Antioxidant activity of Satureja bachtiarica Bunge essential oil in rapeseed oil irradiated with UV rays

In this study, application of two concentrations (0.03 and 0.06%) of Satureja bachtiarica Bunge essential oil (EO) were examined on oxidative stability of rapeseed oil (RO) during autoxidation and after irradiation with ultraviolet (UV) rays (exposition 30 min) at 60°C. The main compounds of EO extracted by the recently designed ohmic ultrasonic extractor (distillation unit) were identified as thymol (～30%), carvacrol (～15%) and caryophyllene oxide (～12%). Antioxidant activity of EO was compared to butylated hydroxytoluene (BHT) during autoxidation. The UV rays induced oxidation process in RO samples both with and without additives. This effect was more vigorous when irradiation was carried out prior to addition of the additives. It was further established that antioxidant activity of EO was better than BHT in samples treated by UV rays. Moreover, EO was able to reduce the stable free radical 2, 2′‐diphenyl‐1‐picrylhydrazyl (DPPH) with a 50% inhibition concentration (IC₅₀) of 32.5 ± 0.6 µg/mL. The findings show the good potential of EO when it is used as a natural antioxidant in food lipids.     

Canola extract as an alternative natural antioxidant for canola oil

The antioxidative activity of ethanolic extracts of canola meal at 100, 200, 500 and 1000 ppm on refined-bleached (RB) canola oil was examined and compared with commonly used synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), BHA/BHT/monoglyceride citrate (MGC) andtert-butyl-hydroquinone (TBHQ). Stability of RB oil was monitored under Schaal oven test conditions at 65°C over a 17-d period. Progression of oxidation was monitored by weight gain, peroxide, conjugated diene, 2-thiobarbituric acid and total oxidation values. Canola extracts at 500 and 1000 ppm were more active than BHA, BHT and BHA/BHT/MGC and less effective than TBHQ at a level of 200 ppm.     

Effect of evening primrose extracts on oxidative stability of sunflower and rapeseed oils

Antioxidative activities of evening primrose seed meal extracts in sunflower and rapeseed oils were compared with that of commercially used antioxidants, namely butylated hydroxytoluene (BHT), ascorbylpalmitate as well as Grindox‐118. The study was carried out under Schaal oven conditions at 60 °C and the weight gain was followed up by p‐anisidine value measurement following the oxidation. An Oxidograph apparatus monitored the oxidation of oils at 110 °C. Among the examined extracts, the ethyl acetate extract (0.2%), containing only 87 mg/g of total phenolics, exhibited a stronger antioxidant activity than BHT (0.01%) and effectively stabilised both oils. A strong antioxidative effect was also noted for the ethanol‐ethyl acetate extract (168 mg/g of total phenolics). The study showed that addition of ethyl acetate and ethanol‐ethyl acetate extracts could extend the sunflower and rapeseed oils shelf‐life by protecting oils from further decomposition that naturally occurs during thermal treatments.     

Evaluation of antioxidant capacity of sesamol and free radical scavengers at different heating temperatures

Sesamol is a natural antioxidant found in sesame oil from roasted sesame seeds. Activation energy and antioxidant capacity of sesamol were determined and compared with other free radical scavengers (FRSs) including tert‐butylated‐hydroxyquinone (TBHQ), butylated‐hydroxyanisol (BHA), or α‐tocopherol in a lard model system treated with different heating temperature. Each FRS was added in lard and heated at 90, 120, 150, and 180°C for 48, 24, 8, or 2 h, respectively and antioxidant capacity was evaluated by conjugated dienoic acid (CDA) value, conjugated diene hydroperoxides, p‐anisidine value (p‐AV), and a modified 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) method. Apparent activation energy of sesamol was determined as 12.98 kcal/mol in a lard model system. Antioxidant capacity of sesamol was as good as that of TBHQ and was higher than those of BHA and α‐tocopherol at 90, 120, and 150°C based on CDA, conjugated diene hydroperoxides, and p‐AV assays. The results of a modified DPPH method showed that each FRS showed different distribution of radical scavenging compounds from oxidized lipids (RSOLs) during oxidation. Sesamol may replace synthetic FRSs like TBHQ and BHA in processed foods treated with high temperature. Practical application: Processed foods are frequently treated with high temperature during oven‐drying, roasting, baking, and deep‐fat frying. This study showed that sesamol, one of natural antioxidants, had stronger antioxidant capacities than other synthetic FRSs at the temperature ranges from 90 to 180°C. The results of this study can be applied in food industries producing deep‐fat fried foods including snacks, chips, and French fries to extend the shelf‐life of final foods with high temperature treatment.     

STABILITY AND SENSORY QUALITY OF SPRAY DRIED AVOCADO PASTE

ABSTRACT

Avocado (Persea americand) paste was spray dried at inlet air temperature of 180°C, 80°C outlet air temperature, air velocity of 27 m/s and a feed flow rate of 0.642 l/min. Lipids in the paste were emulsified using 10 % Monoacylglyceride (MAG). Treatments were applied according to the following antioxidants mixtures: 1) BHA (butylated hydroxyanisole) + BHT (butylated hydroxytoluene) (0.05 % each); 2) TBHQ (Tertiary butylated hydroxyquinone) + Citric Acid (0.05 + 0.1 %); 3) BHA + BHT + Citric Acid (0.05 + 0.05 + 0.1 %); 4) BHA + Propyl gallate (0.05 + 0.05 %); or 5) BHA + Propyl gallate + Citric acid (0.05 + 0.05 + 0.1 %). Samples were stored at 6, 12, 25, 28 and 40 °C. Peroxide values were determined periodically. Development of rancidity was detected by sensory evaluation of the samples. For samples kept at 6 and 12 °C, an antioxidant mixture containing BHA and propyl gallate at 0.05% gave the least protection to the stored avocado powder. The mixture containing TBHQ and citric acid yielded the lowest rancidity development.     

Polyphenolic fractions improve the oxidative stability of microencapsulated linseed oil

The main objective of this study was to evaluate the effect of incorporating polyphenolic‐enriched fractions from murta leaves on the oxidative stability of linseed oil microencapsulated by spray drying. For this purpose, polyphenol‐enriched fractions from murta leaves were separated by gel permeation chromatography and chemically characterized. The oxidative stability of microencapsulated linseed oil (MLO) with antioxidants was evaluated in storage conditions at 25°C for 40 days. The antioxidant effects of the polyphenolic fractions and commercial antioxidants (BHT and trolox) on microencapsulated oil were evaluated by the value of conjugated dienes, peroxide, and p‐anisidine. In the initiation step of the oxidation, no significant oxidation delay (p>0.05) in MLO containing fractions F₆, F₈, or BHT and trolox was observed. However, in the termination step of the oxidation, the addition of fractions F₆, F₈, and BHT and trolox decreases significantly (p ≤ 0.05) the rancidity in MLO. Furthermore, the results of this study demonstrated the importance of the addition of natural antioxidants such as fractions of murta leaf extract in microencapsulated linseed oil to increase its resistance to oxidation. Practical applications: For incorporating linseed oil, a source of omega‐3 fatty acids, in the diet it is necessary to protect it against oxidative rancidity, the main cause of deterioration that affects food with a high unsaturated fat content. Microencapsulation is effective in retarding or suppressing the oxidation of unsaturated fatty acids and natural plants extracts are effective in inhibiting the lipid oxidation of microencapsulated oil. The use of process technology and a natural additive is expected to increase storage stability and enable its use in dry foods such as instant products. Linseed oil can be used in human nutrition as well as in animal feed as a replacement for fish oil.     

Food Additives Reducing Volatility of Antioxidants at Frying Temperature

At frying temperature, antioxidants are lost not only by reaction with radicals formed by oil oxidation but also by decomposition and evaporation before they are able to exert antioxidant activity. In this study, it was hypothesized that an additive that can bind or interact with an antioxidant could reduce volatility of the antioxidant at frying temperature. Three synthetic antioxidants, tert‐butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which have relatively high volatility, were used as antioxidants in this study to examine the hypothesis. Thermogravimetric analysis (TGA) experiments showed that all 22 additives tested in this study effectively reduced volatility of the antioxidants. An NMR study showed that signals of BHT shifted by addition of an additive, evidencing the interaction between the two substances in the chloroform solution. To examine the effect of these interactions on antioxidant activity, heating tests were conducted with soybean oil (SBO) containing 200 ppm antioxidants at 180 °C. Oxidation was monitored with ¹H NMR for loss of olefinic protons and bisallylic protons in SBO and with gel permeation chromatography (GPC) for polymerized triacylglycerols (PTAG). Improved antioxidant activity of the antioxidants were observed when combined with several additives tested in this study, and HPLC analysis showed that the antioxidants were effectively reserved by the additives in SBO during the heating process. The concentrations of the antioxidants retained in SBO were relatively well correlated with the antioxidant activity.     

Stability of tapioca chips fried in RBD palm olein treated with antioxidants

The effectiveness of tertiarybutylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in stabilizing tapioca chips was assessed by determining the peroxide andp-anisidine values, absorbances at 232 nm and 268 nm and the 18:2/16:0 ratios of oil extracted from tapioca chips. The order of effectiveness of the antioxidants in stabilizing the chips was found to be TBHQ > BHT > BHA. The order of effectiveness of antioxidants, TBHQ > BHT > BHA, was maintained for chips from corresponding 1st, 4th and 7th fryings. The loss of antioxidants during storage could not be directly related to oxidation parameters.     

Improved oxidative stability of sunflower oil in the presence of an oxygen-scavenging film

The oxidative stability of sunflower oil (SFO) was measured during storage at 23 and 37°C in the presence of a novel oxygen-scavenging film that contained polyfuryloxirane (PFO). Commercially refined and deodorized SFO was stored in a lighted room in sealed transparent packages containing either PFO film or an antioxidant, 0.02% butylated hydroxytoluene (BHT). Oxidative stability was evaluated by determination of peroxide values and gas-chromatographic measurement of headspace hexanal. SFO stored in the presence of the oxygen-scavenging film was more stable than oil stored without the film, or than film stored with 0.02% BHT. The PFO film scavenges oxygen through energy-transfer sensitization of singlet oxygen. The film is doped with eosin and the naturally-occurring dye, curcumin, which absorb over a wide range of visible wavelengths. Curcumin transfers its absorbed energy to eosin, which sensitizes the production of singlet oxygen. The singlet oxygen is scavenged by PFO. The use of two dyes increases the efficiency of the sensitization process, reducing the illumination time and intensity required for effective oxygen scavenging.     

Effect of selected antioxidants on the stability of virgin olive oil

Virgin unrefined olive oil was protected from oxidation with the antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylhydroquinone (TBHQ) and in one case propyl gallate (PG). All the antioxidants improved the stability of olive oil under accelerated conditions (oven test) and storage conditions at 50 C. In the oven test, where the type of oil used was the same as that used in long-term storage studies (room temperature and 50 C) the relative inhibition effect of the antioxidants was in the following order: TBHQ = BHA > BHT. The combinations of BHA and BHT with TBHQ displayed better stabilizing qualities. Antioxidants did not prevent peroxide formation in olive oil stored at room temperature in daylight; these samples oxidized to a high degree, probably due to the catalytic action of chlorophyll. Citric acid (CA) used alone did not affect the oxidative stability of the oil in the oven test and at room temperature in the dark, but exhibited a negative effect at 50 C. The reduction in peroxide content with teritary butylhydroquinone (TBHQ) in the dark at 50 C was greater than anticipated from the oven studies. Potency of the antioxidants under these conditions (50 C) was in the following order: TBHQ> BHT > BHA. The combinations of BHA 0.01% or BHT 0.01% with TBHQ 0.005% used in the dark at 50 C were less effective than TBHQ 0.01%.     

Antioxidant efficacy of methanolic extracts of peanut hulls in soybean and peanut oils

Antioxidant activity of methanolic extracts of peanut hulls (MEPH) was evaluated in soybean and peanut oils after accelerated oxidation at 60°C. Results showed that the oils with 0.12, 0.48, and 1.20% MEPH had significantly (P<0.05) lower peroxide values and acid values than the control after storage at 60°C. Moreover, oils with 0.48 and 1.20% MEPH were significantly (P<0.05) superior to 0.02% butylated hydroxyanisole (BHA) in reducing oxidation of both oils. Negative synergism was observed when 0.48 and 1.20% MEPH were mixed with 0.01% dl-α-tocopherol or 0.01% BHA in soybean oil compared to MEPH alone.     

Effects of natural and synthetic antioxidants on changes in refined, bleached, and deodorized palm olein during deep-fat frying of potato chips

The effects of antioxidants on the changes in quality characteristics of refined, bleached, and deodorized (RBD) palm olein during deep-fat frying (at 180°C) of potato chips for 3.5 h/d for seven consecutive days in five systems were compared in this study. The systems were RBD palm olein without antioxidant (control), with 200 ppm butylated hydroxytoluene (BHT), 200 ppm butylated hydroxyanisole (BHA), 200 ppm oleoresin rosemary, and 200 ppm sage extract. Fried oil samples were analyzed for peroxide value (PV), thiobarbituric acid (TBA) value, iodine value (IV), free fatty acid (FFA) content, polymer content, viscosity, E^1% _{1 cm} at 232 and 268 nm, color, fatty acid composition, and C_18:2/C_16:0 ratio. Sensory quality of the potato chips fried in these systems prior to storage was also evaluated. The storage stability of fried potato chips for 14 wk at ambient temperature was also determined by means of the TBA values and sensory evaluation for rancid odor. Generally, in the oil, oleoresin rosemary gave the lowest rate of increase of TBA value, polymer content, viscosity, E^1% _{1 cm} at 232 and 268 nm compared to control and three other antioxidants. The order of effectiveness (P<0.05) in inhibiting oil oxidation in RBD palm olein was oleoresin rosemary > BHA > sage extract > BHT > control. Prior to storage, the sensory evaluation of fried potato chips for each system showed that there was no significant (P>0.05) difference in terms of flavor, odor, texture, and overall acceptability. The same order of effectiveness (P<0.05) of antioxidants was observed for storage stability study of fried potato chips by TBA values. However, there was no significant (P > 0.05) difference in sensory evaluation for rancid odor during storage periods.     

Lipid oxidation inhibiting capacities of blackseed essential oil and rosemary extract

Lipid oxidation is the main deterioration process that occurs in vegetable oils containing lipid molecules with polyunsaturation. The aim of the present study was to investigate the possible effects of blackseed (Nigella sativa L.) essential oil (BEO) and rosemary (Rosmarinus officinalis L.) extract (RE) on stabilization of sunflower oil under accelerated storage conditions. RE was obtained by soxhlet extraction using methanol, whereas BEO was hydrodistilled from the blackseed extract obtained by extraction using petroleum ether (b.p. 40–60°C). The results indicate that both extracts stabilize sunflower oil to a certain extent, the extent being greater with RE than with BEO based on measurements of peroxide value, p‐anisidine value, amount of nonoxidized linoleic acid in saponified oil samples by HPLC‐DAD, concentration of conjugated diene hydroperoxide, and UV light absorption. The oil stabilizing effect of BEO against lipid oxidation, especially at concentrations of 0.06 and 0.1 g/100 g oil was found to increase as the temperature increased, according to principal component analysis results. Based on its strong lipid oxidation inhibiting capacity, RE can be used as a potential natural extract for stabilizing sunflower oil against oxidation. BEO, at carefully selected concentrations, can be suggested as an alternative supplement of plant origin for improving oil stabilization. Practical applications: Sunflower oil is a widely used vegetable oil for cooking and frying, and has a high linoleic acid content of about 40–70%. Here we show that sunflower oil can be stabilized by adding rosemary and blackseed extracts. The treatment can be useful especially in applications which require heating the oil to high temperatures.     

Stabilization of seal blubber and menhaden oils with green tea catechins

Catechins, namely (−)epicatechin (EC), (−)epigallocatechin (EGC), (−)epicatechin gallate (ECG) and (−)epigallocatechin gallate (EGCG), were isolated from commercial Chinese green leaves. The antioxidant activity of isolated catechins was compared with those of α-tocopherol, butylated hydroxyanisole (BHA), butylated hydroxytolene (BHT) andtert-butylhydroquinone (TBHQ), all at 200 ppm, in refined, bleached and deodorized seal blubber oil and menhaden oil. The study was carried out under Schaal oven test conditions at 65°C over a 144-h period, except for weight gain measurements, which were continued for up to 200 h. Progression of oxidation was monitored by measuring changes in weight gain and values of peroxide, conjugated diene, and 2-thiobarbituric acid-reactive substances. Oils treated with tea catechins showed excellent oxidative stability as compared with samples that contained commonly used antioxidants, such as α-tocopherol, BHA, BHT, and TBHQ. The potency of catechins in prevention of oxidation of marine oils was in the decreasing order of ECG> EGCG> EGC> EC; ECG was slightly more effective than TBHQ in systems studied.     

Inhibition of soybean oil oxidation by extracts of dry beans (Phaseolus vulgaris)

Polyphenolic compounds were extracted from pinto, kidney, white (Great Northern), pink, and black beans by hot methanol extraction and added to soybean oil. Oil oxidation was assayed by thiobarbituric acid-reactive substances (TBARS). All bean polyphenolics extracts exhibited similar antioxidant capacity in delaying the onset of iron-catalyzed oxidation better than butylated hydroxyanisole (BHA), propyl gallate (PG), and ascorbic acid. Bean polyphenolic compounds were stable after heating to 50°C and maintained their antioxidant potential after 3 mon at 4°C. Bean extracts effectively inhibited iron-catalyzed oxidation of soybean oil, probably by chelating metal ions, because no antioxidant effect was observed when soybean oil was oxidized without an iron catalyst.     

Thermal stability of some commercial synthetic antioxidants

Synthetic antioxidants are widely applied substances in human food and in animal feed industries. These products, which are mainly derived from phenolic structures, were developed to avoid or retard the oxidative rancidity of fats and oils when added either to raw material or to end-products. Synthetic antioxidants such as butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tertiary butylhydroxyquinone (TBHQ), and ethoxyquin (EQ) are frequently applied during the cooking of the by-products (viscera, blood, and feathers) in the poultry feed industry. However, results in terms of oxidative prevention are unequal and usually modest. Because information about the thermal stability of synthetic antioxidants is scarce, we developed a laboratory model that simulates the cooking of poultry by-products to study the effectiveness of BHT, BHA, TBHQ, and EQ. The antioxidants were thermally treated at 100–200°C, over 1 or 2 h. The effectiveness of each antioxidant after the thermal treatment was assessed with the Rancimat test by measuring the modification of the induction period for the oxidation of sardine oil and comparing it to the oxidation kinetics of the oil without added antioxidants. Within our experimental conditions, all antioxidants assayed showed different degrees of thermal instability. BHT and TBHQ were effective as antioxidants at temperatures up to 175°C, exhibiting only 25 to 30% inactivation. However, BHA and EQ were inactivated by 70 and 60%, respectively, at 150°C. Heating time (1 and 2 h) at a given temperature did not significantly modify the behavior of the antioxidants assayed. EQ is the most frequently applied antioxidant to prevent oxidative rancidity in the cooking of poultry by-products. However, according to our results, EQ and BHA, which is another antioxidant frequently used by the poultry industry, are less suitable     

Long-term storage stability of biodiesel produced from Karanja oil

Biodiesel is an alternative diesel fuel made from vegetable oil or animal fat. It is more susceptible to oxidation or autoxidation during long-term storage than conventional petrodiesel. Karanja oil methyl ester (KOME) was prepared and stored for a period of 180 days under different storage conditions. The physicochemical parameters, peroxide value (PV) and viscosity (v) of samples were measured at regular interval of time under different storage conditions. The stability of Karanja oil methyl ester (KOME) was studied under different storage conditions. The stability of KOME was improved by adding different antioxidants Tert-Butylated Hydroxy toluene (BHT), Tert-Butylated Hydroxyanisole (BHA), Pyrogallol (PY), Propyl galate (PrG) and Tert-Butyl Hydroxyl Quinone (TBHQ). The effectiveness of three antioxidants BHT, BHA and PrG on Karanja oil methyl ester was examined at varying loading level during the storage period.     

Effect of antioxidants on the oxidative stability of methyl soyate (biodiesel)

Biodiesel, an alternative diesel fuel derived from transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain fatty acid alkyl esters. When exposed to air during storage, autoxidation of biodiesel can cause degradation of fuel quality by adversely affecting properties such as kinematic viscosity, acid value and peroxide value. One approach for increasing resistance of fatty derivatives against autoxidation is to treat them with oxidation inhibitors (antioxidants). This study examines the effectiveness of five such antioxidants, tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PrG) and α-Tocopherol in mixtures with soybean oil fatty acid methyl esters (SME). Antioxidant activity in terms of increasing oxidation onset temperature (OT) was determined by non-isothermal pressurized-differential scanning calorimetry (P-DSC). Analyses were conducted in static (zero gas flow) and dynamic (positive gas flow) mode under 2000 kPa (290 psig) pressure and 5 °C/min heating scan rate. Results showed that PrG, BHT and BHA were most effective and α-Tocopherol least effective in increasing OT. Increasing antioxidant loading (concentration) showed sharp increases in activity for loadings up to 1000 ppm followed by smaller increases in activity at higher loadings. Phase equilibrium studies were also conducted to test physical compatibility of antioxidants in SME-No. 2 diesel fuel (D2) blends. Overall, this study recommends BHA or TBHQ (loadings up to 3000 ppm) for safeguarding biodiesel from effects of autoxidation during storage. BHT is also suitable at relatively low loadings (210 ppm after blending). PrG showed some compatibility problems and may not be readily soluble in blends with larger SME ratios. Although α-Tocopherol showed very good compatibility in blends, it was significantly less effective than the synthetic antioxidants screened in this work.     

Antioxidant activity of amino acids bound to trolox-C

Various amino acids, selected for their potential antioxidant activity, were, covalently attached to 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox-C), a lower homolog of vitamin E that has great antioxidant effectiveness. The resulting Troloxylamino acids (T-AA) had greater antioxidant effectiveness than Trolox-C in a linoleate emulsion system oxidized by hemoglobin. Troloxyl-tryptophan-methyl ester and Troloxyl-methionine-methyl ester were the most effective T-AA evaluated in the linoleate emulsion. However, butylated hydroxyanisole (BHA), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and α-tocopherol were more antioxidant than any T-AA in the emulsion system. In a Schaal oven test at 45 C. Trolox-C was by by far the most effective antioxidant evaluated in corn oil. BHT and Troloxylcysteine had significant antioxidant activity in corn oil, but no other T-AA was antioxidant in corn oil. In butter oil, Trolox-C again had the highest antioxidant activity, and BHA and BHT were also highly antioxidant. All t-AA had antioxidant activity in butter oil, with Troloxyl-methioninc and Troloxyl-cysteine having the grcatest antioxidant effectiveness. The T-AA of highest antioxidant activity were hydrolyzed by chymotrypsin and/or trypsin, in vitro.     

The Behaviour of Phenolic Antioxidants,Synergists and their Mixtures in Two Vegetable Oils

Tertiary butylhydroquinone (TBHQ), hydroquinone (HQ), propyl gallate (PG), butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) had much higher antioxidant activity in crude safflower oil than in a commercial brand vegetable oil (Bint oil). The following active oxygen (AOM, hours at 97.8° C) and storage stability (days at 45° C) values for each antioxidant in safflower oil were; (27.9, 105.0), (21.2, 44.8), (15.3, 45.5), (9.8, 36.8) and (7.9, 33.5) respectively compared with (6.8, 31.5) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. The same values in Bint oil were: (9.0, 34.3), (9.0, 28.3), (9.4, 41.0), (7.3, 28.5) and (6.2, 2.5) respectively compared with (5.3, 23.3) for the control. Ascorbyl palmitate (AP), ascorbic acid (AA) and citric acid (CA) were found to improve the AOM stability of both oils. AP was more effective and CA least effective in safflower oil, whereas the reverse was true in Bint oil. The five antioxidants were individually blended with the three synergists (0.01 % of each) and the 15 combinations added to each oil and compared with the antioxidant controls at 0.02 %. Safflower oil stability was greater with pure TBHQ, HQ and PG than with any of the synergist mixtures whereas the BHA, BHT-synergist mixtures were found equal or superior to that treated with BHA or BHT alone. Bint oil treated with CATBHQ or CA-HQ mixtures showed improved stability compared to oils treated with these antioxidants alone. However, the AOM method alone suggested CA-PG, CA-BHA and CA-BHT mixtures improved the stability compared to the oil-antioxidant controls. Chelation of metals by CA was assumed to be the primary cause of this synergism, whereas AP and AA behaved more like weak antioxidants.