Antioxidant efficiency of oregano during frying and storage of potato chips

The effect of oregano on the oxidative stability of cottonseed oil during frying of potato chips and on the storage stability of the produced chips was studied. The ground spice or an ethanol‐derived extract thereof was added to the oil at a concentration of 2 g l^?1 (dry basis) before frying. The results showed that both ground oregano and its ethanol‐derived extract decreased the rates of accumulation of conjugated dienes, polar compounds, polymerised triglycerides, dimeric triglycerides as well as p‐anisidine value (p‐AV) of the frying oil. The major decrease was observed in the accumulation of polymerised and dimeric triglycerides. The accumulation of oxidised triglycerides showed a low decrease with the addition of oregano, while the hydrolytic compounds formed during frying were not affected. No significant difference (at 95% significance level) between ground oregano and its ethanol‐derived extract was observed. The storage stability of potato chips removed from the fryer at various time intervals was estimated by the rates of increase in peroxide value and conjugated dienes of the oil absorbed in the chips. Both rates were depressed when oregano was added to the frying oil; the protective action of oregano extract was considerably greater (at 95% significance level) than that of ground oregano. Copyright © 2003 Society of Chemical Industry     

Effect of tertiarybutylhydroquinone on lipid oxidation in fish crackers

The effect of tertiarybutylhydroquinone (TBHQ) in retarding lipid oxidation in fish crackers fried in refined, bleached and deodorised palm olein (RBD olein) during storage was evaluated. The indices of lipid oxidation used were the peroxide and p-anisidine values and u.v. absorbances at 232 and 268 nm of oil extracted from fish crackers stored at 60°C. Two methods for TBHQ incorporation into the fish crackers were used. Fish crackers that were prepared by frying of fish chips in RBD olein containing TBHQ were more stable towards oxidative rancidity than control fish crackers prepared with RBD olein without TBHQ. The rate of lipid oxidation in fish crackers prepared from fish chips that were made with TBHQ in the dough formulation and fried in RBD olein without TBHQ was slightly higher than in control fish crackers. A storage study carried out at room temperature (30°C) showed the same trend in relative rates of lipid oxidation. The study showed that the incorporation of TBHQ into the frying medium was an effective means of retarding the onset of rancidity in fried fish crackers while the incorporation of TBHQ into the dough mixture made the fish cracker slightly more susceptible towards lipid oxidative reactions.     

Effect of oregano and rosemary essential oils on lipid oxidation of stored frozen minced gilthead sea bream muscle

The study aimed to determine the effect of oregano and rosemary essential oils addition to minced gilthead sea bream muscle on lipid oxidation during frozen storage. Each essential oil was added to minced fish muscle at 500 mg/kg concentration which then was stored at ?22 °C for 12 months. Oregano essential oils inhibited the formation of conjugated diene and triene hydroperoxides and thiobarbituric reactive substances when compared with untreated samples after the first month and rosemary essential oils after the first and third month of frozen storage. Oregano and rosemary essential oils could be used as ingredients to prevent oxidation in stored frozen minced gilthead sea bream muscle, when long term preservation is not needed. The rate of lipid oxidation depends on antioxidant source. The rosemary essential oil proved to be more efficient in preventing lipid oxidation of minced gilthead sea bream muscle than oregano essential oil.     

The effects of stabilised extracts of sage and oregano on the oxidation of salad dressings

The antioxidative activity of sage and oregano either dissolved in ethanol or homogenised with olive oil as a carrier was evaluated in salad dressings. These samples were stored in the dark at ambient temperature and at 40 °C, and with light exposure at ambient temperature. Sage and oregano extracts were encapsulated in liposomes by ultrasonification or microfluidisation, and their structures confirmed by microscopic examination and dye-marker carboxyfluorescein. The antioxidant effect of these preparations was evaluated in salad dressings during storage in the dark at ambient temperature, at 40 °C and at 60 °C. The oxidation process was followed by measuring the formation of conjugated diene hydroperoxides as primary and hexanal as secondary oxidation products, as well as changes in the compositions of fatty acids and tocopherols. Oregano and sage extracts homogenised with olive oil as a carrier showed higher antioxidative effects than these extracts dissolved in ethanol during storage in the dark at ambient temperature and at 40 °C. Exposure of salad dressings to light changed the antioxidative effect of plant extracts into a pro-oxidative effect. The preparation of liposomes by microfluidisation showed higher encapsulation efficiency and more homogeneous vesicles than liposomes prepared by ultrasonification. Sage liposomes prepared by micofluidisation showed high antioxidative effects similar to butylated hydroxytoluene liposomes in salad dressings during storage in the dark at ambient temperature and at 40 °C.     

迷迭香提取物对油条煎炸过程中菜籽油品质的影响

比较不同添加量（0.00%、0.005%、0.10%、0.02%、0.04%和0.07%）迷迭香提物（Rosemary Extract,RE）的菜籽油在煎炸过程中酸价、过氧化值、p-茴香胺值、共轭二烯值和共轭三烯值、极性组分含量和脂肪酸组成的变化和对反式脂肪酸（Transfatty acids,TFAs）生成情况的影响,并以0.02%的抗氧化剂叔丁基对苯二酚（tert-Butylhydroquinone,TBHQ）作为对照,考察迷迭香提物在煎炸过程中的抗氧化性能。结果表明,煎炸14 h时,空白油样和添加0.005%、0.10%、0.02%、0.04%和0.07% RE、0.02% TBHQ的酸价从煎炸初始的0.08±0.01、0.09±0.01、0.12±0.01、0.11±0.01、0.11±0.01、0.12±0.01、0.09±0.02 mg/g分别上升至0.75±0.03、0.68±0.04、0.65±0.06、0.64±0.01、0.62±0.01、0.58±0.02、0.64±0.01 mg/g,p-茴香胺值从1.90±0.10分别上升至201.50±1.04、159.73±0.40、165.67±0.51、156.53±0.23、166.57±0.23、157.50±0.40、163.53±0.55,共轭二烯值从5.81±0.03分别上升至32.34±0.01、26.65±0.14、23.06±0.12、23.68±0.63、19.49±0.52、21.06±0.02、22.94±0.11,共轭三烯值从0.87±0.01分别上升至5.30±0.01、4.51±0.07、4.40±0.08、4.99±0.01、4.93±0.03、4.00±0.01、4.30±0.04,煎炸14 h时,空白组煎炸油和TBHQ组煎炸油极性组分含量分别为（30.80±0.44）%和（30.63±0.42）%,添加0.07% RE的煎炸油极性组分含量最低,为（26.47±0.21）%。与空白组相比,添加RE对于菜籽油在煎炸过程中不饱和脂肪酸含量的降低有抑制作用。此外,添加0.07% RE对TFAs的抑制率达到17.39%,高于TBHQ的2.61%。研究表明迷迭香提物作为一种天然的抗氧化剂在煎炸油领域中具有广泛的应用前景。     

Stability of α-, γ-, or δ-Tocopherol during Soybean Oil Oxidation

ABSTRACT:  The decomposition of α-, γ-, or δ-tocopherol in soybean oil during 24 d of storage at 50 °C was determined by high performance liquid chromatography (HPLC). The initial contents of α-, γ-, and δ-tocopherol in soybean oil were 53, 750, and 268 ppm, respectively. The degradation rates of α-, γ-, and δ-tocopherol for the first 10 d were 5.6%, 1.2, and 0.5% per day, respectively. The α-tocopherol was completely destroyed in 16 d. The destructions of γ- and δ-tocopherol were 28% and 17% after 24 d. The induction period of soybean oil determined by headspace oxygen, conjugated diene, and peroxide value was 8 d. As the degradations of α-, γ-, and δ-tocopherol increased, the headspace oxygen disappearance, conjugated diene formation, and peroxide value of soybean oil increased. The correlation coefficient between the degradation of tocopherols and the oxidation of soybean oil was about 0.95. The degradation of tocopherols in soybean oil during storage was due to the oxidation.     

Individual and Combined Use of Rosemary and Origanum in Soybean Oil as Natural Antioxidants

Dried rosemary and origanum were added to soybean oil, individually and in combination, to determine their effect on the oxidation stability of soybean oil. Samples were stored at two different temperatures (60°C and room temperature) and oxidation was determined by peroxide value and conjugated diene value. The treated soybean oil samples showed evidence of antioxidant activity at 60°C and at room temperature. Furthermore, it was observed that the herbs stored under room temperature had a higher activity compared to those stored at 60°C.     

Effects of Sesame Oil Addition to Soybean Oil During Frying on the Lipid Oxidative Stability and Antioxidants Contents of the Fried Products During Storage in the Dark

ABSTRACT: Effects of sesame oil addition to soybean oil during frying on the lipid oxidative stability and antioxidants contents of fried products during storage in the dark were studied. Flour dough pieces (2 cm × 2 cm × 0.1 cm) were fried at 160 °C for 1 min in sesame oil-added soybean oil. Concentrations of sesame oil in the frying oil were 0%, 10%, and 20% by volume. Fried products were put into a glass bottle, and the bottles were tightly sealed and stored at 60 °C in the dark for 18 d. Lipid oxidation of fried products was determined by fatty acid composition changes and conjugated dienoic acid (CDA) and p -anisidine (PA) values. Tocopherols and lignan compounds in the fried products were determined by high-performance liquid chromatography. Relative content of linolenic acid decreased, and CDA and PA values increased during storage of the fried products in the dark. Fatty acid composition change and CDA and PA values during storage were lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil. The results clearly showed that addition of roasted sesame oil to soybean oil at 10% and 20% during frying decreased the lipid oxidation of fried products during storage in the dark for 18 d by extension of induction period and decrease in decomposition of oxidized lipids. Fried products contained 134 to 267 ppm tocopherols and 0 to 148 ppm lignans before storage; however, their contents decreased during storage in the dark. Lignan compounds were more stable than tocopherols, and the rate of tocopherols degradation was lower in the products fried in sesame oil-added soybean oil than in the products fried in soybean oil without sesame oil, which could be because of protection of tocopherols from degradation by lignan compounds.     

Lipid oxidation-related characteristics of gim bugak (Korean fried cuisine with <Emphasis Type="Italic">Porphyra</Emphasis>) affected by frying oil

The effect of frying oil on the lipid oxidation, antioxidants, and in vitro antioxidant activity of gim bugak was studied. Bugak was prepared by pan-frying at 180 °C in unroasted sesame, soybean, extra virgin olive, or palm oil. The degree of lipid oxidation based on conjugated dienoic acid and p-anisidine values was higher in the bugak fried in soybean or sesame oil with high contents of polyunsaturated fatty acids and tocopherols. However, the oil oxidation was lower in olive and palm oils, which showed higher degradation of tocopherols and polyphenols than in sesame or soybean oil during frying. Although the bugak fried in palm oil contained less antioxidants than that fried in soybean or sesame oil, the in vitro antioxidant activity was not different (p > 0.05). Results suggest that palm oil can replace unroasted sesame oil for the preparation of gim bugak with improved lipid oxidative stability and health functionality.     

Effects of storage conditions on oxidative stability of soybean oil

Soybean oil in the presence or absence of 200 µg g^?1 tert‐butyl hydroquinone (TBHQ) was subjected to accelerated oxidative storage at 60 °C for 10 days or stored at room temperature for 12 months. Tocopherol contents of the oil decreased, whereas the headspace volatiles and peroxide values (PV) increased as the storage time increased. During accelerated storage, TBHQ was effective in retarding the formation of hydroperoxides and headspace volatiles in the oil. TBHQ also protected tocopherols, especially α‐tocopherol, from oxidation. During long‐term room‐temperature (LTRT) storage, the changes in PV between the oils with and without TBHQ were similar, but the oil with TBHQ had lower headspace volatile contents than that without TBHQ. Headspace volatile analysis was more suitable than PV measurement for predicting the oxidative stability of soybean oil during LTRT storage. The contents of hexanal or (E)‐2‐heptenal in the oil at 1–5 days of accelerated storage could be used to predict those of the corresponding compound in the oil at 0–4 weeks of LTRT storage. Copyright © 2005 Society of Chemical Industry     

Oxidative Stability of ω3-rich Camelina Oil and Camelina Oil-based Spread Compared with Plant and Fish Oils and Sunflower Spread

ABSTRACT: The oxidative stability of ω3‐rich oil from Camelina sativa and the storage stability of a camelina oil‐based spread were evaluated. Camelina oil was more stable than fish oil and linseed oil, but less stable than sunflower, corn, sesame, and olive oils, indicated by measuring peroxide values (PV), ρ‐anisidine values (AV), total oxidation values (Totox), thiobarbituric acid reactive substances (TBARS), conjugated diene levels (CD), and conjugated triene levels (CT) during storage at 65 °C for 16 d. The camelina oil‐based spread had higher PV, AV, Totox, TBARS, CD, and CT than the sunflower spread but maintained adequate sensory quality for 16 wk of storage at 4 °C or 8 °C.     

Characterisation of phenolic compounds of Inca muña (Clinopodium bolivianum) leaves and the feasibility of their application to improve the oxidative stability of soybean oil during frying

Phenolic compounds from Inca muña leaves were, for the first time, qualitatively and quantitatively characterised. The main phenolic compounds encountered corresponded to flavanones, followed by flavones and hydroxycinnamic acid derivatives. Fractionation of Inca muña phenolic compounds revealed an ethyl acetate fraction (EaF) rich in phenolics and antioxidant activity. This EaF proved to be an efficient source of natural antioxidants for use against soybean oil oxidation during frying. Differential scanning calorimetry revealed higher induction periods for 600 ppm of EaF compared to 200 ppm of TBHQ and a negative control (no antioxidant added). During frying at ∼180 °C, 600 ppm of EaF showed the highest efficacy against oil oxidation in terms of p-anisidine values, conjugated dienes and trienes and polar compounds compared to 200 ppm of TBHQ and negative control. This study provides strong evidence for the antioxidant potential of Inca muña EaF phenolics against soybean oil oxidation. It suggests the possibility of incorporating these natural antioxidants from Inca muña leaves for use by the food industry.     

Effect of plant extracts on the oxidative stability of sunflower oil and emulsion

The antioxidative activities of six plant extracts (catnip, hyssop, lemon balm, oregano, sage and thyme) were evaluated in sunflower oil and its 20% oil-in-water emulsion in the dark at 60°C. The oxidation process was followed by measuring the formation of primary (conjugated diene hydroperoxides) and secondary (volatile compounds) oxidation products. Sage extracts (600 and 1200 ppm) effectively inhibited the formation of conjugated dienes and volatile compounds (hexanal and pentanal) in oil and emulsion and showed the highest antioxidative activity compared with 300 ppm BHT. Thyme and lemon balm extracts inhibited hexanal generation more than formation of conjugated dienes in both oil and emulsion. Oregano extract was more active in oil than in emulsion. Catnip and hyssop extracts (600 ppm) showed prooxidative action to sunflower oil at 60°C. These two extracts increased the formation of conjugated dienes compared with the control oil. In emulsions, catnip extract (600 ppm) was active and significantly inhibited the formation of conjugated dienes more than BHT (300 ppm) during additional incubation.     

Tocopherol Quantification by HPLC in Pecans and Relationship to Kernel Quality during Storage

Changes in tocopherols were followed in Stuart, Desirable and Schley cultivars during storage at 23.9°C and 60-70% RH and 0.6°C and 75% RH for 12 mo. Quality changes in the pecans were monitored using Hunter color measurements and conjugated diene measurement. α-, β-,γ- and 8-tocopherols were found in the three cultivars and γ-tocopherol was the primary form in each. Decreases of γ- and total tocopherols and L, hue angle and saturation index values were observed for pecans stored at 23.9°C (P < 0.05). Positive correlations (P < 0.05) were found between γ- and total tocopherols and Hunter color values for samples stored at 23.9°C. Conjugated diene levels did not correlate with tocopherol levels and Hunter values (P < 0.05). Pecans could be stored at 0.6°C and 75% RH for 12 mo without changes in kernel color, oil quality, tocopherols or conjugated diene levels.     

Oxidative and thermal stabilities of genetically modified high oleic sunflower oil

The oxidative and thermal stabilities of genetically modified high oleic sunflower oil (87% oleic acid) were compared with those of regular sunflower (17% oleic acid), soybean, corn, and peanut oils during storage at 55 °C and simulated deep fat frying at 185 °C. Oxidative stability was evaluated by measuring the oxygen content and volatile compounds in the sample bottle headspace and peroxide value. The coefficient variations (CVs) for volatile compound, headspace oxygen, and peroxide value analyses were 2.02%, 1.41%, and 3.18%, respectively. The oxidative stability of high oleic sunflower oil was greater than those of regular sunflower and soybean oil (P < 0.05) and as good as those of corn and peanut oils (P > 0.05). The thermal stabilities of oils during deep fat frying were evaluated by measuring the infrared absorption at 2.9 μm and conjugated diene content. The CV of conjugated diene content was 1.07%. Infrared and conjugated diene results showed that the high oleic sunflower oil had greater thermal stability than had regular sunflower, soybean, corn, and peanut oils (P < 0.05). The genetically modified high oleic sunflower oil, with 5.5% linoleic acid, had better oxidative and thermal stabilities than had the regular sunflower oil with 71.6% linoleic acid.     

油莎豆油的高温煎炸稳定性

以油莎豆油为研究对象,以大豆油为对照,选择过氧化值、p-茴香胺值、共轭二烯含量、共轭三烯含量为评价指标,考察高温煎炸条件下油莎豆油的稳定性,同时通过傅里叶变换红外光谱表征高温煎炸后油莎豆油结构的变化。结果表明：通过比较煎炸次数与过氧化值的关系,油莎豆油的煎炸稳定性略优于大豆油;两种油脂的p-茴香胺值均随煎炸次数增加而增大,大豆油的p-茴香胺值高于油莎豆油,大豆油与油莎豆油的p-茴香胺值与煎炸次数呈明显的相关性,相关系数分别为0982 8和0.988 2;随煎炸次数增加,大豆油中共轭二烯、共轭三烯含量均高于油莎豆油,因此油莎豆油的煎炸稳定性高于大豆油。红外光谱结果表明高温煎炸破坏了两种油脂的不饱和脂肪酸结构。     

Inhibition of lipid oxidation in fried chips and cookies by Majorana syriaca

This study evaluates the antioxidant effectiveness of a natural extract obtained from Majorana syriaca in fried and baked foods. Majorana syriaca was extracted with ethyl acetate (yield 129 g kg^?1, dry basis) and the extract was added to refined corn oil at a concentration of 500 ppm. The oil was used in deep frying of potato chips at 185 °C and in making baked cookies. Potato chips and cookies were further subjected to accelerated oxidation at 70 °C. The protection of the frying oil was moderate as indicated by the polar content and conjugated dienes (CD) measurements, however, a remarkable improvement of the oxidative stability of the fried chips was observed through the decrease of peroxide value (PV) and CD by 59–72% and 51–79%, respectively, compared to samples with no additive. Also, the PV and CD of cookies decreased by 79% and 72%, respectively.     

Anti‐radical power gives insight into early lipid oxidation events during frying

The aim of this research was to use anti‐radical power (ARP) to study early lipid oxidation events during frying. The 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH?) test was used to determine the ARP. As oil does not dissolve completely in methanol, which is generally used for the DPPH? test, butanol was used instead. Changing the solvent did not influence the value of the ARP. The decrease of the ARP highly correlated with the increase of the peroxide value for soybean oil heated at 110 °C (R² = 0.99). Sensory analysis showed that rancidity of soybean oil and frying oil, heated at 180 °C, was perceived before the ARP decreased. Once the oil was perceived as rancid, the intensity of rancidity did not change significantly upon further heating. The ARP of soybean oil was found to decrease faster at 110 °C than at 180 °C, suggesting different mechanisms of radical formation. The total polar compounds of frying oil in which French fries were fried did not differ significantly from frying oil that was heated alone. However, frying of French fries caused more hydrolysis of the oil, while the ARP decreased faster when the oil was heated alone. Copyright © 2006 Society of Chemical Industry     

High-Temperature Natural Antioxidant Improves Soy Oil for Frying

ABSTRACT:  The objectives of this study were to determine the frying stability of soybean oil (SBO) treated with a natural citric acid-based antioxidant, EPT-OILShield™ able to withstand high temperatures and to establish the oxidative stability of food fried in the treated oil. Soybean oil with 0.05% and 0.5% EPT-OILShield and an untreated control SBO were used for intermittent batch frying of tortilla chips at 180 °C for up to 65 h. Oil frying stability was measured by free fatty acids (FFA) and total polar compounds (TPC). Chips were aged for up to 4 mo at 25 °C and evaluated for rancid flavor by a 15-member, trained, experienced analytical sensory panel and for hexanal content as an indicator of oxidation. Oil with 0.05% EPT-OILShield had significantly less FFA and TPC than the control. The effect of EPT-OILShield was apparently retained in aged chips because hexanal levels were significantly lower in chips fried in oil with 0.05% EPT-OILShield than in chips fried in the control. Tortilla chips fried in the control were rancid after 2 mo at 25 °C at sampling times evaluated from 25 to 65 h; however, chips fried in oil with 0.05% EPT-OILShield and used for 65 h were described as only slightly rancid after 4 mo. Gamma tocopherol levels were significantly higher in the chips fried in the oil with 0.05% EPT-OILShield than in the control, helping to inhibit oxidation in the tortilla chips during storage.     

Changes in oil and potato chips during frying

The effect of frying of potato chips (batch processing during 12 h) on the chemical characteristics and fatty acid composition of the used oil were determined. Samples of the fried oil and potato chips were taken at various time periods. The volatile carbonyl compounds of the aroma concentrate of each sample were isolated and their oxime derevatives were prepared and subsequently estimated by UV absorption for the total oximes and conjugated diene carbonyl oximes. The development of the volatile carbonyl compounds in both frying oil and fried potato chips was increased on continued frying. Concerning the frying oil this increase was found to be in coincident with the decrease in the linoleic and linolenic acid percent.