Measuring Peroxide Value Research Articles

Effect of initial quality of oil and thermal processing on oxidation indexes in canned tuna

The content of fatty acids and the ratio of unsaturated and saturated fatty acids are essential parameters for determining the nutritional value of oils. The main objective of this study was to identify the oxidation changes of three vegetable oils (soybean, sunflower, and olive oil) at two qualitative levels in the canned tuna product before and after the thermal process. The progress of oil oxidation was assessed by measuring peroxide value (PV), p-anisidine value (AV), malonaldehyde (MDA) content, Conjugated dienes (CDs), and conjugated trienes (CTs), p-anisidine value, total free acidity, INTOX and TOTOX values. The results indicated that the quality of oil extracted from canned fish changes according to the type of oil (p < 0.01). A decrease in the peroxide value during the thermal process (<2 meq O2/kg oil in olive and soybean oil), indicated that this parameter is not suitable for showing product quality and oxidation progress, lonely. Secondary products of oxidation, in soybean oil under sterilization caused an increase of p-anisidine value (149) but in olive and sunflower oil heating caused a rise of MDA content. Acidity value was an index that increased after heating all types of oil and all types of quality and seemed to be more reliable for determination of the quality of oil in canned tuna (p < 0.01).

The prooxidant effect of natural antioxidants combination when co‐encapsulated to chia oil‐based nutraceutical edible powders: More is not always better

AbstractChia oil (CO) is the vegetable source with the highest ω − 3 polyunsaturated fatty acids (PUFAs) proportion known to date (61%–70%). Although this is favorable from a nutritional point of view, higher contents of ω − 3 PUFAs result in shorter shelf life and poorer oxidative stability. The objective of this work was to design edible oil powders of CO co‐encapsulated with commercial antioxidant‐rich sources—containing β‐carotene (BC), astaxanthin (ASX), and vitamin E (VE), either alone or combined (BC–VE and ASX–VE)—to prolong its oxidative stability. To carry out this, spray‐dried microcapsules were produced through oil‐in‐water double‐layered emulsions using whey proteins and pectin. Spray‐dried capsules were stored at 4 and 30°C, and weekly determinations of primary and secondary oxidation compounds were carried out, by measuring peroxide value (PV) and thiobarbituric reactive substances. CO microcapsules with just one commercial antioxidant‐rich source played a key role to keep oxidative indicators below recommended limits (PV &lt; 15 meq kg−1 oil) when storing powders at 30°C, being ASX the best option, whereas there was no significant effect in oxidation when stored at 4°C. Nevertheless, when combining commercial antioxidant sources (BC–VE and ASX–VE), a marked prooxidant effect was observed, exceeding PV threshold at both temperatures after 2 months of storage.Practical Applications: Combination of chia oil and natural antioxidant commercial sources in edible powders constitutes a promising commodity to design potentially anti‐inflammatory nutritional interventions to prevent chronic noncommunicable diseases. This study contributes to show that mixing different antioxidants with chia oil might have a detrimental effect on oil oxidative stability during storage, so caution must be applied when formulating this type of functional ingredients as more is not always better. The goal of this contribution is that it was possible to obtain an easy‐to‐handle powder nutraceutical ingredient containing both chia oil and astaxanthin (using antioxidant concentrations that might have a significant effect on human health) that could be stored at 30°C up to 8 weeks, keeping oxidative indicators below the limits recommended by Codex Alimentarius (peroxide value &lt;15 meq kg−1 oil).

Microencapsulated polyphenol extracts from Georgia-grown pomegranate peels delay lipid oxidation in salad dressing during accelerated and ambient storage conditions.

Lipid oxidation is a major cause of quality deterioration in salad dressings. This study evaluated the effect of incorporating microencapsulated polyphenol extracts via spray drying from pomegranate peels (MPP) to delay lipid oxidation in Italian-style salad dressings (ISD) during accelerated (55°C) and ambient (25°C) storage conditions. ISDs, prepared at high (5000 rpm) and low (250 rpm) shear rates conditions, were formulated with unencapsulated polyphenol extracts from pomegranate peels (PPP), MPP, and/or grape seed extract (GSE). Lipid oxidation in ISDs was evaluated by measuring peroxide value (PV), iodine value (IV), and TBARS, stored in accelerated and ambient conditions for 21 days and 8 weeks, respectively. Tannis in extracts were measured via HPLC-DAD and the total hydrolyzable tannin content of PPP and MPP was 283.09 and 427.74 (mg/g extract), respectively. Condensed tannins were not detected in PPP and MPP but were found in GSE (348.53 mg/g extract). Salad dressings prepared at high shear rates had significantly (p < .05) higher emulsion stability than those homogenized at low shear rates. Mixing conditions did not affect the lipid oxidative stability of IDSs. Salad dressing stored under accelerated storage had higher lipid oxidation (higher PV, lower IV, and higher TBARS) after 21 days than IDSs stored under ambient conditions for 8 weeks. ISDs prepared with MPPP showed significantly (p < .05) lower lipid oxidation than the other ISDs at the end of the shelf life studies. Results from the accelerated storage suggested that incorporating MPP could have extended the shelf life of IDSs by 20% compared to using unencapsulated polyphenol extracts. The study demonstrated that MPP delays lipid oxidation in ISDs during storage more effectively than unencapsulated extracts. MPP may serve as a natural and effective functional food ingredient for controlling lipid oxidation in high-lipid and acidified foods.

Synthesis of lipoic acid ferulate and evaluation of its ability to preserve fish oil from oxidation during accelerated storage.

Lipoic acid ferulate (LAF) was synthesized and its anti-free radical ability in vitro was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS) assays. Protective effects of LAF in stabilizing fish oil were tested, compared to antioxidants such as lipoic acid, ferulic acid and tert-butylhydroxyquinone (TBHQ) by measuring peroxide values, thiobarbituric acid reactants, p-anisidine values, nuclear magnetic resonance (NMR) spectra and gas chromatography-mass spectrometry (GC-MS) spectra of fish oil during accelerated storage (12days, 80°C). The inhibitory effect of these antioxidants on fish oil oxidation followed the order TBHQ ≧ LAF>ferulic acid>lipoic acid. In addition, the omega-3 polyunsaturated fatty acids were the first to be oxidized. The formation of oxidation products followed a first-order kinetic model, and the addition of LAF effectively reduced the reaction rate constants. Therefore, LAF can effectively slow down the formation of oxidative products and prolong the shelf life of fish oil.

Determination of eicosapentaenoic acid and docosahexaenoic acid contents and the oxidation level of fish oil supplements from Bahrain market

Eicosapentaenoic acid and docosahexaenoic acid are two types of omega-3 fatty acids that provide numerous health benefits. It is thus important to gain the recommended daily intake of eicosapentaenoic acid and docosahexaenoic acid and compensate for omega-3 deficiency through supplements. However, supplements are very susceptible to oxidation, which affects their biological significance. This study aimed to examine the quality of fourteen different commercially available fish oil supplements in Bahrain markets by comparing their actual and labelled Eicosapentaenoic acid and docosahexaenoic acid contents, determination of their oxidation levels by measuring the peroxide value, anisidine value, and the total oxidation value. Fish oils were methylated, separated, and identified by Gas Chromatography. Measurement of peroxide value was conducted using titration, and the anisidine value using spectrophotometry. The total oxidation value was calculated based on anisidine value and peroxide value values. Results showed that most brands have lower actual total fish oil per capsule than the labelled values. Only two brands (14.29%) showed an approximately similar amount of Eicosapentaenoic acid and docosahexaenoic acid, whereas six brands (42.86%) have a lower actual amount of both Eicosapentaenoic acid and docosahexaenoic acid. In addition, five brands (35.71%) have higher actual EPA and lower DHA values. Only one brand has higher actual amounts of both Eicosapentaenoic acid and docosahexaenoic acid. The results also showed that 57.1% of the tested supplements (8 out of 14) exceeded the recommended levels of peroxide value, while only one brand (7.14%) exceeded the safe levels of anisidine value. Moreover, five brands (35.71%) recorded a total oxidation value level higher than the recommended. Compared to other studies in several countries, the oxidative levels of supplements in Bahrain are not very high; nonetheless, it must be improved by applying oxidation levels regulations and storage regulations regarding fish oil supplements.

CHANGES IN THE PEROXIDE NUMBER AND THERMAL OXIDATION PRODUCTS IN DEEP-FRYING FATS IN THE PRODUCTION OF SNACK PRODUCTS

The quality of frying fat is important in the production of snack products. High temperature, oxygen, water spoil the fat. The stability of frying fat is very important for manufacturers.&#x0D; Botanical extracts (natural antioxidants) are preferred by humans, maintain an attractive clean label, extend the life of the deep fryer before replacing it, extend the shelf life of the product. In the course of the research, the possibility of a significant extension of the period of use of frying fats with the addition of antioxidants “Extrale” was confirmed, effective parameters for monitoring the quality of frying fats were identified and&#x0D; substantiated.&#x0D; In the test, a natural extract of rosemary was used, as well as food additives complex “Extrale RT” and “Extrale GT” produced by the Republic of Belarus. Using the synergism of rosemary extract, green tea extract and a mixture of tocopherols, Belagrolex specialists managed to create new and very effective antioxidants.&#x0D; Based on our research experience, the introduce the measurement of peroxide value and express methods for controlling the content of oxidized substances for quality control of frying fat is recommended. The control of these parameters will significantly improve the quality of snack products, and the use of Ektrale antioxidants will extend their shelf life and the time of using frying fat.

Effects of the BHA and basil essential oil on nutritional, chemical, and sensory characteristics of sunflower oil and sardine (Sardina pilchardus) fillets during repeated deep-frying

This study was to evaluate the BHA and basil essential oil on the quality attributes of deep-fried sardine fillets and frying oil. The extent of lipid oxidation was monitored by measuring peroxide value (PV), thiobarbituric acid reactive substances (TBARS), TBA, and changes in free fatty acids. Sensory analysis and color values upon the frying period were also determined. PV, FFA, TBA, and TBARS values in fish fillets and frying oil have peaked and then decreased at the end of frying except for the control. BEO showed the highest sensory scores compared to others. As a result, it is not possible to make a clear judgment about the effect of the natural or synthetic antioxidants on all lipid oxidation products that may occur during frying both fish fillets and frying oil. This study suggests that secondary oxidation products in frying oil and the sensorial quality of fish fillets can be better controlled by using basil essential oil.

Green Tea Extract Enhances the Oxidative Stability of DHA-Rich Oil.

Docosahexaenoic acid (DHA) is one of the most important omega-3 polyunsaturated fatty acids, with proven health-promoting properties. However, oils with a very high content in DHA (DHAO) are extremely susceptible to oxidation, which affects shelf stability and limits incorporation in food products. Green tea extracts (GTE) are potential candidates for the protection of these oils, but their use in such oils has not been previously reported. This study investigated the effect of GTE (160 ppm, 400 ppm, 1000 ppm) and α-tocopherol (80 ppm, 200 ppm, 500 ppm) on the oxidative stability of a DHAO over a 9-week storage at 30 °C. The oxidative status was monitored during storage by the measurement of peroxide value (PV) and p-anisidine value (p-AV). Changes in eicosapentaenoic acid (EPA) and DHA content, as well as in catechins and tocopherol contents, were also evaluated. The addition of GTE enhanced the oxidative stability of DHAO by reducing the formation of peroxides and secondary oxidation products, whereas α-tocopherol had no significant effect on the PV of oil during storage but led to a significantly higher p-AV. The EPA and DHA content of DHAO was stable in GTE-supplemented samples whereas a decrease was observed in the control and α-tocopherol-supplemented samples. GTE also delayed the degradation of tocopherols initially present in the oil, while catechins resulting from the addition of GTE decreased progressively during the storage period.

The Effect of Carnosol, Carnosic Acid and Rosmarinic Acid on the Oxidative Stability of Fat-Filled Milk Powders throughout Accelerated Oxidation Storage.

The in vitro antioxidant effects of the most potent antioxidants of rosemary, namely carnosol, carnosic acid and rosmarinic acid (c: ca: ra) were assessed in fat-filled milk powders (FFMPs) under accelerated conditions (40 °C and relative humidity (RH) 23%) over 90 days. Lipid oxidation was assessed in FFMPs by measuring peroxide values (PVs), thiobarbituric acid reactive substances (TBARS) and aroma volatiles using headspace (HS) solid-phase microextraction (SPME) coupled to gas-chromatography-mass spectrometry (GC-MS). The antioxidant potency of c: ca: ra exhibited a concentration-related effect (308 ppm > 200 ppm > 77 ppm), with the highest concentration being the most effective at controlling the formation of TBARS and PVs. At a concentration of 308 ppm c: ca: ra were particularly effective (p < 0.05) in inhibiting all the evaluated oxidation indices (primary and secondary) compared to the control samples, but in some cases less effectively (p < 0.05) than butylated hydroxyanisole: butylated hydroxytoluene (BHA: BHT) (200 ppm).

Room Temperature Nanoencapsulation of Bioactive Eicosapentaenoic Acid Rich Oil within Whey Protein Microparticles.

In this study, emulsion electrospraying assisted by pressurized gas (EAPG) has been performed for the first time to entrap ca. 760 nm droplets of the bioactive eicosapentaenoic acid (EPA)-rich oil into whey protein concentrate (WPC) at room temperature. The submicron droplets of EPA oil were encapsulated within WPC spherical microparticles, with sizes around 5 µm. The EPA oil did not oxidize in the course of the encapsulation performed at 25 °C and in the presence of air, as corroborated by the peroxide value measurements. Attenuated Total Reflection—Fourier Transform Infrared spectroscopy and oxygen consumption tests confirmed that the encapsulated EPA-rich oil showed increased oxidative stability in comparison with the free oil during an accelerated oxidation test under ultraviolet light. Moreover, the encapsulated EPA-rich oil showed increased thermal stability in comparison with the free oil, as measured by oxidative thermogravimetric analysis. The encapsulated EPA-rich oil showed a somewhat reduced organoleptic impact in contrast with the neat EPA oil using rehydrated powdered milk as a reference. Finally, the oxidative stability by thermogravimetric analysis and organoleptic impact of mixtures of EPA and docosahexaenoic acid (DHA)-loaded microparticles was also studied, suggesting an overall reduced organoleptic impact compared to pure EPA. The results here suggest that it is possible to encapsulate 80% polyunsaturated fatty acids (PUFAs)-enriched oils by emulsion EAPG technology at room temperature, which could be used to produce personalized nutraceuticals or pharmaceuticals alone or in combination with other microparticles encapsulating different PUFAs to obtain different targeted health and organoleptic benefits.

Validation of the SafTest Peroxide Test Kit for the Measurement of the Peroxide Content of Oils, Tallows, Meat Meals, Potato Chips, and Grain-Based Snacks: AOAC Performance Tested MethodSM 101001.

Peroxide value is used as an indicator of oxidative degradation, off flavor, and rancidity in fat. Traditional methods are dependent on a fat extraction step to extract fat for subsequent titration of peroxides. The SafTest Peroxide Test offers a direct measurement of the peroxide value of vegetable oils, animal fats, meat meal and fish meal products, and potato chips, crackers, and other processed grain-based snack products using micro-analytical and membrane separation principles. The study objective is to validate the SafTest Peroxide Test in an internal study, two contracted studies, and an independent laboratory study. Calibration, LOQ, robustness, selectivity, matrix, shelf life, and lot-to-lot stability were evaluated. The practical dynamic range of the calibration is 0.00 to 0.20 meq/kg. LOQ was determined as 0.02 meq/kg for liquids analyzed neat and 0.08 to 0.46 meq/kg for dry matrixes requiring a 1:4 to a 1:8 dilution. SafTest Peroxide Test relative standard deviations of repeatability (RSDr) averaged 1-13% compared to AOCS Cd 8-53 RSDr% of 1-15% and demonstrated average recoveries of 95.7, 91.5, and 105.2% of the AOCS Cd 8-53 results for olive oil, meat meal and fish, and animal fat and oils, respectively. The SafTest Peroxide Test is an acceptable alternative to AOCS Cd 8-53 and AOCS Cd 8 b-90 for the measurement of peroxide value in oils, fats, meat meal, fish meal, and snack products. The SafTest Peroxide Test uses small reagent volumes, eliminates fat extraction, and provides rapid and standardized procedures for the detection of peroxide.

Quality Assessments of the Fried Oils in Fast Food Restaurants of Yazd, Iran

Background: Oils and fats are among the important constituents of foods. Lipid oxidation can cause changes in taste, flavor, smell, color, texture, and nutritional value of the foods. Deep-fat frying (temperatures of 150 to 200 °C) leads to a series of chemical and physical reactions, so that the oil is oxidized, polymerized, and hydrolyzed. Methods: In a current descriptive cross-sectional study, 100 oil samples were obtained from fast food shops in Yazd city during the spring and summer of 2018. A checklist was prepared including the oil type (oil or fat), odor, color, smoke, and duration of use. The peroxide value (PV), p-anisidine value (p-AV), free fatty acid (FFA) levels, and total polar compound (TPC) of the samples were examined. Results: We found that 93% of the oil samples were in form of liquid. In term of color, 45% of the samples had a dark color and about 57% had an undesirable odor during cooking. In 23% of the fast food shops in Yazd, oil is used more than two days. The measurement of peroxide value showed that 73 samples had peroxide values higher than the allowable limits. The allowable average peroxide value was estimated as 2.33 meq/kg. Results showed that 56 samples had allowable FFA level (less than one), while the others were classified as oxidized oils. The p-AV in 55% of the oil samples were higher than 4. According to the results, 46% of the frying oil samples had TPC of higher than 25%, which showed that they should be discarded. Conclusion: The results showed that majority of the fast food shops in Yazd used highly oxidized oils to prepare their food. The absorption of such oils by food can endanger the public health. Therefore, continuous monitoring of fast foods and restaurants as well as training the staff seem necessary.

Effect of Rosemary Extracts on Stabilitiy of Sunflower Oil Used in Frying.

The oxidative stability of sunflower oil containing rosemary essential oil and extracts in the oil during frying were followed by measuring peroxide value. Variation in the values of L* of the frying oil containing extract was less than that of frying oil containing essential oil. a*-Value of the fried oil containing extract highly significant decreased. Increase in the value of b* of 1. and 2. frying oil with 0.5 % rosemary essential oil was less. b* Value of the frying oils containing rosemary extract increased compared to b* values of frying oils containing essential oil. b* Value of the frying oil that the essential oil of rosemary added showed less increase than b* value of the frying oil that extract of rosemary. The viscosity values of frying oils containing rosemary extract changed between 30.3 mPas (1. frying oil containing 0.5% extract) and 35.5 mPas (2. frying oil containing 0.5% extract). In addition, free fatty acidity values of frying oils containing essential oil at 0.1, 0.3 and 0.5% levels ranged from 0.160% (1. frying oil containing 0.5% essential oil) to 0.320% (1. frying oil containing 0.3% essential oil). Peroxide values of frying oils containing rosemary extracts were determined between 12.84 meq O2/kg (1. frying oil containing 0.1% extract) and 28.98 meq O2/kg (2. frying oil containing 0.1% extract). Peroxide value of frying made with 0.3 % the rosemary essential oil increased less than that of made with the raw sunflower oil (control) (p < 0.05). Whenever rosemary essential oil and rosemary extract compare, the essential oil seems to be more effective on the peroxide value of the frying oil. The essential oil of rosemary have been effected more from the extracts of rosemary on the oxidative stability of sunflower oil.

Lime (Citrus aurantifolia) Peel Effect on Peroxide Value of Cooking Oil

Cooking oil is a staple in everyday life. Economic has been the reason of the repeated use. The quality of cooking oil can be known from taste, colour, and aroma. In terms of aroma, rancidity is caused by the presence of peroxide. Peroxide is a sign of oil breakdown or damage due to oxidation, which causes a rancid odour. Lime peel is used as an antioxidant because it contains vitamin C, flavonoids, and carotenoids. Damage to cooking oil can’t be prevented but can be lowered by giving antioxidants from lime peel. This study aims to determine the effect of lime peel extract on the peroxide number in cooking oil. Antioxidant content of lime peel was measured by spectrophotometric absorbance of vitamin C, flavonoid and carotene content. Peroxide value was asses by titration. Oil clarity was also measured by spectrophotometric to confirm peroxide value. The method used in this study was an experiment using a complete randomized design with two factorials. The first factor is the type of solvent (distilled water, ethanol, and chloroform). The second factor is the extract concentration (70, 80, and 90) μg / ml. Peroxide number measurement was analysed using ANOVA (p <0.05) and continued with the Duncan test. Antioxidant content showed that lime peel contains vitamin C, flavonoid and carotene with highest in vitamin C. Peroxide value measurement obtained that distilled water extract concentration of 90 μg / ml had the lowest peroxide number of 0.56 MEquiv O2 / Kg while the highest value was found in distilled water extract of 80 μg / ml concentration (0.96.56 Mequiv O2 / Kg). Clarity of the oil was found best at 90µg/ml concentration (0.38). It can be concluded that lime peel extract significantly gave effects on peroxide number of cooking oil. Both concentration and extract solvent determine the peroxide number.

FT-IR and Raman spectroscopy data fusion with chemometrics for simultaneous determination of chemical quality indices of edible oils during thermal oxidation

A rapid, non-destructive and robust method for measuring peroxide values (PVs) and acid values (AVs) of common edible oils (soybean, rapeseed, sunflower and peanut) simultaneously under various thermal oxidation was explored by FT-IR and Raman spectroscopy data fusion strategy. Uninformative variable elimination (UVE) and successive projections algorithm (SPA) methods were used for feature variables extraction, quantitative models for prediction of chemical quality indices were established using partial least squares regression (PLSR) algorithm. The bands associated with vibration of C=O and C=C stretching were highly correlated with PVs and AVs, data fusion of the two spectra showed the best modeling results when variables identified by SPA were used. For modeling of PVs, the resulting Rc2 and Rp2 were 0.964 and 0.939, RMSEC and RMSEP were 0.060 and 0.080. For modeling of AVs, the resulting Rc2 and Rp2 were 0.955 and 0.919, RMSEC and RMSEP were 0.025 and 0.027.

Iodide reaction times of peroxyhemiacetals (PHAs) in the peroxide value titration; implications for the testing of citrus oils

AbstractLimonene and linalool are major components in many essential oils, and both may autoxidize under certain conditions to form terpene hydroperoxides (THPs), which are reported to be sensitizers that may cause allergic contact dermatitis. This laboratory previously reported that peroxyhemiacetals (PHAs) may be present in some citrus oils, formed by reaction of THPs with endogenous aldehydes. It was also shown that PHAs can dissociate back to the corresponding THPs in polar solvation environments. Because of this potential for reversion to THPs, the analysis of PHAs is important in the context of measuring peroxide values in products. The fragrance industry currently utilizes iodometric titration to monitor THP levels in many raw materials; the currently accepted method requires that THPs in the sample are allowed to oxidize excess added iodide to molecular iodine for a one‐minute reaction time. The iodine generated is then titrated with thiosulfate to give the peroxide value. This paper reports on the iodide reaction time required for PHAs to be quantitatively measured by such an iodometric titration technique, and on the implications to citrus oil raw material testing.

Fatty Acid Content, Oxidation Markers and Mercury in Fish Oil Supplements Commercialized in Brasília, Brazil

Fish oil supplements are good sources of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, which are important in the prevention and treatment of hypertriglyceridemia. The purpose of this study was to examine the content of EPA and DHA, oxidation markers and mercury of fish oil supplements marketed in Brasilia, Brazil. Fatty acid contents were determined by gas chromatography using internal (C23:0) and external methyl ester standards. For this analysis, samples were prepared by alkali-catalyzed methylation with boron trifluoride (14% in methanol). Mercury was determined by direct vapor detection method. Oxidation markers were evaluated by measuring peroxide value (PV), anisidine value (AV) and by calculating TOTOX. The adequacy of EPA and DHA ranged from 75.9 to 105.1% and from 88.9 to 137.4%, respectively, compared to the information in the label. Mercury concentration was above limit of quantification levels, between 11 and 15 mg/kg in 14.4% of the products. Twenty percent of the products exceeded recommended levels of PV and TOTOX. Despite the high percentage of adequacy of the parameters analyzed, about 2/3 of the products showed some inadequacies according to the law. These data deserve concern due to the potential side effects of oxidized and contaminated fish oils to their proclaimed health benefits. This survey shows the relevance of constant monitoring of fish oil quality, considering current legislation and scientific advance. DOI: http://dx.doi.org/10.17807/orbital.v11i3.1390

Comparison of Bioactive Compounds of Matricaria recutita Extracted by Ultrasound and Maceration and their Effects on Preventing Sunflower Oil During Frying

Background: It is important to study about the use of natural antioxidants as alternatives to synthetic ones due to the possibility of carcinogenic effects of synthetic antioxidants. This study is comparing the effect of the ultrasound-assisted and maceration extraction methods on antioxidant activity of Matricaria recutita. Methods: Bioactive compounds including phenolic, tocopherol, flavonoid and tannins and antioxidant activity of the extracts were evaluated. Moreover, extracts obtained from ultrasound and maceration methods were added to sunflower oil without any antioxidants at level of 200, 500 and 800 ppm, after that samples were heated at 180°C. Oxidation of the samples were evaluated after 0, 4, 8, 12, 16, 20 and 24 hours by measuring Peroxide Value (PV), Conjugated Diene (CD), Iodine Value (IV), Carbonyl Value (CV), Total Polar Compounds (TPC), Oil Stability Index (OSI), Color Index (CI) and acid value (AV). Results: The result showed total phenol (42.90 mg gallic acid/g extract), tocopherol (120.46 &amp;#181;g &amp;#945; - tocopherol/ml extract), flavonoid (2.64 mg/100 g extract) and tannins (3.89 mg gallic acid/g extract) of ultrasound extracts were higher than maceration extracts. Antioxidant activity of the extract was evaluated by DPPH assay which indicated 800 ppm of the Matricaria recutita extracted by ultrasound was the highest radical scavenging ability. Conclusion: Result indicated both ultrasound and maceration extracts could increase the oil oxidative stability but could not increase compared to BHA. In most cases, the extract samples by ultrasound had a better effect on stabilizing of sunflower oil during frying.

Improving Oxidative Stability of Flaxseed Oil by Encapsulation in Electrospun Flaxseed Mucilage Nanofiber

In this study, the potential of flaxseed mucilage nanofiber, as wall material, for encapsulation of flaxseed oil (FO) was investigated. Four series of O/W emulsions at different ratios of FO (0, 10, 20, and 40% w/w) were used to fabricate FO-loaded nanofibers and encapsulation efficiency (EE), loading capacity (LC), and the nanofiber morphology was investigated. Finally, the oxidative stability of entrapped oil as well as bulk FO was investigated during storage by measuring peroxide value (PV), thiobarbituric acid-reactive substances (TBARS), and totox value. The chemical structure and thermal properties of the nanofiber and oxidative stability of loaded FO were also evaluated on the selected best ratio. The highest LC (23.6%) was obtained in nanofiber containing 40% (w/w) FO which had uniform morphology with an average diameter of 332.9 nm. In regard to oxidation tests, PV of encapsulated FO increased from 8.1 to 25.5 meq O2/kg while for bulk oil, the value elevated from 1.4 to 25.5 meq O2/kg during 14 days. Moreover, TBA of protected FO increased to 78.49 mg/kg oil while in control sample, the index reached at 107.3 mg/kg oil. The results of oxidation test demonstrated that the nanofiber was successful to improve the oxidative stability of flaxseed oil.

Effects of Chelating Agents and Salts on Interfacial Properties and Lipid Oxidation in Oil-in-Water Emulsions.

The effects of chelating agents and salts on the interfacial characteristics and oxidative stability of oil-in-water emulsions containing an endogenous concentration of metal ions were investigated. Emulsions were fabricated by high-pressure homogenization of 10% oil phase (sacha inchi oil) and 90% aqueous phase (1% Tween 60 in phosphate buffer solution, pH 7, 50 mM). The oxidative stability of the emulsions was characterized by measuring peroxide values and thiobarbituric acid reactive substances throughout storage. Endogenous iron and copper ion levels in the emulsions were detected by atom absorption spectroscopy as 1.99 and 0.86 ppm, respectively. Incorporation of chelating agents, either ethylenediaminetetraacetic acid or sodium citrate, into the emulsions effectively inhibited lipid oxidation, showing that even these low levels of endogenous metal ions ( parts per million) were sufficient to promote oxidation. Conversely, the addition of monovalent salts, NaCl or KCl, slightly increased the rate of lipid oxidation in the emulsions, which was attributed to their impact on the physical properties of the surfactant layer at the oil droplet surfaces. The impact of chelating agents and salts on the electrical characteristics (ξ potential) and relaxation time (TR) of the surfactant-coated lipid droplets were characterized by particle electrophoresis and nuclear magnetic resonance spectroscopy, respectively. The chelating agents and salts altered the surface potential of the droplets, indicative of a change in the adsorption of metal ions to the droplet surfaces. Moreover, they altered the arrangement of surface-active molecules at the droplet surfaces, thereby impacting the contact of pro-/antioxidants with the oil phase. These results have important implications for the formulation of emulsion-based materials that are more stable to lipid oxidation.