Effects of phospholipids on the antioxidant activity of α-tocopherol in the singlet oxygen oxidation of canola oil

Lipid oxidation in emulsions: New insights from the past two decades

Lipid oxidation constitutes the main source of degradation of lipid-rich foods, including food emulsions. The complexity of the reactions at play combined with the increased demand from consumers for less processed and more natural foods result in additional challenges in controlling this phenomenon. This review provides an overview of the insights acquired over the past two decades on the understanding of lipid oxidation in oil-in-water (O/W) emulsions. After introducing the general structure of O/W emulsions and the classical mechanisms of lipid oxidation, the contribution of less studied oxidation products and the spatiotemporal resolution of these reactions will be discussed. We then highlight the impact of emulsion formulation on the mechanisms, taking into consideration the new trends in terms of emulsifiers as well as their own sensitivity to oxidation. Finally, novel antioxidant strategies that have emerged to meet the recent consumer's demand will be detailed. In an era defined by the pursuit of healthier, more natural, and sustainable food choices, a comprehensive understanding of lipid oxidation in emulsions is not only an academic quest, but also a crucial step towards meeting the evolving expectations of consumers and ensuring the quality and stability of lipid-rich food products.

Physical and Oxidative Stability of Flaxseed Oil-in-Water Emulsions Fabricated from Sunflower Lecithins: Impact of Blending Lecithins with Different Phospholipid Profiles

There is great interest in the formulation of plant-based foods enriched with nutrients that promote health, such as polyunsaturated fatty acids. This study evaluated the impact of sunflower phospholipid type on the formation and stability of flaxseed oil-in-water emulsions. Two sunflower lecithins (Sunlipon 50 and 90) with different phosphatidylcholine (PC) levels (59 and 90%, respectively) were used in varying ratios to form emulsions. Emulsion droplet size, charge, appearance, microstructure, and oxidation were measured during storage at 55 °C in the dark. The physical and chemical stability increased as the PC content of the lecithin blends decreased. The oxidative stability of emulsions formulated using Sunlipon 50 was better than emulsions formulated using synthetic surfactants (SDS or Tween 20). The results are interpreted in terms of the impact of emulsifier type on the colloidal interactions between oil droplets and on the molecular interactions between pro-oxidants and oil droplet surfaces.

Effect of Extraction Method on the Oxidative Stability of Camelina Seed Oil Studied by Differential Scanning Calorimetry

Camelina seed is a new alternative omega-3 source attracting growing interest. However, it is susceptible to oxidation due to its high omega-3 content. The objective of this study was to improve the oxidative stability of the camelina seed oil at the extraction stage in order to eliminate or minimize the use of additive antioxidants. Camelina seed oil extracts were enriched in terms of natural antioxidants using ethanol-modified supercritical carbon dioxide (SC-CO₂ ) extraction. Oxidative stability of the camelina seed oils extracted by ethanol modified SC-CO₂ was studied by differential scanning calorimeter (DSC), and compared with cold press, hexane, and SC-CO₂ methods. Nonisothermal oxidation kinetics of the oils obtained by different extraction methods were studied by DSC at varying heating rates (2.5, 5, 10, and 15 °C/min). Increasing ethanol level in the ethanol-modified SC-CO₂ increased the oxidative stability. Based on oxidation onset temperatures (T_on ), SC-CO₂ containing 10% ethanol yielded the most stable oil. Oxidative stability depended on the type and content of the polar fractions, namely, phenolic compounds and phospholipids. Phenolic compounds acted as natural antioxidants, whereas increased phospholipid contents decreased the stability. Study has shown that the oxidative stability of the oils can be improved at the extraction stage and this may eliminate the need for additive antioxidants.

Phospholipids in foods: prooxidants or antioxidants?

Lipid oxidation is one of the major causes of quality deterioration in natural and processed foods and thus a large economic concern in the food industry. Phospholipids, especially lecithins, are already widely used as natural emulsifiers and have been gaining increasing interest as natural antioxidants to control lipid oxidation. This review summarizes the fatty acid composition and content of phospholipids naturally occurring in several foods. The role of phospholipids as substrates for lipid oxidation is discussed, with a focus on meats and dairy products. Prooxidant and antioxidant mechanisms of phospholipids are also discussed to get a better understanding of the possible opportunities for using phospholipids as food antioxidants.

Effects of endogenous and exogenous micronutrients in rapeseed oils on the antioxidant status and lipid profile in high-fat fed rats

Background

Micronutrients in oil reduce one or more risk factors of cardiovascular diseases, while the contents of micronutrients in oil are relatively poor, which is insufficient to reverse the metabolic disorders at different stages of progress. The aim of this study was to investigate the effects of endogenous micronutrients in optimized cold-pressed rapeseed oil and restoratively added or fortified micronutrients in traditional refined rapeseed oil (restoring micronutrients to be nearly equal to or significantly higher than levels in crude rapeseed oil) on the antioxidant status and lipid profile in high-fat fed rats.

Methods

Male Wistar rats were fed high-fat diets containing different rapeseed oils for 4 weeks, including the standard refined rapeseed oil(SRO), optimized cold-pressed rapeseed oil(CRO) and the traditional refined rapeseed oil with restorative addition or fortification of micronutrients (LF, HF-SRO).

Results

CRO exhibited significant increases in contents of tocopherols (+13%), phytosterols (+34%), polyphenols (+92%) and phospholipids (+725%) compared with SRO, as well as the total antioxidant capacities (+82-125%) (p < 0.05). While the HF-SRO revealed improved antioxidant properties in vitro than the CRO, which was comparable to LF-SRO. Significant improved plasma antioxidant capacities and lipid peroxidation evaluated by T-AOC, GSH, tocopherols and MDA were found in rats fed HF-SRO when compared with CRO and LF-SRO (p < 0.05). Furthermore, HF-SRO also decreased the plasma and hepatic TC levels compared to CRO and LF-SRO, accompanying higher fecal cholesterol excretion (p < 0.05).

Conclusion

The standard refined rapeseed oil with fortification, not restorative addition of micronutrients was comparable to the optimized cold-pressed rapeseed oil in improving the antioxidant status and lipid profile of high-fat fed rats.

Influence of casein-phospholipid combinations as emulsifier on the physical and oxidative stability of fish oil-in-water emulsions

The objective of this study was to investigate the influence of casein (0.3% w/w) and phospholipid (0.5% w/w) emulsifier combinations on the physical and oxidative stability of 10% fish oil-in-water emulsions at pH 7. For that purpose, three phospholipids were evaluated, namely, lecithin (LC), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). The emulsion stabilized with LC showed the best physical stability having the most negative zeta potential and the lowest mean droplet size. In addition, this emulsion was also the least oxidized in terms of peroxide value and concentration of the volatile oxidation product 1-penten-3-ol. This finding is not explained by the antioxidant activity of LC because it showed similar DPPH scavenging activity and lower metal chelating activity than the other phospholipids. Therefore, these results suggested that other factors such as the combination of casein and lecithin, which could result in a favorable structure and thickness of the interfacial layer, prevented lipid oxidation in this emulsion.