Unsaturated Phosphatidylethanolamine as Effective Synergist in Combination with .ALPHA.-Tocopherol

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.

Frying Performance of Gallic Acid and/or Methyl Gallate Accompanied by Phosphatidylcholine

This study shows the possibility of using gallic acid (GA) and/or methyl gallate (MG) accompanied by phosphatidylcholine (PC) instead of tert-butylhydoquinone (TBHQ) for frying purposes. The antioxidants and PC were added in the concentrations of 1.2 mM and 500-2000 mg/kg, respectively. Oxidative stability index (OSI) and the kinetics of change in conjugated dienes (LCD), carbonyls (LCO), and acid value (AV) were used to assess the antioxidative treatments. GA alone and GA/MG (50:50) plus PC at 2000 mg/kg yielded the same OSI as that of TBHQ (18.4 h). The latter was of the highest frying performance in preventing the formation of LCD (rn = 0.0517/h and tT = 10.6 h vs. rn = 0.0976/h and tT = 4.5 h for TBHQ), LCO (rn = 0.0411/h and tT = 12.7 h vs. rn = 0.15/h and tT = 4.3 h for TBHQ), and hydrolytic products (AVm = 37.8 vs. 24.0 for TBHQ); rn: normalized the maximum rate of LCD/LCO accumulation; tT: the time at which the rate of LCD/LCO accumulation is maximized; AVm: quantitative measure of hydrolytic stability.

The in vitro effects of black soldier fly larvae (Hermitia illucens) oil as a high-functional active ingredient for inhibiting hyaluronidase, anti-oxidation benefits, whitening, and UVB protection

Objective: Larvae of Hermitia illucens, or black soldier fly larvae (BSFL), have been recognized for their high lipid yield with a remarkable fatty acid profile. BSFL oil (SFO) offers the added value of a low environmental footprint and a sustainable product. In this study, the characteristics and cosmetic-related activities of SFO were investigated and compared with rice bran oil, olive oil and krill oil which are commonly used in cosmetics and supplements. Methods: The physicochemical characteristics were determined including acid value, saponification value, unsaponifiable matter and water content of SFO. The fatty acid composition was determined using GC-MS equipped with TR-FAME. The in vitro antioxidant properties were determined using DPPH, FRAP and lipid peroxidation inhibition assays. Antihyaluronidase (anti-HAase) activity was measured by detecting enzyme activity and molecular docking of candidate compounds toward the HAase enzyme. The safety assessment towards normal human cells was determined using the MTT assay and the UVB protection upon UVB-irradiated fibroblasts was determined using the DCF-DA assay. The whitening effect of SFO was determined using melanin content inhibition. Results: SFO contains more than 60% polyunsaturated fatty acids followed by saturated fatty acids (up to 37%). The most abundant component found in SFO was linoleic acid (C18:2 n-6 cis). Multiple anti-oxidant mechanisms of SFO were discovered. In addition, SFO and krill oil prevented hyaluronic acid (HA) degradation via strong HAase inhibition comparable with the positive control, oleanolic acid. The molecular docking confirmed the binding interactions and molecular recognition of major free fatty acids toward HAase. Furthermore, SFO exhibited no cytotoxicity on primary human skin fibroblasts, HaCaT keratinocytes and PBMCs (IC50 values > 200 μg/mL). SFO possessed significant in-situ anti-oxidant activity in UVB-irradiated fibroblasts and the melanin inhibition activity as effective as well-known anti-pigmenting compounds (kojic acid and arbutin, p < 0.05). Conclusion: This study provides scientific support for various aspects of SFO. SFO can be considered an alternative oil ingredient in cosmetic products with potential implications for anti-skin aging, whitening and UVB protection properties, making it a potential candidate oil in the cosmetic industry.

Digestibility and oxidative stability of plant lipid assemblies: An underexplored source of potentially bioactive surfactants?

Most lipids in our diet come under the form of triacylglycerols that are often redispersed and stabilized by surfactants in processed foods. In plant however, lipid assemblies constitute interesting sources of natural bioactive and functional ingredients. In most photosynthetic sources, polar lipids rich in ω3 fatty acids are concentrated. The objective of this review is to summarize all the knowledge about the physico-chemical composition, digestive behavior and oxidative stability of plant polar lipid assemblies to emphasize their potential as functional ingredients in human diet and their potentialities to substitute artificial surfactants/antioxidants. The specific composition of plant membrane assemblies is detailed, including plasma membranes, oil bodies, and chloroplast; emphasizing its concentration in phospholipids, galactolipids, peculiar proteins, and phenolic compounds. These molecular species are hydrolyzed by specific digestive enzymes in the human gastrointestinal tract and reduced the hydrolysis of triacylglycerols and their subsequent absorption. Galactolipids specifically can activate ileal break and intrinsically present an antioxidant (AO) activity and metal chelating activity. In addition, their natural association with phenolic compounds and their physical state (Lα state of digalactosyldiacylglycerols) in membrane assemblies can enhance their stability to oxidation. All these elements make plant membrane molecules and assemblies very promising components with a wide range of potential applications to vectorize ω3 polyunsaturated fatty acids, and equilibrate human diet.

Dioleylphosphatidylcholine increases the antioxidant properties of ascorbyl palmitate in bulk oils compared to other hydrophilic and lipophilic antioxidants

Effects of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and moisture on the solubility of hydrophilic and lipophilic antioxidants were evaluated in medium-chain triacylglycerol (MCT) by 2,2-diphenyl-1-picrylhydrazyl (DPPH) reactivity. Next, we assessed the oxidative stability of antioxidant-containing corn oil depending on the presence of DOPC. The critical micelle concentration (CMC) of DOPC decreased when the moisture content was increased from 300 to 495 mg/kg oil and gradually increased when the moisture was further increased to 2122 mg/kg oil. As the DOPC concentration increased, the DPPH reactivity of ascorbyl palmitate in the control MCT increased by 10.23-fold, whereas that of the ascorbic acid and α-tocopherol was slightly affected both by the DOPC and moisture content. Presence of DOPC significantly increased the oxidative stability of ascorbyl palmitate-containing corn oil (p < 0.05), whereas these synergistic antioxidant effects were not observed in ascorbic acid-or α-tocopherol-containing corn oil. In conclusion, DOPC displays a synergistic antioxidant effect with ascorbyl palmitate in bulk oil.

Impact of Phospholipid-Tocopherol Combinations and Enzyme-Modified Lecithin on the Oxidative Stability of Bulk Oil

Phosphatidylethanolamine (PE) and phosphatidylserine (PS) have been shown to increase the antioxidant activity of α-tocopherol. This study investigated the ability of PE or PS to increase the antioxidant activity of different tocopherol homologues in bulk oil. In addition, the ability of a phospholipase-D-modified lecithin (high in PE) to increase the activity of α-tocopherol was determined. Results showed that PE was much more effective than PS at increasing the activity of the tocopherol homologues. The combination of mixed tocopherols with PE presented the greatest increase in antioxidant activity, with hydroperoxides and hexanal lag phases increasing 54 and 53 days compared to the mixed tocopherols alone. Phospholipase-D-modified lecithin increased the antioxidant activity of α-tocopherol in stripped bulk oil as well as a commercially refined oil with no added tocopherols. The study indicates that PE is a powerful tool to increase the antioxidant activity of tocopherols in bulk oil and that modification of lecithin to increase the PE concentration could be a commercially viable option to functionalize lecithin, so that its ability to inhibit lipid oxidation increases in bulk oils.

Effective Prevention of Oxidative Deterioration of Fish Oil: Focus on Flavor Deterioration

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both abundant in fish oil, are known to have significant biochemical and physiological effects primarily linked to the improvement of human health, especially cardiovascular and brain health. However, the incorporation of fish oil into foods and beverages is often challenging, as fish oil is very easily oxidized and can cause undesirable flavors. This review discusses this rapid formation of the fishy and metallic off-flavors, focusing especially on an early stage of fish oil oxidation. Although oxidative stability and quality of commercialized fish oil have improved over the past few years, there is a still a problem with its application: Flavor deterioration can be found even at very low oxidation levels. This review also notes the effective way to inhibit the formation of the volatile compounds responsible for the flavor deterioration.

The New Paradigm for Lipid Oxidation and Insights to Microencapsulation of Omega-3 Fatty Acids

The consumption of omega-3 fatty acids provides a wide range of health benefits. However, the incorporation of these fatty acids in foods is limited because of their high oxidative instability. A new paradigm has emerged to better explain the oxidation mechanism of polyunsaturated fatty acids, which will be discussed here with reference to bulk lipids considered a special case of water in oil microemulsion. This paradigm suggests that lipid oxidation reactions are initiated by heterogeneous catalysis by metal oxides followed by the formation of micelles containing initial hydroperoxides, water, and other amphiphilic compounds. The induction period comes to the end when the formed micelles reach a critical micelle concentration and start to decompose opening the way to intense free radical reactions. Antioxidants and synergists extend the induction period not only by scavenging free radicals but also by stabilizing the micelles. With better understanding of the lipid oxidation mechanism, a tailored choice of antioxidants and synergistic combinations, and efficient encapsulation methods may be optimized to provide stable encapsulates containing highly n-3 polyunsaturated fatty acids. Smart processing and encapsulation technologies utilizing properly stabilized oils as well as optimized packaging parameters aiming to enhance n-3 fatty acid stability by smart selection/design of antioxidants, control of the interfacial physics and chemistry, and elimination of surface oil are needed for this purpose.

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.

Impact of phosphatidylethanolamine on the antioxidant activity of α-tocopherol and trolox in bulk oil

The amphiphilic phospholipids dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE), can form reverse micelles in bulk oils, which affects lipid oxidation chemistry. Previous studies showed that reverse micelles formed by DOPC and DOPE shorten the oxidation lag phase of stripped soybean oil. This study examined how these reverse micelles influence the activity of primary antioxidants such as the nonpolar α-tocopherol and the polar trolox in stripped and commercial soybean oils. The results showed that DOPC reverse micelles decreased the activity of 100 μM α-tocopherol or trolox. On the other hand, DOPE increased the antioxidant activity of both α-tocopherol and trolox. The polar trolox exhibited better antioxidant activity than the nonpolar α-tocopherol in the presence of both DOPC and DOPE reverse micelles because trolox partitioned more at the interfaces, which was confirmed by a fluorescence steady state study. Different ratios of DOPE to DOPC were added to oil containing 100 μM α-tocopherol, and antioxidant activity increased with increasing DOPE/DOPC ratio. Addition of DOPE to commercial oil inhibited lipid oxidation, whetrsd DOPC was ineffective. HPLC showed that DOPE regenerated α-tocopherol. This study indicates that the antioxidant activity of tocopherols could be improved by utilizing phosphatidylethanolamine (PE) to engineer the properties of reverse micelles in bulk oil.

Synergistic antioxidant activity of milk sphingomyeline and its sphingoid base with α-tocopherol on fish oil triacylglycerol

The effects of milk phospholipids (PLs), sphingolipids (SLs), and their sphingoid backbone on the oxidation of fish oil triacylglycerol (TAG) were examined with or without α-tocopherol. All compounds had little effect on the TAG oxidation in the absence of α-tocopherol. On the other hand, they could act synergistically with α-tocopherol. The highest synergistic activity was shown by sphingoid bases, followed by sphingomyelin (SPM) and other amine-containing PLs and SLs. This result showed that the synergistic activity increased with an increasing concentration of amine group of PLs, SLs, or sphingoid bases in the reaction mixture. The comparison of changes in α-tocopherol content in fish oil TAG and tricaprylin suggested that antioxidant compounds would be formed from the amine group and the lipid oxidation products in a mild oxidation condition controlled by α-tocopherol.

Minor components in food oils: a critical review of their roles on lipid oxidation chemistry in bulk oils and emulsions

Food oils are primarily composed of triacylglycerols (TAG), but they may also contain a variety of other minor constituents that influence their physical and chemical properties, including diacylglycerols (DAG), monoacylglycerols (MAG), free fatty acids (FFA), phospholipids (PLs), water, and minerals. This article reviews recent research on the impact of these minor components on lipid oxidation in bulk oils and oil-in-water emulsions. In particular, it highlights the origin of these minor components, the influence of oil refining on the type and concentration of minor components present, and potential physicochemical mechanisms by which these minor components impact lipid oxidation in bulk oils and emulsions. This knowledge is crucial for designing food, pharmaceutical, personal care, and other products with improved stability to lipid oxidation.

Oxidative stability at high temperatures of oleyol and linoleoyl residues in the forms of phosphatidylcholines and triacylglycerols

An investigation was carried out into the stability of fatty acyl groups to heat-induced oxidative changes as affected by their chemical environment. The behavior of oleic and linoleic acyl groups when esterified in triacylglycerols (TAGs) and phosphatidylcholines (PCs) was evaluated. The monitoring of the oxidative degradation using liquid chromatography-mass spectrometry (LC-MS) showed that fatty acyl groups are less likely to be oxidized when in the form of PCs than when in the form of TAGs. In addition, oxidation products from PCs were more stable than those from TAGs. This finding strengthens the idea that the choline group in PCs increases the stability of fatty acyl groups to oxidation in comparison to TAGs.

The role of plasmalogen in the oxidative stability of neutral lipids and phospholipids

The role of ethanolamine plasmalogen extracted from bovine brain (BBEP) in maintaining oxidative stability of bulk soybean oil and liposome made with egg phospholipids (PL) was studied. In a purified soybean oil (PSO), the addition of 200 and 1000 ppm of BBEP promoted lipid oxidation at rates of 0.037 and 0.071 (all rates in ln (PV) h(-1), and PV stands for peroxide value), whereas soy lecithin (SL) added in the same amount showed a trend similar to the PSO blank, which had an oxidation rate of 0.025. The PSO with BBEP was susceptible to cupric ion catalyzed oxidation, in that the oil was oxidized much more quickly than the PSO with SL and cupric ion. In commercial soybean oil (CSO) with the presence of tocopherols, SL at 1000 ppm acted synergistically as an antioxidant with the natural tocopherols, but addition of BBEP accelerated lipid oxidation, as evidenced by the oxidative stability index (OSI) test. In the egg PL liposome, the BBEP caused a fast breakdown of the lipid hydroperoxides and consequently promoted more thiobarbituric acid reactive substance (TBARS) formation. The PL oxidation in the presence of copper in the liposome was not affected by the BBEP, which indicates that the hypothesis of ethanolamine plasmalogen (EthPm) chelating cupric ion as the antioxidation mechanism was not supported. The addition of cumene hydroperoxide to the egg PL liposome promoted lipid oxidation, as indicated by a fast development of PV and TBARS. However, the result with cumene hydroperoxide failed to differentiate the effect of BBEP and SL and their concentration on lipid oxidation. On the basis of the observations from this study, we conclude that EthPm is not an antioxidant but rather a pro-oxidant in a bulk lipid system, and it has no significant antioxidant effect for PL oxidation in the liposome.