Evaluation on the oxidative stability of edible oil by electron spin resonance spectroscopy

A New Insight into the Weight Gain Method to Monitor and Evaluate Lipid Peroxidation

The kinetics of change in peroxide value and weight gain were simultaneously studied during the peroxidation of three vegetable oils of various chemical compositions. The initiation and propagation oxidizability parameters Oi (kg mEq-1 h2) and rn (h-1) of the canola, corn, and peanut oils were calculated to be 412 and 0.0894, 160 and 0.0641, and 36.1 and 0.0304, respectively. The weight-based parameter Oiw ranked the oils (103,000, 51,000, and 8000% h2, respectively) as the parameter Oi did. However, the equivalent parameter rnw (0.0680, 0.1198, and 0.1875 h-1, respectively) provided a reverse order than that of the parameter rn. This was attributed to the fact that the value of rn represents the formation and decomposition of lipid hydroperoxides in general, whereas the value of rnw actually represents the overall tendency of an oil to the formation and polymerization of lipid hydroperoxides.

Enhancing walnut butter with a pea protein isolate-pectin-pterostilbene complex: Physicochemical properties and stability analysis

To explore the potential applications of pea protein isolate-pectin-pterostilbene complex (PPI-PEC-PT) in the sauce industry, its solubility, antioxidant capacity and oxidative stability were measured. The results indicated that PPI-PEC-PT exhibited a solubility of 77.67 %, more than double that of PPI-PT (31.93 %). The DPPH radical scavenging capacity of PPI-PEC-PT reached up to 78.52 % at a concentration of 50 μg/mL. After accelerated oxidation (60 °C, 7 days), the peroxide value (8.15 mmol/L) and malondialdehyde content (11.50 mmol/L) of PPI-PEC-PT emulsion were significantly lower than those of PPI. Additionally, when applied to walnut butter, PPI-PEC-PT significantly enhanced its gel properties. In conclusion, PPI-PEC-PT could not only serve as a natural antioxidant but also be utilized as a food additive to enhance the gelling properties of products in the food industry.

Characterization of the evolution of free radicals and TALAs in linseed oil during heat treatment

Various studies have demonstrated that employing ESR spin trapping to detect free radicals yields valuable insights into the vulnerability of bulk oils to oxidation. Consequently, this method can be employed to assess and compare the oxidative stability of different samples. This study was conducted to investigate the production and transformation of free radicals and trans isomers in linseed oil when subjected to different temperatures and durations of heating. These analyses revealed that the peak levels of free radicals PBN adducts were evident in linseed oil heated to 120 °C, while these levels decreased within 90 min and were absent at a higher temperature of 180 °C. Free radical PBN adducts were readily degraded at 180 °C. Levels of heat-induced trans isomers rose in linseed oil samples with rising temperatures but began to degrade at temperatures exceeding 240 °C partially. The content examination of these trans isomers revealed that the double bonds located at positions 9 and 15 exhibited a higher susceptibility to isomerization compared to the double bond at position 12. Furthermore, the values of k and Ea indicated that the synthesis of tri-trans-α-linolenic acid (TALAs) was more challenging compared to double-TALAs, and double-TALAs were more challenging than single-TALAs. This was because the tri-TALAs has a higher Ea value than the mono-TALAs and double-TALAs. The study has demonstrated that subjecting linseed oil to high-temperature heating leads to the production of free radicals and trans isomers. And PBN radical adduct is unstable at 180 °C and the double bonds at positions 9 and 15 could be isomerized more easily than that at position 12. These results indicated that controlling the formation of free radicals and single-TALAs isomers may be the key way to reduce the trans isomers of linolenic acid during cooking oil heating. In the follow-up study, we found that VE, VK3, ethyl caffeic acid and resveratrol had significant inhibitory effects on the formation of TALAs of linolenic acid, and the highest inhibitory rate of resveratrol with 5% addition could be reached to 30.86%. The above substances can be applied to the thermal processing of linseed oil to prevent the formation of TALAs.

Effect of Vacuum Roasting on Total Selenium Content of Selenium-Enriched Rapeseed, Maillard Reaction Products, Oxidative Stability and Physicochemical Properties of Selenium-Enriched Rapeseed Oil

Selenium-enriched rapeseed (SER) is an emerging oil seed. Roasting is beneficial in improving oil yield and promoting the release of micronutrients into SER oil, but high temperatures and dry air lead to selenium loss and fatty acid degradation in SER. To minimize the selenium loss and improve the SER oil quality, this study investigated the effects of vacuum (VC) roasting (90-170 °C for 30 min) on the SER selenium content, Maillard reaction products, oxidative stability, and physicochemical properties of SER oil, with conventional dry air (DA) roasting as the control. The results showed that the selenium loss in VC-roasted SER meals increased from 7.17 to 19.76% (90-170 °C for 30 min), which was 47.13 to 80.48% of that in DA-roasted SER meals, while no selenium was detected in the SER oils. Compared to DA roasting, VC roasting (90-170 °C for 30 min) reduced lipid oxidation products (LOPs), Maillard reaction products (MRPs), and benzo[a]pyrene contents, and increased carotenoids, unsaturated fatty acid contents, reaching a maximum oil yield of 35.58% at a lower temperature (130 °C for 30 min). Selenium contents exhibited a highly significant negative correlation with MRPs and LOPs (p ≤ 0.005). The VC roasting retarded selenium loss and improved SER oil quality compared to conventional DA roasting.

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.

Sustainable Extraction Methods Affect Metabolomics and Oxidative Stability of Myrtle Seed Oils Obtained from Myrtle Liqueur By-Products: An Electron Paramagnetic Resonance and Mass Spectrometry Approach

Myrtle liqueur production generates high amounts of by-products that can be employed for the extraction of bioactive compounds. Bio-based, non-toxic and biodegradable solvents (ethyl acetate and 2-methyltetrahydrofuran), and a mechanical extraction were applied to myrtle seeds, by-products of the liqueur production, to extract oils rich in phenolic compounds. The oils obtained were characterized for yield, peroxide value (PV), lipid composition, and total phenolic concentration (TPC). The phenolic profile of the oils, determined by LC-MS, the antioxidant activity, and the oxidative stability were also analyzed. A validated UHPLC-ESI-QTRAP-MS/MS analytical method in multiple reaction monitoring (MRM) mode was applied to quantify myricetin and its main derivatives in myrtle oils. The results pointed out clear differences among extraction methods on myricetin concentration. The oxidative stability of myrtle oils was studied with electron paramagnetic resonance (EPR) spectroscopy highlighting the effect of the extraction method on the oxidation status of the oils and the role of phenolic compounds in the evolution of radical species over time. A principal component analysis applied to LC-MS data highlighted strong differences among phenolic profiles of the oils and highlighted the role of myricetin in the oxidative stability of myrtle oils. Myrtle oil, obtained from the by-products of myrtle liqueur processing industry, extracted with sustainable and green methods might have potential application in food or cosmetic industries.

Non-Targeted Analytical Technology in Herbal Medicines: Applications, Challenges, and Perspectives

Herbal medicines (HMs) have been utilized to prevent and treat human ailments for thousands of years. Especially, HMs have recently played a crucial role in the treatment of COVID-19 in China. However, HMs are susceptible to various factors during harvesting, processing, and marketing, affecting their clinical efficacy. Therefore, it is necessary to conclude a rapid and effective method to study HMs so that they can be used in the clinical setting with maximum medicinal value. Non-targeted analytical technology is a reliable analytical method for studying HMs because of its unique advantages in analyzing unknown components. Based on the extensive literature, the paper summarizes the benefits, limitations, and applicability of non-targeted analytical technology. Moreover, the article describes the application of non-targeted analytical technology in HMs from four aspects: structure analysis, authentication, real-time monitoring, and quality assessment. Finally, the review has prospected the development trend and challenges of non-targeted analytical technology. It can assist HMs industry researchers and engineers select non-targeted analytical technology to analyze HMs' quality and authenticity.

Monitoring the lipid oxidation and flavor of Russian sturgeon fillets treated with low temperature vacuum heating: formation and relationship

BACKGROUND

Sturgeon is one of the most precious fish resources worldwide. Low temperature vacuum heating (LTVH) has been confirmed as a good way of maintaining food quality. However, there is a lack of in-depth studies assessing the impact of LTVH on lipid oxidation and flavor formation.

RESULTS

The present study compared the effect of LTVH and traditional cooking on lipid oxidation and flavor of sturgeon fillets. In total, 13 fatty acids were detected, of which polyunsaturated fatty acids content was the highest (P < 0.05). LTVH prevented the formation of conjugated diene and thiobarbituric acid reactive substances (P < 0.05), as manifested by an increased signal intensity of free radicals of electron spin resonance. The characteristic peaks intensity of lipid by Raman at 970 cm^-1 , 1080 cm^-1 and 1655 cm^-1 were reduced, whereas peaks at 1068 cm^-1 and 1125 cm^-1 displayed the opposite trend. Confocal fluorescence microscopy showed that the lipids particles were reduced and distributed more evenly with an increase in heating temperature. Principal component analysis of electronic nose cannot effectively separate all groups; however, gas chromatography-ion migration spectrometry showed that the volatile flavor compounds were relatively stable during LTVH. Correlation analysis of all the above lipid oxidation indices and characteristic flavor substances showed that each treatment group was located in different quadrants and demonstrated great differentiation.

CONCLUSION

Overall, the results of the present study support the view that LTVH is a healthier way of cooking. © 2022 Society of Chemical Industry.

Human dietary exposure to metals in the Niger delta region, Nigeria: Health risk assessment

The contamination profile and the human health risk assessment of various heavy metals (Cd, Cr, Mn, Ni and Pb) in vegetable oils, palm oils, butter and shea butter purchased from the Nigerian market were evaluated. Univariate and multivariate analyses including the principal component analysis (PCA), hierarchical cluster analysis (HCA) and heat map visualization were used to evaluate correlation, similarity and source of metals. Dietary intake and dermal absorption through the application in skin were also assessed. The heavy metals 5th and 95th percentile interval range (in mg/kg) were 0.003-0.208, 0.003-0.392, 0.003-1.344, 0.003-0.369 and 0.006-0.531 for Cd, Cr, Mn, Ni and Pb, respectively. Concentrations of Cr and Mn were significantly different across sample categories, being the levels of Mn and Ni positively correlated in both oil and butter samples. The result of PCA, HCA and heat map revealed the profile of heavy metals in oils was different from that of butters, with Pb mainly associated to oils, and Cd, Cr, Mn and Ni to butters. In some samples, the international maximum levels for Cd, Ni and Pb in edible oils were exceeded. Cadmium and Pb dietary intake through Nigerian oils and butters should not be considered negligible for human health protection.

Innovative and Sustainable Technologies to Enhance the Oxidative Stability of Vegetable Oils

To meet consumers’ demand for natural foods, edible oil producers and food processing industries are searching for alternatives to synthetic antioxidants to protect oils against oxidation. Antioxidant compounds extracted from different plant parts (e.g., flowers, leaves, roots, and seeds) or sourced from agri-food industries, including residues left after food processing, attract consumers for their health properties and natural origins. This review, starting from a literature research analysis, highlights the role of natural antioxidants in the protection of edible oils against oxidation, with an emphasis on the emerging and sustainable strategies to preserve oils against oxidative damage. Sustainability and health are the main concerns of food processing industries. In this context, the aim of this review is to highlight the emerging strategies for the enrichment of edible oils with biomolecules or extracts recovered from plant sources. The use of extracts obtained from vegetable wastes and by-products and the blending with oils extracted from various oil-bearing seeds is also pointed out as a sustainable approach. The safety concerns linked to the use of natural antioxidants for human health are also discussed. This review, using a multidisciplinary approach, provides an updated overview of the chemical, technological, sustainability, and safety aspects linked to oil protection.

Effect of oilseed roasting on the quality, flavor and safety of oil: A comprehensive review

Roasting is widely applied in oil processing and employs high temperatures (90-260 °C) to heat oilseeds evenly. Roasting improves the extraction yield of oil by the generation of pores in the oilseed cell walls, which facilitates the movement of oil from oilseed during subsequent extraction. It also affects the nutritional value and palatability of the prepared oil, which has attracted consumers' attention. An appropriate roasting process contributes to better extraction of bioactive compounds, particularly increasing the total polyphenol content in the oil. Correspondingly, extracted oil exhibits higher antioxidant capacity and oxidative stability after roasting the oilseeds due to better extraction of endogenous antioxidants and the generation of Maillard reaction products. Furthermore, roasting process is critical for the formation of aroma-active volatiles and the improvement of desired sensory characteristics, so it is indispensable for the production of fragrant oil. However, some harmful components are inevitably generated during roasting, including oxidation products, polycyclic aromatic hydrocarbons, and acrylamide. Monitoring and controlling the concentrations of harmful compounds in the oil during the roasting process is important. Therefore, this review updates how roasting affect the quality and safety of oils and provides useful insight into regulation of the roasting process based on bioactive compounds, sensory characteristics, and safety of oils. Further research is required to assess the nutritional value and safety of roasted oils in vivo and to develop a customized roasting process for various oilseeds to produce good-quality oils.

The loss and fate of BaA, Chr, BbF, and BaP (PAH4) tracked by stable isotope during frying

The objective of this work was to accurately quantify the loss of benzo(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(a)pyrene (PAH4) and investigate the fate of the lost PAH4 into their derivatives during frying. Stable isotopes (PAH4-d12) were used to simulate the loss and track the conversion of PAH4. The results showed that the rate of loss of PAH4-d12 increased with the increase of frying temperature and the loss rate of benzo(a)pyrene-d12 was the largest, indicating that benzo(a)pyrene had the strongest chemical reactivity during frying. Moreover, the identification of five PAH4 derivatives has confirmed the conversion of lost PAH4. Finally, the loss of PAH4 during frying positively correlated with the oxidation of oil, and a conversion mechanism of PAHs to derivatives was proposed. This work directly proved the loss and conversion of PAH4 and provided a comprehensive perspective for studying the changes in PAH4 during frying.

Effect of Multiple Freeze-Thaw Cycles on Lipid Degradation and Lipid Oxidation of Grass Carp Surimi Containing Different Amounts of Pork Back Fat

Fresh grass carp was used to produce surimi samples that were supplemented with 50 g/kg, 100 g/kg, or 150 g/kg pork back fat. The lipid composition, lipase activity, lipid oxidation index, and lipoxygenase activity of samples subjected to repeated freeze-thaw process were determined to assess the effects of the added fat on lipolysis and lipid oxidation of grass carp surimi. Freeze-thaw treatment increased free fatty acid content, mainly due to the decomposition of phospholipids and some neutral lipids by lipase. With repeated freeze-thaw treatment, the levels of free fatty acids and phospholipids were correlated with the lipid oxidation indexes and lipoxygenase activity, indicating that lipid degradation can promote lipid oxidation. In the same freeze-thaw cycle, surimi products with high fat content are more vulnerable to oxidative damage, neutral lipids are the main source of free fatty acids in the early stage of freeze-thaw, and phospholipids are the main source of free fatty acids in the late stage.

Edible Oil Parameters during Deterioration Processes

With the continuous increase in research on lipids, technologies and the development of chemical-analytical methods associated with the characterization and monitoring of different processes that involve modifications in edible fats are increasing. The beneficial effect of lipids, especially those essential for the health of the population, is widely known. However, degradation compounds are also produced that eventually have negative effects. In this dual context, the monitoring of the changes suffered by nutritional compounds can be obtained thanks to the development of technologies and analytical methods applied to the study of lipids. The modifications that lipids undergo can be followed by a wide variety of methods, ranging from the basic ones associated with simple chemical titrations to the more complex ones associated with sophisticated laboratory equipment. These determinations involve chemical and/or physical quantification of lipids to know an initial condition on the major and minor components. In addition to technologies that allow monitoring during more complex processes such as thermal deterioration, in multiple conditions depending on the objective of the study, this review could benefit a comprehensive understanding of lipid deterioration for future developments and research in the study of fats and oils for human consumption.

Impact of Tetrapeptide-FSEY on Oxidative and Physical Stability of Hazelnut Oil-In-Water Emulsion

This study investigates the antioxidant behaviors of a hazelnut tetrapeptide, FSEY (Phe-Ser-Glu-Tyr), in an oil-in-water emulsion. The emulsion was prepared with stripped hazelnut oil at a ratio of 10%. O/W emulsions, both with and without antioxidants (FSEY and TBHQ), were incubated at 37 °C. The chemical stabilities, including those of free radicals and primary and secondary oxidation productions, along with the physical stabilities, which include particle size, zeta-potential, color, pH, and ΔBS, were analyzed. Consequently, FSEY displayed excellent antioxidant behaviors in the test system by scavenging free lipid radicals. Both primary and secondary oxidation products were significantly lower in the FSEY groups. Furthermore, FSEY assisted in stabilizing the physical structure of the emulsion. This antioxidant could inhibit the increase in particle size, prevent the formation of creaming, and stabilize the original color and pH of the emulsion. Consequently, FSEY may be an effective antioxidant additive to use in emulsion systems.

Tracking Sensory Characteristics of Virgin Olive Oils During Storage: Interpretation of Their Changes from a Multiparametric Perspective

Virgin olive oil is inevitably subject to an oxidation process during storage that can affect its stability and quality due to off-flavors that develop before the oil surpasses its ‘best before’ date. Many parameters are involved in the oxidation process at moderate conditions. Therefore, a multiparametric study is necessary to establish a link between physico-chemical changes and sensory quality degradation in a real storage experiment. In this context, a storage experiment of 27 months was performed for four monovarietal virgin olive oils, bottled in transparent 500-mL PET bottles and subjected to conditions close to a supermarket scenario. Volatile composition, quality parameters and phenolic compounds were determined monthly. Simultaneously, an accredited sensory panel assessed their sensory characteristics. The stability of the fresh samples was also studied with the oxidative stability index (OSI) and mesh cell-FTIR. (E)-2-hexenal, (Z)-3-hexen-1-ol and (E)-2-hexen-1-ol were identified as markers of the fruity attribute. Hexanal and nonanal were also identified as compounds that were associated with the rise of median of defect during storage. Some disagreements were observed between the sensory assessment and the OSI analyzed by Rancimat. However, the increase of concentration of rancid markers agreed with the increase of aldehyde band measured with mesh cell-FTIR.