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

Migration of tocopherols from the oil phase to the oil-water interface using phospholipids improved the oxidative stability of O/W emulsions

The purpose of this research was to effectively migrate tocopherols (T) to the oil-water interface layer (oxidation site) by combining hydrophobic T with amphiphilic phospholipids (P) to improve the oxidative stability of O/W emulsions. Firstly, it was confirmed that the antioxidant ability of TP combinations exhibited synergistic effects in O/W emulsions by measuring lipid hydroperoxides and thiobarbituric acid-reactive species. Moreover, the introduction of P into O/W emulsions to improve the distribution of T at the interfacial layer was confirmed by centrifugation and confocal microscopy methods. Subsequently, the possible mechanisms of synergistic interaction between T and P were described by fluorescence spectroscopy, isothermal titration calorimetry, electron spin resonance, quantum chemical methods and the variation of minor constituents during storage. This research revealed an in-depth insight into the antioxidant interaction mechanism of TP combinations using experimental and theoretical approaches, which provided theoretical guidance for developing emulsion products with better oxidative stability.

Interfacial behavior of gallic acid and its alkyl esters in stripped soybean oil in combination with monoacylglycerol and phospholipid

The effect of gallic acid alkyl esters and their combination with monoacylglycerol (MAG) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) on the formation of hydroperoxides and hexanal were determined during the oxidation of stripped soybean oil. Interfacial tension, water content, and droplet size were evaluated to monitor the physical properties of the oil system. Adding MAG and DOPC, especially MAG/DOPC, to the oil promoted the partitioning of antioxidants into the water-oil interfaces by further reducing the interfacial tension. The stripped oil containing methyl gallate (MG) accompanied by MAG/DOPC had lower values of the critical micelle concentration of hydroperoxides and larger micellar size at the induction period. This confirms that MG was able to more effectively reduce the free hydroperoxides concentration and inhibit them in an interfacial way. The conjunction of surfactants has been shown as a promising strategy to improve the interfacial and antioxidant activity of gallates in the oxidative stability of soybean oil.

Antioxidant properties of lipid concomitants in edible oils: A review

Edible oils are indispensable for human life, providing energy and necessary fatty acids. Nevertheless, they are vulnerable to oxidation via a number of different mechanisms. Essential nutrients deteriorate as well as toxic substances are produced when edible oils are oxidized; thus, they should be retarded wherever possible. Lipid concomitants have a strong antioxidant capacity and are a large class of biologically active chemical substances in edible oils. They have shown remarkable antioxidant properties and were documented to improve the quality of edible oils in varied ways. An overview of the antioxidant properties of the polar, non-polar, and amphiphilic lipid concomitants present in edible oils is provided in this review. Interactions among various lipid concomitants and the probable mechanisms are also elucidated. This review may provide a theoretical basis and practical reference for food industry practitioners and researchers to understand the underlying cause of variations in the quality of edible oils.

Bicarbonates and carbonates as antioxidants in vegetable oils at frying temperatures

Antioxidant activity of bicarbonates and carbonates including NaHCO₃ , Na₂ CO₃ , KHCO₃ , and K₂ CO₃ was evaluated in soybean oil (SBO) at 180°C. KHCO₃ and K₂ CO₃ had stronger activity than NaHCO₃ and Na₂ CO₃ . KHCO₃ (5.5 mEq/L, 0.060 wt.%) and K₂ CO₃ (5.5 mEq/L, 0.041 wt.%) were more effective than 0.02 wt.% tert-butylhydroquinone (TBHQ) in preventing oxidation of SBO. While the antioxidant activity of KHCO₃ and K₂ CO₃ increased with increasing their concentrations up to 5.5 mEq/L, it decreased at 11 mEq/L. KHCO₃ and K₂ CO₃ were also effective in preventing oxidation of other vegetable oils including avocado, canola, corn, high oleic soybean, and olive oils. Correlation tests conducted with the results from the six oils showed that KHCO₃ and K₂ CO₃ had weak to moderate positive correlations with γ- and δ-tocopherols. In a separate study in stripped SBO, it was found that KHCO₃ had a synergistic effect with α-tocopherol, but not with γ- and δ-tocopherols. KHCO₃ had additive or synergistic effect with rosemary extract, epigallocatechin gallate, ascorbic acid, and ascorbyl palmitate. Antioxidant activity of KHCO₃ was confirmed in frying of potato cubes in SBO and canola oil. Although more studies should be conducted for better understanding of the mechanisms and factors affecting the antioxidant activity of bicarbonates and carbonates, this study demonstrated that they could serve as antioxidants or co-antioxidants of other antioxidants in frying. PRACTICAL APPLICATION: Inorganic salts including NaHCO₃ , KHCO₃ , Na₂ CO₃ , and K₂ CO₃ hadstrong antioxidant activity in vegetable oils at frying temperatures when they wereadded as powder. Antioxidant activity of 0.06 wt.% KHCO₃ was higherthan that of 0.02 wt.% TBHQ in soybean oil and canola oil during frying potato. KHCO₃ had additive orsynergistic effect with rosemary extract, epigallocatechin gallate, ascorbicacid, and ascorbyl palmitate indicating that these inorganic salts can be usedas co-antioxidants to enhance the antioxidant activity of existing antioxidantswhile they can be used alone as well.

Enzymatic Modification of Lecithin for Improved Antioxidant Activity in Combination with Tocopherol in Emulsions and Bulk Oil

Oxidized α-tocopherol can be regenerated by phosphatidylethanolamine (PE), but current commercial sources of PE are too expensive for use as a food additive. The present study aims to determine the optimal reaction conditions for generating high PE lecithin (MHPEL) enzymatically and to validate the MHPEL's synergism with tocopherol in delaying lipid oxidation in an oil-in-water emulsion system at pH 7 and 4 and in bulk oil. Under optimal conditions of pH 9.0, 37 °C and 4 h, a MHPEL with ∼71.6% PE was obtained from 96% phosphatidylcholine lecithin using phospholipase D from Streptomyces chromofuscus. Mixed tocopherols (300 μmol/kg oil) and MHPEL (1500 μmol/kg oil) synergistically increased both the hydroperoxide and hexanal lag phase of lipid oxidation in stripped soybean oil-in-water emulsions at pH 7 by 3 days. At pH 4, this combination increased the hydroperoxide and hexanal lag phases by 3 and 2 days, respectively. The combination of 50 μmol/kg oil α-tocopherol and 1000 μmol/kg oil MHPEL also synergistically increased the hydroperoxide (5 days) and hexanal (4 days) lag phases in stripped bulk soybean oil. This approach represents a potential clean-label antioxidant system that could have commercial applications to decrease food waste.

The Use of Sea Buckthorn Processing Products in the Creation of a Functional Biologically Active Food Emulsion

The current trend in dietary supplements and functional foods is the use of lipophilic bioactive compounds. The sea buckthorn (Hippóphae rhamnoídes) contains some such compounds: polyunsaturated fatty acids, tocopherols, and carotenoids. Lipophilic components are best distributed using oil-in-water emulsions, which ensures their high bioavailability. A significant property of emulsions is colloidal and oxidative stability, so the choice of emulsifiers that have both surface-active properties and antioxidant activity is an important area of research for making new types of food emulsions. The purpose of this study is the development and refinement of an emulsified biologically active food additive containing sea buckthorn products (pulp, juice, and oil) and stabilized with soy phospholipids. We studied the fruits of Chuyskaya, Orange, and Prevoskhodnaya sea buckthorn varieties growing in the Altai Territory. As we analyzed their composition, we chose the Chuyskaya variety for making the emulsion. The fruits contain 5.30 ± 0.1% of lipids including 16.8 ± 0.5 mg/100 g of carotenoids and 10.5 ± 0.5 mg/100 g of tocopherols. To choose the emulsifier we studied the fractional and fatty acid composition of the soy and sunflower phospholipids with different hydrophilic-lipophilic balances (HLB). We made the emulsions containing sea buckthorn oil and pulp of its different layers, soybean oil, and phospholipids by dispersion using an HG-15D homogenizer. The study of the colloidal stability showed that the most stable (99.5%) are the emulsions containing a mixture of hydrolyzed soybean phospholipids (HLB = 7) and fractionated soybean phospholipids (HLB = 3). The best ratio is 40:60. We examined the oxidative stability of the emulsions by provoking accelerated oxidation. The emulsions containing 1.5% of a soy phospholipids mixture showed the best oxidative stability. The resulting direct oil-in-water fine emulsion contains polyunsaturated fatty acids (PUFAs), tocopherols, β-carotene, and essential phospholipids. For this reason, the emulsion can be used to make biologically active food supplements (also encapsulated) and as part of special nutrients.

Effect of polyglycerol polyricinoleate on the inhibitory mechanism of sesamol during bulk oil oxidation

In this study, effects of sesamol on improving the oxidative stability of sunflower oil and its oil-in-water emulsion was investigated. To investigate the kinetic parameters related to the initiation and propagation stages of oxidation, a sigmoidal-model was used. Sesamol exhibited higher antioxidant activity in sunflower oil-in-water emulsion than that of sunflower oil. In both sunflower oil and sunflower oil-in-water emulsion, the inhibitory effect of sesamol against lipid oxidation continued even after the induction period. To improve the efficiency of sesamol in sunflower oil, polyglycerol polyricinoleate (PGPR) was incorporated into the functional environment of the sesamol. Sesamol exhibited a synergistic effect with PGPR during both initiation (synergistic effect of 68.87%) and propagation (synergistic effect of 36.84%) stages. Comparison of the size of reverse micelles in samples containing PGPR with those without PGPR revealed that PGPR can enhance the efficiency of sesamol by increasing the acceptance capacity of lipid hydroperoxides in reveres micelles structures. This can result in enhancing the effective collisions between sesamol and lipid hydroperoxides in the presence of PGPR. The water produced as a major byproduct of oxidation played a key role on the antioxidant activity of sesamol alone or in combination with PGPR during oxidation process.

Production of a High-Phosphatidylserine Lecithin That Synergistically Inhibits Lipid Oxidation with α-Tocopherol in Oil-in-Water Emulsions

Phosphatidylserine (PS) was shown to work synergistically with tocopherols to extend the shelf life of oil-in-water emulsions. However, the high cost of PS prevents it from being used as a food additive. This work investigated the potential use of a high-PS enzyme-modified lecithin to be used along with α-tocopherol to extend the lag phase of oil-in-water emulsions stabilized using Tween 20. Phospholipase D from Streptomyces sp. and L-serine were used to modify lecithin to increase the PS concentration. Enzyme activity was optimized as a function of pH and temperature using high-phosphatidylcholine (PC) soybean, sunflower, or egg lecithins. Under optimal conditions, the final PS concentrations were 92.0 ± 0.01%, 88.0 ± 0.01%, and 63.0 ± 0.02% for high-PC soybean, sunflower, and egg lecithins, respectively. α-Tocopherol (3.0 µmol/kg emulsion) alone increased the lag phase of hydroperoxide and hexanal lag phases by 3 and 4 days compared to the control. Phospholipase-D-modified high-PS soy lecithin increased hydroperoxide and hexanal lag phases by 3 and 4 days, respectively. The addition of phospholipase-D-modified high-PS sunflower and egg lecithin did not have any considerable effects on lag phases compared to the control. The combination of phospholipase-D-modified high-PS lecithins (15.0 µmol/kg emulsion) and α-tocopherol (3.0 µmol/kg emulsion) increased the antioxidant activity of α-tocopherol, increasing the hydroperoxide and hexanal lag phase by 6 and 9 days for soy, 5 and 7 days for sunflower, and 4 and 6 days for egg lecithin, respectively. All phospholipase-D-modified high-PS lecithin−tocopherol combinations resulted in synergistic antioxidant activity (interaction index > 1.0), except for α-tocopherol and high-PS egg lecithin, which showed an additive effect. This research showed that the combination of enzyme-modified high-PS lecithin and α-tocopherol could be an effective and commercially viable clean label antioxidant strategy to control lipid oxidation in emulsions.

Simultaneous quantification of 24 aldehydes and ketones in oysters (Crassostrea gigas) with different thermal processing procedures by HPLC-electrospray tandem mass spectrometry

Aldehydes and ketones are secondary oxidation products resulting from lipid oxidation that occurs during food processing. These small molecule compounds not only have an impact on the quality, odor and flavor of food, but also play a role in the pathogenesis of many human diseases. In this study, a HPLC-MS/MS analytical method was developed and validated for the simultaneous determination of 24 aldehydes and ketones. The coefficients of determination (R²) for all aldehydes and ketones were higher than 0.9975 at the range of 0.2-2000 ng/mL. The recoveries were in the range 71.20-108.13% with RSD < 10%. The method was tested by analyzing lipids from oysters with different thermal processing (boiling, frying, roasting and air frying) procedures; the highest concentration for saturated aldehydes and ketones while the highest content of unsaturated aldehydes in boiling treatment. Meanwhile, fatty acid oxidative decomposition was in agreement with aldehydes and ketones formation. Moreover, principal component analysis, orthogonal partial least-squares discriminant analysis and variable importance in projection value showed that lipid oxidation is positively related to the formation of a variety of aldehydes and ketones.

Application of Antioxidants as an Alternative Improving of Shelf Life in Foods

Oxidation is the main problem in preserving food products during storage. A relatively novel strategy is the use of antioxidant-enriched edible films. Antioxidants hinder reactive oxygen species, which mainly affect fats and proteins in food. At present, these films have been improved by the addition of micro- and nanoliposomes coated with carbohydrate polymers, which are not hazardous for human health and can be ingested without risk. The liposomes are loaded with different antioxidants, and their effects are observed as a longer storage time of the food product. The synergy of these methodologies and advances can lead to the displacement of the protective packaging used currently, which would result in food products with functional properties added by the films, an increase in shelf life, and an improvement to the environment by reducing the amount of waste.

Combination of natural strategies to improve the oxidative stability of echium seed oil

Echium seed oil is an alternative source of omega 3 fatty acids but it is highly susceptible to oxidation. A combination of three natural strategies was proposed in this study aiming to improve the oxidative stability of echium oil obtained by pressing (PO) or solvent extraction (PSO), kept in the storage condition for 180 days or during the consumption for 30 days. Our results showed that the reduction of temperature was sufficient to keep the oil stable during storage for both samples. During the consumption time, the best stability was achieved by adding a mixture of antioxidants, composed of sinapic (500 ppm), ascorbic (250 ppm), and citric (150 ppm) acids, and/or 20% of high oleic sunflower oil. The combined strategies promoted a 34 to 80% reduction of peroxide value and 0 to 85% reduction of malondialdehyde concentrations in the samples, showing to be a feasible and natural alternative to improve the oxidative stability of echium oil. PRACTICAL APPLICATION: Our study successfully applied an optimized combination of simple and low-cost strategies to enhance the chemical stability of echium seed oil. As the use of echium oil expands around the world, the oil industry and final consumers may benefit from our results to increase the oil shelf-life.

Immobilization of Lipozyme TL 100L for methyl esterification of soybean oil deodorizer distillate

An immobilization method for binding cross-linked enzyme aggregates of Lipozyme TL 100L on macroporous resin NKA (CLEA-TLL@NKA) was developed in this study. The esterification activity of CLEA-TLL@NKA reached 6.4 U/mg. The surface structure of immobilized lipase was characterized by scanning electron microscopy. Methyl esterification reaction of soybean oil deodorizer distillate (SODD) was catalyzed by CLEA-TLL@NKA, which the conversion rate reached 98% and its activity retained over 90% after 20 batches of reaction. Compared with the commercial enzyme Lipozyme TLIM, half-life (t _1/2) of CLEA-TLL@NKA increased by 25 times and the catalytic activity increased by approximate 10 times. Thus, CLEA-TLL@NKA had high catalytic activity, good operational stability, and potential industrial application in the field of oil processing.

Free Radical Scavenging Activity of Carbonyl-Amine Adducts Formed in Soybean Oil Fortified with Phosphatidylethanolamine

Non-enzymatic browning reactions between lipid aldehydes and aminophospholipids might play an important role in the oxidative stability of cold-pressed vegetable oils. We, therefore, aimed to study the Maillard-type reaction between hexanal, a lipid oxidation product of linoleic acid, and phosphatidylethanolamine (PE (16:0/18:1)) at a ratio of 2:1 at conditions representative of the extraction of cold-pressed soybean oils (CPSBO) and determine the radical scavenging activity of the carbonyl-amine adducts with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The reaction product, 2-pentyl-3,5-dibutyl-dihydropyridine, could be identified by means of LC-ESI-QTOF-MS/MS. The formation of this nitrogen-containing heterocycle significantly increased with time and temperature (p < 0.05). The products formed during the carbonyl-amine reaction between PE (16:0/18:1) and hexanal at 60 °C showed a radical scavenging activity of approximately 20% (p < 0.05). The fraction, containing 2-pentyl-3,5-dibutyl-dihydropyridine, contributed to, but was not solely responsible for, the radical scavenging activity (p < 0.05). Incubation of CPSBO fortified with PE (16:0/18:1) at 60 °C for 60 min had the strongest radical scavenging activity of 85.1 ± 0.62%. Besides 2-pentyl-3,5-dibutyl-dihydropyridine, other carbonyl-amine adducts might impact the radical scavenging activity of CPSBO as well. The oxidative stability of CPSBO might be increased by promoting the formation of carbonyl-amine reaction products, such as 2-pentyl-3,5-dibutyl-dihydropyridine.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

Combining Cell Surface Display and DNA-Shuffling Technology for Directed Evolution of Streptomyces Phospholipase D and Synthesis of Phosphatidylserine

Phospholipids have been widely used in food, medicine, cosmetics, and other fields because of their unique chemical structure and healthcare functions. Phospholipase D (PLD) is a key biocatalyst for the biotransformation of phospholipids. Here, an autodisplay expression system was constructed for rapid screening of mutants, and PLD variants were recombined using DNA shuffling technology and three beneficial mutations were obtained. The results of enzymatic performance and sequence information comparison indicated that C-terminal amino acids exerted a greater impact on the correct folding of PLDs, and N-terminal amino acids are more important for catalytic reaction. The best-performing recombinant enzyme in transphosphatidylation reactions was Recom-34, with a phosphatidylserine content accounting for 80.3% of total phospholipids and a 3.24-fold increased conversion rate compared to the parent enzyme. This study demonstrates great significance for screening ideal biocatalysts, facilitating soluble expression of inclusion body proteins, and identifying key amino acids.

Structural effect of amine N-oxides on the facilitation of α-glucosidase-catalyzed hydrolysis reactions

Activation and stabilization of enzymes is an important issue in their industrial application. We recently reported that synthetic betaines, derived from cellular metabolites, structure-dependently increased the activity and stability of various enzymes including hydrolases, oxidases, and synthetases simply by mixing them into the reaction buffer. In this report, we focus on amine N-oxides, which are similarly important metabolites in cells with a highly polarized N-oxide bond, and investigate their enzyme stabilization and activation behavior. It was revealed that synthetic amine N-oxides structure-dependently activate α-glucosidase-catalyzed hydrolysis reactions similarly to betaines. The subsequent comparison of the kinetic parameters, the optimal concentration range for activation, and the maximal activity, suggested that amine N-oxides facilitate hydrolysis reactions via the same mechanism as betaines, because no differences were confirmed. However, the enzyme stabilization effect of amine N-oxides was slightly superior to that of betaines and the temporal stability of the enzyme in aqueous solutions was higher in the low amine N-oxide concentration range. The rheological properties, CD spectra, and dynamic fluorescence quenching experiments suggested that the suppression of unfavorable conformational perturbation was related to the difference in the hydration environments provided by the surrounding water molecules. Thus, we clarified that amine N-oxides facilitate enzyme reactions as a result of their similarity to betaines and provide a superior stabilizing effect for enzymes. Amine N-oxides show potential for application in enzyme storage and long-term reactions.