value. If the LHP value is measured at different points in the FOX reaction, it might be possible to calculate parameters such as induction time, oxidation rate, maximum LHP value, time of maximum LHP value and area under the curve. Such parameters might provide deeper insight into the evolution of oxidation in each sample than a final measurement of the LHP value. However, the accuracy of the measurement of these parameters could depend on the number of LHP measurements that can be taken during the FOX reaction. This improvement in the FOX method for assessing sample susceptibility to oxidation was applied to meats and other tissues such as liver.
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