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

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.