Oxidative Stability Of Oils Research Articles

Effects and mechanism of tea polyphenols on the quality of oil during frying process.

The effects and action mechanism of tea polyphenols (TP) on the quality of rapeseed oil during frying process were investigated. Results showed that compared with control, TP (0.04%, w/w) exhibited the remarkable ability to inhibit the deterioration of acid value, peroxide value, anisidine value, viscosity, and color of frying oil. By using gas chromatography-mass spectrometry, frying oil with TP showed the higher content of unsaturated fatty acids (72.79%) and lower content of trans fatty acids (3.36%) than those of control. Meanwhile, frying oil with TP had a higher total phenolic content than control at the same frying time. In addition, the thermo gravimetric-differential scanning calorimetry results showed that TP could increase the oxidation stability of rapeseed oil. Furthermore, according to the Fourier transform infrared and molecular dynamic simulation results, TP could reduce the breaking degree of = C-H bond, C-O-C bond, and C = C bond in oil molecules, and inhibit the oxidation of oil components by inhibiting the generation of free radicals and eliminating free radicals. All present results suggested that TP showed the potential value to be used for protecting the quality of oil during the frying process in food and chemical industries. PRACTICAL APPLICATIONS: The inhibitory effect of tea polyphenols on the deterioration of quality of rapeseed oil during frying was found and the mechanism had also preliminarily interpretation. This work provided a method for monitoring the quality of fry oil and provided the theoretical basis for the use of tea polyphenols in frying.

Pickering emulsions stabilized by luteolin micro-nano particles to improve the oxidative stability of pine nut oil.

Pine oil contains a high percentage of polyunsaturated fatty acids, which make it prone to oxidation. Luteolin (LUT) micro-nano particles with antioxidant properties can be used as stabilizers to form an edible oil-in-water Pickering emulsion to improve the oxidative stability of pine nut oil. Under optimal preparation conditions, the LUT micro-nano particles and pine nut oil account for about 0.44 and 90.9 g·kg-1 of the total mass of the emulsion, respectively. The LUT particles in the suspension have a mean particle size of about 479 nm, present a sheet-like structure with a cut surface of 30-50 nm, and can reduce the surface tension of deionized water. In the optimized Pickering emulsion, the emulsion droplets are approximately spherical and have a mean diameter of about 125.6 nm and uniform distribution. The optimized Pickering emulsion droplets can remain stable for up to 2 h in an environment where the pH levels are 7-8.5, ultraviolet B radiation (UVB) irradiation, of less than 5.0 g·kg-1 , and at a temperature of 80 °C. The stability of the emulsion in simulated digestive fluid changed minimally. In the first 7 days of the accelerated oxidation experiment, LUT micro-nano particles not only successfully protected the integrity of emulsion droplets but also fully inhibited the peroxidation of pine oil. The strong antioxidant properties of LUT micro-nano particles, and the dense protective layer they formed, stabilized the Pickering emulsion successfully. The particles also improved the oxidation stability of pine nut oil. © 2020 Society of Chemical Industry.

Prediction of Walnut Deterioration Using Kernel Oxidative Stability.

Monitoring walnut oxidation is essential to control walnut quality during storage. An accelerated oxidation method for differentiating the oxidative stability index (OSI) of walnut kernels was examined and the effects of instrument operational parameters such as temperature and airflow were evaluated. Four cultivars, Chandler, Solano, Durham, and Howard were analyzed at 110, 120, and 130 °C with 15, 20, and 25 L h−1 airflow. Analysis using 110 °C with 25 L h−1 yielded the lowest coefficients of variance (4.4) than other operational parameters; analysis using the same temperature at lower airflow, 15 L h−1, yield the highest coefficient of variance (10.5). Kernel OSI values were independent of airflow, however, dependence of temperature coefficient and Q10 were demonstrated. The results from selected parameters were correlated with fat and moisture content, peroxide value, UV absorbances, oil oxidative stability, hexanal, and rancidity to establish the relationships between OSI values and quality changes during storage. Using 0.5 g of ground kernels, at 110 °C with 25 L h−1 airflow gave a lower coefficient of variance and higher correlation with kernel quality and oxidative markers comparing to other combinations of operating parameters.

Effect of Star Anise as a Natural Antioxidant Additive on the Oxidation Stability of Lemon Grass Oil

Oxidation of biodiesel leads to its degradation and reduces its market value. The oxidation stability of lemongrass oil produced through the steam distillation process can be improved by means of star anise antioxidant addition. Star anise antioxidant was converted into fine powder through ball milling. The morphology of antioxidant has been analyzed by scanning electron microscopy, and elemental composition by Energy Dispersive Spectrum and Carbon, Hydrogen, Nitrogen, and Sulphur analysis. The presence of antioxidant promoting components was revealed by means of Fourier Transform Infrared Spectroscopy. The effect of temperature on antioxidant particles has been carried out using Differential Scanning Calorimetry and Thermogravimetric Analysis. The scavenging ability of the star anise antioxidant was evaluated by DPPH assay (%) at various concentrations (500, 1000, and 1500 ppm) and found to be 80.67, 81.38, and 81.73 respectively. The total phenolic content was evaluated through the Folin–Ciocalteu method and calculated to be 134.2 Gallic Acid Equivalent mg/g. The oxidation stability in terms of induction period was evaluated through the accelerated oxidation test called Rancimat method. The addition of antioxidant increased the IP from 2.50 to 19.79 h at 1500 ppm. Thus the addition of antioxidant enhanced the storage stability of LGO and thereby improving its market value.

Motor oil degradation during urban cycle road tests

Several civilian vehicles in China operate in urban traffic conditions and have their motor oil changed every 5,000 km. This study investigates the variations in oil properties after servicing at 5,000 km, based on systematic road tests (including a repeated test, a parallel test, and a new vehicle test). The physicochemical properties, changes in components, oxidation stability, detergent-dispersant performance, and tribological properties of motor oils were analyzed. The results showed that the total acid number (TAN) of oils increased with the operation mileage, by up to 1.41 mgKOH/g. The total base number (TBN) decreased after the road tests were completed, and the decrease was less than 44.6%. The kinematic viscosity (KV) of most oils decreased initially and then stabilized in the middle stage, before starting to increase later in the experiment. The change in KV at 100 °C was less than 15.96%. The oxidation onset temperature (OOT) of the oils diminished gradually with the operation mileage. All OOT values of the used oils were higher than 210 °C. A spot test indicated that the used oils retained their detergent-dispersant performance to an appropriate extent. The four-ball wear scar diameters and friction coefficient of the used oils did not increase significantly after the road tests were completed. This study can serve as a reference for end-users when changing motor oils.

Free Radical Scavenging Activity of Some Legumes Hulls Extract and Its Efficacy on Oil Oxidative Stability.

Synthetic antioxidants have toxigenic effects, there is therefore growing interest in substituting them with natural antioxidants. Attention is being focused on extracting them from agricultural industry residuals to minimize costs. Legume seed hulls could be cheap sources of such natural antioxidants. This study aims to unravel potential free radical scavenging activity, antioxidant activity, and total phenolic and flavonoid contents of some legumes' hulls extracted by different solvents and evaluate their efficacy to enhance sunflower oil stability. Legume hulls extracted by different solvents were evaluated for their antioxidant activity coefficient (AAC), free radical scavenging activity [by 2,2-diphenyl-1- picrylhydrazyl (DPPH)], and phenolic and flavonoids contents. The protection factor and induction periods (rancimat test) of the highest activity extracts were evaluated. Sunflower seed hull ethyl acetate extract, lupine seed hull ethanol extract, and mung bean hull petroleum ether extract exhibited stronger DPPH scavenging activity, AAC, and protection factor values than other solvents. Ethyl acetate extracts of sunflower seed hulls showed an antioxidant and scavenging activity close (P>0.05) to that detected for α-tocopherol. Legume hulls may possess strong free radical scavenging and antioxidant activity. The analogous effect between sunflower hull extract and α-tocopherol make it a potential, cheaper substitute of α-tocopherol in food systems. The analogous effect between sunflower hull extract and α-tocopherol give it the potency to allow substitution at a concentration of 0.5% of sunflower hull ethyl acetate or 1% of lupine hull ethanol extract instead of 0.5% α-tocopherol to enhance induction periods and protection factors of sunflower oil.

Plum ( Prunus domestica L.) leaves extract as a natural antioxidant: Extraction process optimization and sunflower oil oxidative stability evaluation

The current work aimed to maximize the yield of total phenolic content (TPC) and associated antioxidant activity of plum leaf extract. The feasibility of using the optimal extract as a natural antioxidant for retarding the oxidation process in sunflower oil using rancimat method was also investigated. One-factor-at-a-time (OFAT) method and 32 full factorial design were implemented in sequence to optimize the studied factors (extraction time [ET] (10–60 min) and ethanol percentage [EtOH%] (0%–75%)). DPPH scavenging ability of the obtained extracts were positively (r ≥ 0.7493) and significantly (p < .0001) correlated to TPC yield. The optimal conditions for extraction plum leaves were 64.37% EtOH% and 60 min with desirability of 0.856. The optimal plum leaves extract was subjected to HPLC analysis. At the same concentration (200 ppm), the protection factor of BHT and optimal plum leaves extract against sunflower oxidation were insignificantly (p > .05) differed. Practical applications Plum (Prunus domestica L.) leaves are characterized by a high content of phenolic compounds which varied between 66.50 to 143.7 mg GAE/g powder. Plum leaf extracts exhibited high scavenging activity against DPPH radicals. The protection factor of the freeze-dried optimal leaves extract was insignificantly differed than that of BHT at the concentration of 200 ppm. These findings indicate that plum leaves extract could efficiently retard the oxidation process of edible oils; and consequently, improve their quality and extend their shelf life.

Extraction of pumpkin peel extract using supercritical CO2 and subcritical water technology: Enhancing oxidative stability of canola oil

In this study, subcritical water extraction (SWE) and the supercritical fluid extraction (SFE) methods were used for the extraction of pumpkin peel extract. Total phenolic content and carotenoid compounds of extracts were measured. The extracts were added to canola oil at a concentration of 400 ppm and were stored at 30 °C for 60 days. The peroxide, carbonyl and acid values of the oil samples were measured, then compared with 100 ppm of tert-butylhydroquinone (TBHQ) synthetic antioxidants. The results showed that the total phenol content of obtained extract by SFE (353.5 mg GA/100 g extract) was higher than by SWE (213.6 mg GA/100 g extract), while the carotenoid content was higher for obtained extract by SWE (15.22 mg/100 g extract) compared to SFE (11.48 mg/100 g extract). The result of oil oxidation showed that the oxidative stability of the oil containing the mixed extract (SFE–SWE) is higher than the separate extract, consequently showing higher performance in preventing oil oxidation compared to TBHQ.

Extraction and Characterization of Polyphenols from Artocarpus heterophyllus and Its Effect on Oxidative Stability of Peanut Oil

ABSTRACT The present study deals with the extraction and characterization of Jackfruit seed polyphenol (JSP) and its application in the stabilization of peanut oil. The optimized extract was obtained at condition of 95% ethanol for 30 min by using conventional solvent extraction method. The extract exhibited a total phenolic content of 120.5 µg GAE/mL, flavonoid content of 0.43 mg CE/ml, condensed tannin content of 0.34 mg CE/ml and DPPH scavenging EC50 value of 14.22 µg/ml. The characterization of extract by LC-ESI-Q-TOF-MS/MS revealed the presence of phenolic acid, flavonoids, and stilbenes. The JSP extract in the presence of synthetic antioxidants such as butylated hydroxytoluene (BHT) and α-Tocopherol-acetate (vitamin-E acetate) were tested for the stabilization of cold-pressed peanut oil. Furthermore, natural antioxidant mediated stabilization of cold-pressed peanut oil was also investigated using α-Tocopherol (vitamin E) and curcumin. The JSP extract and curcumin significantly retarded lipid oxidation in peanut oil under Schaal oven test conditions of 60°C for a week, as compared to BHT, α-Tocopherol, and α-Tocopherol acetate. Also, the JSP extract and curcumin showed better antioxidant effects on the oxidative stability of oil at frying temperature of 150–180°C for 2 hr and thus can prove potential in ensuring the retardation of oil oxidation process. Hence, JSP extract and curcumin can have industrial application of serving as a natural preservative in oil.

Analysis of Reaction Kinetics of Edible Oil Oxidation at Ambient Temperature by FTIR Spectroscopy

AbstractEdible oils are studied to analyze their reaction kinetics during oxidation and predict shelf life at ambient temperature. Rapeseed oil (RO), soybean oil (SO), linseed oil (LO), and peanut oil (PO) are detected via Fourier transform infrared spectroscopy with a mesh cell as spectral acquisition accessory. The reaction kinetics of ROOH bonds, C═O bonds, trans double bonds (TDBs), and carbon chain skeletons (CCSs) are determined by absorbance changes in their characteristic absorption peaks. Prediction models for shelf life based on various characteristic absorption peaks are converted via the reaction kinetics equations of the oils. Results show that first‐order reaction kinetics are used to describe absorbance changes of ROOH bonds in PO, SO, and LO, while zero‐order reaction kinetics are used to describe the absorbance changes in RO. Both C═O bonds and CCS absorbance changes in the four oils satisfy first‐order reaction kinetics. TDBs absorbance changes in PO, SO, and LO are in accordance with zero‐order reaction kinetics. The regression equations of reaction kinetics exhibit good fitting degree (coefficient of determination, R2 &gt; 0.9000) and statistical significance (p &lt; 0.001), indicating that the proposed method can be used to analyze the reaction kinetics of oil oxidation and predict shelf life.Practical Applications: The reaction kinetics of RO, SO, LO, and PO are studied at ambient temperature and the shelf life is predicted by using FTIR spectroscopy based on the absorbance changes of ROOH bonds, C═O bonds, TDB bonds, and CCS in the oils. The shelf life of edible oils can be more effectively predicted in this case and provide a practical reference for food industries. Furthermore, the proposed technique is rapid, green, and accurate, and allows real‐time characterization of absorbance changes in various characteristic absorption peaks, which corresponded to different oxidation products. By this method, it is possible to reflect real‐time information for different quality indices (such as peroxides and acid values) of oil oxidation simultaneously, and unnecessary to measure these indices directly one by one, saving manpower and material resources. Therefore, FTIR spectroscopy is convenient for the rapid evaluation of oxidation stability and shelf life of edible oils under ambient temperature.

Effects of Fe(III) and Fe(II) on the peroxidation value of soybean oil under different conditions and product characterization

Presence of iron, oil oxidizes, and deteriorates. In this paper, the effects of Fe(III) and Fe(II) with different storage conditions on oxidation stability of soybean oil were studied. To further clarify the reactions, emphatically, the chemical structure of the oil and sediment was characterized. The results showed that the peroxide value (PV) of soybean oil decreased with the increase of Fe(III) dosage, whereas Fe(II) did not. A rise in temperature would cause PV increase of all samples. Comparing with the blank group, Fe(II) and Fe(III) could promote and inhibit the oxidation of soybean oil, respectively, and PV of the vacuum-treated samples remained unchanged. When both Fe(III) and Fe(II) existed, the higher the proportion of Fe(III), the lower PV. There was no significant change in soybean oil and Fe(II) after the reaction. However, Fe(III) was wrapped in soybean oil due to chemisorption, which cannot be washed by conventional methods. Practical applications This study shows that Fe(II) can promote the peroxide value of soybean oil to increase, and Fe(III) can not only decompose the peroxide but also have chemical adsorption on the peroxide after reaching a certain amount of addition. Therefore, Fe(III) can be utilized to the adsorption of peroxide to reduce the peroxide value. It has a definite guiding significance for the application of waste oil in industry and the storage of edible oil.

Soy Protein Isolate Films Incorporated with Pinhão (Araucaria angustifolia (Bertol.) Kuntze) Extract for Potential Use as Edible Oil Active Packaging

One of the traditional residues obtained from pinhao seeds (Araucaria angustifolia (Bertol.) Kuntze) consists of an aqueous extract produced from the cooking process, which presents a significant concentration of phenolic compounds with antioxidant properties. In this work, soy protein isolate (SPI) films with different concentrations of pinhao cooking water extract (EP, 0.5, 1, and 2% wt/wt) were produced and physical properties, microstructure, and antioxidant capacity were investigated. The films were applied as packaging (as sachet-type) for linseed oil, and the oil oxidative stability was evaluated during 10 days under accelerated storage condition (60 °C) by conventional procedures (peroxide index, specific extinction coefficient, and UV-Vis spectrophotometry) and by multivariate curve resolution with alternating least squares (MCR-ALS) chemometric method. The film with EP contributed to the oxidative stability of linseed oil being an interesting alternative of active biodegradable packaging for edible oils.

Influence of heated, unheated whey protein isolate and its combination with modified starch on improvement of encapsulated pomegranate seed oil oxidative stability

This study aimed at encapsulating pomegranate seed oil (PSO) by emulsification followed by spray drying using whey protein isolate (WPI) in its natural form, heated (Pickering), and combined with modified starch (WPI:Capsul®) as emulsifiers/wall materials. Emulsions were stable under different stress conditions. Pickering emulsions presented bigger droplet size (6.49–9.98 μm) when compared to WPI (1.88–4.62 μm) and WPI:Capsul® emulsions (1.68–5.62 μm). Sixteen fatty acids were identified in PSO. WPI treatment was considered the best formulation since it presented the highest fatty acid retention (68.51, 65.47, 47.27, 53.68, 52.95, and 52.28% for linoleic, oleic, punicic, α-eleostearic, catalpic, and β-eleostearic acids after 30 days-storage, respectively) and protected the oil against volatile compound formation (heptanal, (E,E)-2,4-heptadienal, (Z)-2-heptenal, octanal, pentanal, (E)-2-hexenal, (E)-2-octenal, nonanal, (E)-2-decenal, and (E,E)-2,4-octadienal), which did not occur with free PSO. Overall, encapsulation protected PSO against oxidation over time, which may allow the development of new functional foods.

Incorporation of the nanoencapsulated polyphenolic extract of Ferula persica into soybean oil: Assessment of oil oxidative stability.

In the present study, for the first time, the biological activities of Ferula persica extract (FPE) coated with locust bean gum (LBG) and chitosan in W/O/W emulsions were investigated. Based on the findings, the Z‐average size of emulsions coated by chitosan, LBG, and the complex of chitosan and LBG (1:1) (CCL) was 115.47, 128.37, and 68.12 nm, respectively. The encapsulation efficiency of the phenolic extracts in the powder produced by chitosan, LBG, and CCL decreased from 85.3 to 64.1, from 89 to 71.4, and from 93.3% to 77.9% during 24‐day storage, respectively. Also, the application of the coating in the encapsulation of FPE increased the antioxidant efficacy in soybean oil while compared with tert‐butylhydroquinone (TBHQ) and un‐encapsulated FPE. In this regard, The FPE nanoencapsulated by CCL showed the best antioxidative activity in soybean oil, followed by the FPE of nanoencapsulated by LBG and chitosan, respectively, which can be correlated with higher levels of polyphenolic compounds release over time in the sample coated with CCL. In this context, the encapsulation with CCL can be proposed as a promising technique to improve the antioxidant activity of extracts.

Impact of linolenic acid on oxidative stability of rapeseed oils.

The objective of this study was to investigate the effects of linolenic acid (LA) on oxidation stability of rapeseed oils. Four kinds of rapeseed were harvested by unified cultivation and management in the same geographical conditions, and then four rapeseed oils with different contents of LA were obtained. The effects of linolenic acid and antioxidants (tocopherols and phytosterols) on oxidation stability of rapeseed oils were evaluated. Results showed that rapeseed oil with 5.9% LA was the most stable among four rapeseed oils, followed by commercial rapeseed oil, rapeseed oil with 8.4% LA and rapeseed oil with 10.8% LA. The oxidation stability was negatively correlated with the contents of LA (r = - 0.931, p < 0.01), the polyunsaturated fatty acids (r = - 0.932, p < 0.01), and unsaturated fatty acids (r = - 0.766, p < 0.05). It had no correlation with tocopherols and phytosterols (p > 0.05). In addition, according to the European Union Standards, shelf-life of four rapeseed oils was longer than 30days in the shelf-life test. Therefore, increasing the LA content in rapeseed oils can be considered as an efficient approach to solve the problem of insufficient LA intake globally.

Preparation and Characterization of a Polar Milk Lipid-enriched Component from Whey Powder.

Milk fat globule membrane (MFGM) is a lipid carrier in mammals including humans that consists mainly of polar lipids, like phospholipids and glycolipids. In this study, a process to enrich polar lipids in commercial butter and whey powder, including polar lipids of MFGM, was developed. WPC (whey protein concentrate) 60 was selected as the most suitable raw material based on the yield, phospholipid, protein, and lactose content of the polar lipid fraction obtained by ethanol extraction of two WPC (WPC60 and WPC70) and two buttermilk (A and B). After fractionation under optimum conditions, the polar-lipid enriched fraction from WPC60 contained 38.56% phospholipids. The content of glycolipids, cerebroside, lactosylceramide, ganglioside GM3, ganglioside GD3, was 0.97%, 0.55%, 0.09%, and 0.14%, respectively. Rancimat results showed that the oxidation stability of fish oil increased with an increase in the polar-lipid fraction by more than 30 times. In addition, the secretion of IL-6 and TNF-α decreased in a concentration-dependent manner after treatment of RAW 264.7 cells with 0.1 to 100 ppm of the polar lipid fraction. In this study, polar lipid concentrates with antioxidant and anti-inflammatory activity, were prepared from milk processing by-products. The MFGM polar lipid concentrates made from by-products are not only additives for infants, but are also likely to be used as antioxidants in cooking oils and as active ingredients for functional foods.

Change in some quality parameters and oxidative stability of olive oils with regard to ultrasound pretreatment, depitting and water addition

Ultrasound pretreatment with different times (0, 4, 8, 10 min) on olive paste previous malaxation of olive oil extraction along with depitting and water application procedures were studied. The effects of these procedures on oil yield, quality parameters and oxidative stability have been studied. Therefore, the olive oil yield increase with increasing time of ultrasound treatment. On the other hand, the application of ultrasound did not adversely affect the quality characteristics, as well as the antioxidant activity, when comparing with untreated paste. Furthermore, the oxidative stability data, we can conclude that ultrasound treatment can affect the olive oil oxidative stability. This study could provide useful information for industry to produce olive oil with high yield and quality.

Effect of Star Fruit (Averrhoa carambola L.)By-product on Oxidative Stability of Sesame (Sesamum indicum) Oil under Accelerated Oven Storage and during Frying.

Aim of this study was to evaluate the effect of star fruit (Averrhoa carambola L.) by-products (peel and residue) on stability of sesame (Sesamum indicum) oil against oxidation. Antioxidant properties of extract of peel and residue at different time durations of extraction were determined and found that peel contains higher antioxidant potential than residue. Thus, extract of peel obtained after 24 h extraction was used to study its effectiveness on oxidative stability of sesame oil during accelerated oven storage and frying using the butylated hydroxytoluene (BHT) (200 ppm) as the reference antioxidant (positive control) and oil without added antioxidant as the negative control. The oxidative stability of the oil was determined by evaluating peroxide value, p-anisidine value, thiobarbituric acid reactive substances (TBARS) value, total oxidation (TOTOX) value, conjugated diene (CD) and conjugated triene (CT) values, and iodine value. Peel extract at different concentrations (200-1000 ppm) was tested. The oil added with peel extract exhibited higher stability against oxidation than the controls during oven storage test. Extract at 1000 ppm significantly increased the stability of sesame oil during frying as compared with controls. Thus, star fruit peel extract could be an alternative to synthetic antioxidants to suppress oxidation of edible oils.

Effect of Extraction Methods on Quality Characteristics of Chia Seed Oil

Chia seed oil was extracted from Chia seeds by pressing method,solvent extraction method,water enzymatic method and supercritical CO2 extraction method. The physicochemical properties,fatty acid composition,quality characteristics such as oxidative stability of oils,phenolic substances and antioxidant capacity in vitro of Chia seed oil were extracted by different methods. The results showed that among the four methods,the supercritical CO2 extraction method had the highest oil yield(85.5%),followed by the solvent extraction method(65.8%)and the pressing method(40.9%),and the lowest water enzymatic method(33.2%). The supercritical CO2 extraction of Chia seed oil had the best quality,the color was Y70R4.3N0.3,the acid value was 1.10 mg KOH/g,the peroxide value was 0.0137 g/100 g,and the total mass fraction of unsaturated fatty acids was 88.22%. Linoleic acid content was 18.36%,linolenic acid content was 69.86%,The oxidation rate was the slowest after 30 h,and the peroxide value reached 0.25 g/100 g,the total phenol content was 106.45 mg/kg,and the flavonoid content was 222.09 mg/kg. Supercritical CO2 extraction of Chia seed oil at the same concentration of DPPH free radical scavenging capacity(IC50 28.04 mg/mL)and ABTS+· scavenging capacity(IC50 33.70 mg/mL)was superior to pressing,solvent extraction and the water enzymatic method,the superoxide anion radical scavenging ability(IC50 10.08 mg/mL)was superior to the solvent extraction method and the water enzymatic method,which was slightly lower than the pressing method.

Antioxidant activity of citron peel (Citrus medica L.) essential oil and extract on stabilization of sunflower oil

Due to the unfavorable effects of synthetic antioxidants, the use of various sources of plant antioxidants to prevent foods oxidation, especially oil-based or fat-based varieties, has been recently got considerable attention. In this study, the antioxidant effect of essential oil and extract from the citron fruit (Citrus medica L.) was investigated on the thermal stability of sunflower oil. Aqueous, ethanolic, and methanolic extracts of citron peel (800 ppm), BHT synthetic antioxidant (200 ppm), and citron peel essential oil (800 ppm) were added to sunflower oil. The oil oxidation stability was evaluated during 5 days through analyzing the values of peroxide, anisidine, thiobarbituric acid, totox, and oxidative stability index (OSI). Results showed that the peroxide, anisidine, and totox value had an increasing trend over time. The effects of storage time, extract, and essential oil were statistically significant in reducing the oxidation rate of sunflower oil during storage. Ultrasonic-assisted ethanolic extract at 30 min showed the highest OSI. The results of this study demonstrated the positive effects of citron peel extract essential oil and on sunflower oil stability and its superiority over synthetic antioxidants.