Effects of gallic acid alkyl esters and their combinations with other antioxidants on oxidative stability of DHA algae oil

Application of polyphenols as natural antioxidants in edible oils: Current status, antioxidant mechanism, and advanced technology

Oxidation of edible oil, especially those rich in polyunsaturated fatty acids, remains an inevitable problem. Since synthesis antioxidants may have some side effects, countries have been encouraging the development of natural alternatives. Polyphenols are natural compounds demonstrating notable potential in mitigating oil oxidation, but the effectiveness of polyphenols in inhibiting oil oxidation seems to be influenced by their antioxidant mechanisms, components, solubility, and application forms. To promote polyphenol application in oils, the present study aims to provide a comprehensive summary of the antioxidant mechanism of polyphenols in vitro, the common polyphenols employed to inhibit oil oxidation, and the pivotal technologies for incorporating polyphenols with low-fat solubility into oils including esterification modification, co-extraction of polyphenols and oils, nano-emulsion, microcapsules, and oleogels. In addition, a strengths, weaknesses, opportunities, and threats analysis of polyphenol application in oil was conducted. This review will provide a guidance for the application of polyphenols in oils.

Harnessing oleaginous protist Schizochytrium for docosahexaenoic acid: Current technologies in sustainable production and food applications

Docosahexaenoic acid (DHA) exerts versatile roles in nutrition supplementation and numerous health disorders prevention. Global consumption demand for DHA has also been consistently increasing with enhanced health awareness. Oleaginous marine protist Schizochytrium is praised as a potential DHA source due to short growth cycle, convenient artificial culture, harmless to the human body, and easy manipulation of the DHA synthesis pathway. However, factors including strain performances, fermentation parameters, product harvest and extraction strategies, safety and stability maintenance, and also application limitations in health and functional properties affect the widespread adoption of Schizochytrium DHA products. This review provides a comprehensive summary of the current biotechnologies used for tackling factors affecting the Schizochytrium DHA production, with special focuses on Schizochytrium strain improvement technologies, fermentation optimization projects, DHA oil extraction strategies, safety evaluations and stability maintenance schemes, and DHA product application approaches in foods. Inspired by systematic literature investigations and recent advances, suggestive observations composed of improving strain with multiple breeding technologies, considering artificial intelligence and machine learning to optimize the fermentative process, introducing nanoparticles packing technology to improve oxidation stability of DHA products, covering up DHA odor defect with characteristic flavor foods, and employing synthetic biology to construct the structured lipids with DHA to exploit potential functions are formed. This review will give a guideline for exploring more Schizochytrium DHA and propelling the application development in food and health.

Pilot-Scale Enzymatic Conversion of Low Stability, High Free Fatty, Squid Oil to an Oxidatively Stable Astaxanthin-Rich Acylglyceride Oil Suitable for Nutritional Applications

Squid viscera, a byproduct of squid processing, contains oil rich in omega-3 fatty acids (up to 10% by mass) and the antioxidant astaxanthin. However, its high free fatty acid (FFA) content compromises stability. To address this, pilot-scale (200 L) enzymatic re-esterification of squid oil using immobilized lipase (Lipozyme RMIM) was demonstrated, resulting in high acylglyceride yields. The processed oil was analyzed for oxidation kinetics and thermodynamics using Rancimat, fatty acid composition using GC, omega-3 fatty acid positional distribution in the acylglyceride product using 13C NMR, and astaxanthin content. Lipase treatment reduced FFA levels from 44% to 4% and increased acylglycerides to 93% in squid oil. This reduction in FFA was accompanied by significantly increased stability (0.06 to 18.9 h by Rancimat). The treated oil showed no loss in astaxanthin (194.1 µg/g) or omega-3 fatty acids, including docosahexaenoic acid (DHA). DHA remaining predominantly at sn-2 indicated that the naturally occurring positional distribution of this omega-3 FFA was retained in the product. Lipase treatment significantly enhanced oxidative stability, evidenced by improved thermodynamic parameters (Ea 94.15 kJ/mol, ΔH 91.09 kJ/mol, ΔS -12.6 J/mol K) and extended shelf life (IP25 74.42 days) compared to starting squid oil and commercial fish/squid oils lacking astaxanthin. Thus, lipase treatment offers an effective strategy for reducing FFA levels and producing oxidatively stable, astaxanthin-rich acylglyceride squid oil with DHA retained at the nutritionally favored sn-2 position.

Lipophilic antioxidants in edible oils: Mechanisms, applications and interactions

Essential fatty acids (EFAs) in edible oils are crucial for human nutrition. However, their high unsaturation renders edible oils susceptible to oxidation during storage and processing. The addition of lipophilic antioxidants is an effective strategy to inhibit oxidation and safeguard the nutritional integrity of edible oils. This review focused on the diverse mechanisms and applications of lipophilic antioxidants to inhibit oxidation of edible oils. A range of both synthetic and natural lipophilic antioxidants, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), propyl gallate (PG), tocopherols, tocopherols, carotenoids, flavonoids, ascorbyl palmitate, and lipophilic phenolic compounds were discussed. Moreover, lipophilic antioxidant extracts, as the mixture of natural lipophilic antioxidants, can significantly inhibit oil oxidation. The interaction mechanisms of natural lipophilic antioxidants were reviewed. However, compared to synthetic lipophilic antioxidants, the mechanisms and interactions of natural lipophilic antioxidants need to be further studied. Additionally, their stability and solubility, the extraction and purification costs, and the impact on the sensory must be considered when applying natural lipophilic antioxidants to edible oils. This review serves as a timely reference for application of natural lipophilic antioxidants in edible oils, contributing to the development of healthier and more sustainable options.

Effects of Dietary Gallic Acid on Growth Performance, Meat Quality, Antioxidant Capacity, and Muscle Fiber Type-Related Gene Expression in Broiler Chickens Challenged with Lipopolysaccharide

In this study, broilers were selected as the research object to investigate the effects and mechanisms of dietary gallic acid (GA) supplementation on growth performance, meat quality, antioxidant capacity, and muscle fiber-related gene expression. A total of 750 one-day-old healthy 817 male crossbred broiler chickens were divided into five treatment groups, with six replicates per group. Birds in the control (CON) group and LPS-challenged treatment (LPS) group were fed a basal diet, and birds in the other three treatment groups received the basal diet with 150, 300, or 450 mg/kg added GA (GA150, GA300, GA450). On days 14, 17, and 20, chickens in the LPS, GA150, GA300, and GA450 groups received intramuscular injections of LPS, while chickens in the CON group received saline. The results showed that the addition of GA to the diet could effectively increase the average daily gain (ADG) of broilers from 1 to 50 days of age, and had a trend (p = 0.078) of increasing the average daily feed intake (ADFI). Adding 450 mg/kg GA to the diet significantly reduced (p < 0.05) the drip loss and pH value of pectoral muscles 45 min after slaughter, and significantly increased (p < 0.05) the lightness value of pectoral muscles 45 min post-slaughter. With an increase in GA level, the content of total volatile basic nitrogen (TVB-N) in pectoral muscles decreased linearly (p < 0.05), and the concentration of C22:6n-3 increased linearly (p < 0.05). GA effectively improved (p < 0.05) the antioxidant capacity of muscles and significantly increased (p < 0.05) the activity of total superoxide dismutase (T-SOD) in pectoral muscles after LPS stimulation, exhibiting linear and quadratic changes (p < 0.05). It also significantly increased (p < 0.05) the activity of hydrogen peroxide and decreased the activity of glutathione peroxidase (GSH-Px), while it linearly decreased (p < 0.05) the content of malondialdehyde (MDA). In addition, the dietary supplementation of GA significantly increased (p < 0.05) the expression levels of myosin heavy chain (MyHC) I and MyHC IIa in pectoral muscles and significantly decreased (p < 0.05) the expression level of MyHC IIx. In summary, the dietary addition of GA can alleviate the effect of the stress response on the growth performance of broiler chickens and improve antioxidant capacity and meat quality. The appropriate amount of dietary GA at each stage was 300 mg/kg.

Synergistic rosemary extract with TBHQ and citric acid improves oxidative stability and shelf life of peanut

Lipid oxidation often accompanies the processing and storage of peanuts, which causes a serious waste of peanut resources. To solve the problem of being prone to oxidation in peanut processing, a ternary complex antioxidant based on rosemary extract (RE) was constructed to investigate its effect on the oxidative and thermal stability of peanuts, and the inhibition of peanut oxidation by compound antioxidants was revealed by dynamic Arrhenius formula and complexation theory. The results showed that there was a synergistic effect between RE and Tert-butyl hydroquinone (TBHQ), and the antioxidant effects of RE and TBHQ were 4.86 and 1.45 times higher when used in combination than when used alone, respectively. In addition, RE-TBHQ-CA (citric acid) effectively inhibited primary and secondary oxidation of peanuts with a shelf life 8.7 times longer than that of control peanuts. This study provides a novel antioxidant compounding idea, which has a positive effect on improving the quality of peanut and other nut products, prolonging the shelf life and reducing the waste of resources. PRACTICAL APPLICATION: Compounding a complex antioxidant that permits its use in peanuts. It was found that rosemary and TBHQ might have synergistic antioxidant effects. Meanwhile, this combination of RE-TBHQ-CA effectively inhibited the oxidation of peanut oils and prolonged the shelf life of peanuts. RE-TBHQ-CA is a highly efficient complex antioxidant that can reduce the amounts of antioxidants added while maintaining high antioxidant efficiency, which may be useful for the future preservation and storage of nut products as it positively affects the quality and shelf life of the product.

The inhibitory mechanism of 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) formation by ultraviolet-gallic acid (UV-GA) during the oil-frying process of squid

The inhibitory effect of ultraviolet-gallic acid (UV-GA) on carbonyl valence and intermediates and precursors of 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) was investigated to futher clarify the inhibitory mechanism for safety control the quality of oil-fried squid. Ultraviolet C-treated gallic acid (UVC-GA) and ultraviolet B-treated gallic acid (UVB-GA) were produced by ultraviolet 225 nm of band C and 300 nm of band B, respectively. The MeIQx contents in oil-fried squid were significantly higher, and UVC-GA and UVB-GA could significantly inhibit the MeIQx formation and the formation rates of carbonyl valence and precursors (threonine (Thr), creatinine, and glucose). The UVB-GA inhibited formaldehyde formation, while UVC-GA significantly reduced the formaldehyde, acetaldehyde, and 2,5-dimethyl pyrazine contents. In conculsion, UV-GA reduced carbonyl produced from the lipid oxidation to further weaken the catalysis of carbonyl, rendering the MeIQx precursor degrading into the intermediates during Strecker degradation. Thus, the MeIQx formation was inhibited.

Economical downstream processing of microbial polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs) are important nutrients for humans and animals. Microorganisms, such as yeast, filamentous fungi, and microalgae, have successfully been modified to produce PUFAs. Apart from strain improvement and fermentation optimization, efficient and cost-effective downstream processing will determine whether production can advance from the laboratory to the factory.

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.

Impact of α-tocopherol and EGCG on the oxidative stability of margarine: Exploring the possible synergistic effect mechanism

Margarine is a typical water-in-oil (W/O) emulsion fat product. Due to the presence of a water-oil interface, the oil oxidation in the emulsion system is the interface reaction, which is much faster than that in bulk oil and shows different oxidation mechanisms. The analysis of Rancimat and electron spin resonance indicated that α-tocopherol and EGCG show synergistic antioxidant effects in the margarine. After 20 days of accelerated oxidation storage, the antioxidant effect of the compound antioxidant (50 mg/kg α-tocopherol + 350 mg/kg EGCG) on the margarine was significantly higher than that of the single antioxidant α-tocopherol and EGCG. Based on the results of antioxidants partitioning, electrochemistry, fluorescence spectroscopy, and the oxidative decomposition of antioxidants, the possible mechanisms of interaction were the promotion of α-tocopherol regeneration by EGCG, and the fact that α-tocopherol and EGCG could act at different stages and positions of oxidation. This work will contribute to studying antioxidant interactions and can provide valuable suggestions for practical production. PRACTICAL APPLICATION: This study aims to improve the oxidative stability of margarine by adding α-tocopherol and epigallocatechin-gallate (EGCG) individually and in blends. The mechanism of compound antioxidant synergistic inhibition of margarine oxidation was analyzed, providing theoretical basis and scientific basis for the research and practical application of natural antioxidant synergistic mechanism.

Probing the synergistic effects of rutin and rutin ester on the oxidative stability of sardine oil

Multicomponent antioxidant mixture is proved to be highly effective in imparting oxidative stability to the edible oil. It is believed that the high efficacy of those mixtures is due to the synergistic effect exhibited by two or more components. The current study aims to analyse the synergistic effect of a flavonoid and its corresponding ester in improving the oxidative stability of n-3 PUFA rich sardine oil. The oxidative stability of rutin, esterified rutin and their combinations at three different concentrations was studied in sardine oil stored at 37 ºC for 12 days in contact with air under darkness. The combination of rutin and rutin ester showed maximum reduction of 54.2% in oxidation at 100 mg/kg and 150 mg/kg. Perhaps this is the first report on the synergistic effect of a flavonoid and its lipophilized ester for improving the oxidative stability of n-3 PUFA rich oil.

Development of Galloyl Antioxidant for Dispersed and Bulk Oils through Incorporation of Branched Phytol Chain

In this study, a novel galloyl phytol antioxidant was developed by incorporating the branched phytol chain with gallic acid through mild Steglich esterification. The evaluation of the radical scavenging activity, lipid oxidation in a liposomal model, and glycerol trioleate revealed its superior antioxidant activities in both dispersed and bulk oils. Then, the antioxidant capacity enhancement of galloyl phytol was further explored using thermal gravimetry/differential thermal analysis (TG/DTA), transmission electron microscopy (TEM), and molecular modeling. The EC50 values of GP, GPa, and GE were 0.256, 0.262, and 0.263 mM, respectively, which exhibited comparable DPPH scavenging activities. These investigations unveiled that the branched aliphatic chain enforced the coiled molecular conformation and the unsaturated double bond in the phytol portion further fixed the coiled conformation, which contributed to a diminished aggregation tendency and enhanced antioxidant activities in dispersed and bulk oils. The remarkable antioxidant performance of galloyl phytol suggested intriguing and non-toxic natural antioxidant applications in the food industry, such as effectively inhibiting the oxidation of oil and improvement of the quality and shelf life of the oil, which would contribute to the use of tea resources and extending the tea industry chain.

Effects of Ligustrum robustum (Rxob.) Blume extract on the quality of peanut and palm oils during storage and frying process

The potential uses of Ligustrum robustum (Rxob.) Blume extract as a natural antioxidant to protect the quality of different oils during storage and frying process were studied. The results showed that L. robustum extract has been shown to retard the decline in the quality of both oils based on the tests of acid value, peroxide value, p-anisidine value, color, volatile flavor, and fatty acid compositions, and the protective effect of L. robustum extract on the quality of peanut oil was better than that of palm oil. By the component analysis, L. robustum extract was found to have a total phenols content of 140.75 ± 1.52 mg/g, and ligurobustoside C was identified as the main phenolic compound. The thermogravimetric and differential scanning calorimetry results showed that L. robustum extract enhanced the oxidative stability of peanut and palm oils. In addition, Fourier transform infrared results indicated that L. robustum extract had protective effects on the C=C bond and ester bond of oil molecule. Moreover, by using electron spin resonance technique, L. robustum extract showed the ability to inhibit and scavenge alkyl-free radicals in both oils. The present results suggested that L. robustum extract may protect the quality of oils during the storage and frying process by inhibiting the oxidation of unsaturated fatty acids and might be a potential natural antioxidant in the food industry. PRACTICAL APPLICATIONS: The excellent antioxidant ability of Ligustrum robustum (Rxob.) Blume extract on the oxidation of different oils and its low price indicated that it could be used as a new low-cost natural antioxidant in oil processing.

Effects of Tea Polyphenol Palmitate Existing in the Oil Phase on the Stability of Myofibrillar Protein O/W Emulsion

This study aimed to explore the effect of adding different concentrations (0, 0.01%, 0.03%, and 0.05% (w/w)) of tea polyphenol palmitate (TPP) in the oil phase on the emulsifying properties of 5 and 10 mg/mL myofibrillar protein (MP). Particle size results revealed that the flocculation of droplets increased as TPP concentration increased and that droplets in 5 mg/mL MP emulsions (25−34 μm) were larger than in 10 mg/mL MP emulsions (14−22 μm). The emulsifying activity index of 5 mg/mL MP emulsions decreased with increasing TPP concentration. The micrographs showed that the droplets of MP emulsions exhibited extensive flocculation at TPP concentrations >0.03%. Compared with 5 mg/mL MP emulsions, 10 mg/mL MP emulsions showed better physical stability and reduced flocculation degree, which coincided with lower delta backscattering intensity (ΔBS) and Turbiscan stability index values. The flow properties of emulsions can be successfully depicted by Ostwald−de Waele models (R2 > 0.99). The concentrations of TPP and protein affect the K values of emulsions (p < 0.05). Altogether, increased protein concentration in the continuous phase could improve emulsion stability by increasing viscosity, offsetting the adverse effects of TPP to a certain extent. This study is expected to promote the rational application of TPP in protein emulsion products of high quality and acceptability.

Food Ingredients and Nutraceuticals from Microalgae: Main Product Classes and Biotechnological Production

Microalgal products are an emerging class of food, feed, and nutraceuticals. They include dewatered or dried biomass, isolated pigments, and extracted fat. The oil, protein, and antioxidant-rich microalgal biomass is used as a feed and food supplement formulated as pastes, powders, tablets, capsules, or flakes designed for daily use. Pigments such as astaxanthin (red), lutein (yellow), chlorophyll (green), or phycocyanin (bright blue) are natural food dyes used as isolated pigments or pigment-rich biomass. Algal fat extracted from certain marine microalgae represents a vegetarian source of n-3-fatty acids (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), γ-linolenic acid (GLA)). Gaining an overview of the production of microalgal products is a time-consuming task. Here, requirements and options of microalgae cultivation are summarized in a concise manner, including light and nutrient requirements, growth conditions, and cultivation systems. The rentability of microalgal products remains the major obstacle in industrial application. Key challenges are the high costs of commercial-scale cultivation, harvesting (and dewatering), and product quality assurance (toxin analysis). High-value food ingredients are commonly regarded as profitable despite significant capital expenditures and energy inputs. Improvements in capital and operational costs shall enable economic production of low-value food products going down to fishmeal replacement in the future economy.