Comparison of Oxidative Stability among Edible Oils under Continuous Frying Conditions

The stability of camellia oil (saturated fatty acid: monounsaturated fatty acid: polyunsaturated fatty acid = 1:7:1) after frying potatoes was compared with palm oil (saturated fatty acid: monounsaturated fatty acid: polyunsaturated fatty acid = 4:4:1) and peanut oil (saturated fatty acid: monounsaturated fatty acid: polyunsaturated fatty acid = 2:4:4). Oil samples were evaluated for acid value, iodine value, peroxide value, p-anisidine value, total oxidation value, tocopherols content, and fatty acids composition. There was the least change in fatty acid composition in camellia oil among the three edible oils. The α-tocopherol was more vulnerable to heat degradation than γ-tocopherol and δ-tocopherol, and α-tocopherol was completely degraded before the whole frying process was done for palm and peanut oils. The oxidative stabilities of the three edible oils were in the order of camellia oil > palm oil > peanut oil. The oxidative stability was mainly determined by the calculated oxidizability value related to fatty acid composition, and when calculated oxidizability values were similar, the tocopherol contents of edible oils would be a key factor in affecting their oxidative stabilities.     

Physicochemical properties and oxidative stabilities of mealworm (<Emphasis Type="Italic">Tenebrio molitor</Emphasis>) oils under different roasting conditions

Physicochemical properties and oxidative stabilities of mealworm (Tenebrio molitor) oils under different roasting conditions were investigated. Oils were extracted using n-hexane from mealworms roasted at 200°C for 0, 5, 10, and 15 min and physicochemical properties and oxidative stabilities of oils were analyzed. Roasting increased the color intensity and the oleic acid and δ-tocopherol contents, but decreased linoleic acid, and α- and γ-tocopherol contents. An improvement in oxidative stability was observed in roasted mealworm oils, demonstrated by induction time and peroxide values. Mealworm oil contained abundant essential fatty acids and exhibited a superior oxidative stability.     

Antioxidants in lipid foods and their impact on food quality

This paper reviews the antioxidant properties of tocopherols and ascorbic acid in edible oils, and the impact of interfacial phenomena on their activities in emulsions and the effects of edible oil processing. Tocopherols are the most important natural antioxidants found in vegetable oil-derived foods. These antioxidants can interrupt lipid autoxidation by interfering with either the chain propagation or the decomposition processes. α-Tocopherol at high concentrations inhibits hydroperoxide decomposition but promotes hydroperoxide formation. The effect of antioxidants in inhibiting hydroperoxide decomposition may thus be critical in preserving food quality by reducing rancidity due to aldehyde formation. Ascorbic acid can regenerate α-tocopherol, inactivate metal initiators and reduce hydroperoxides. The activity of natural antioxidants is greatly affected by complex interfacial phenomena in emulsions and multi-component foods. In an oil-in-water emulsion system, the lipophilic antioxidants α-tocopherol and ascorbyl palmitate are more effective than in bulk oil, while the opposite trend is found for the hydrophilic antioxidants Trolox and ascorbic acid. The methodology to evaluate natural antioxidants must be carefully interpreted depending on whether oxidation is carried out in bulk oils or in emulsions, and what method is used to measure lipid oxidation.     

FATE OF THE SYNERGISTIC ANTIOXIDANT SYSTEM ASCORBIC ACID, LECITHIN, AND TOCOPHEROL IN MAYONNAISE: PARTITION OF ASCORBIC ACID

The distribution of ascorbic acid between the lipid and aqueous phase was investigated in mayonnaises enriched with fish oil containing a synergistic antioxidant mixture of ascorbic acid, lecithin and γ-tocopherol, i.e., the A/L/T system (Löliger and Saucy 1989). The ascorbic acid was found to be located in the aqueous phase indicating that the A/L/T system broke down in mayonnaises. Based on the hypothesis that synergistic antioxidant action between ascorbic acid, lecithin and tocopherol requires that the three components are in close assembly, the results offer an explanation as to why the A/L/T system does not function antioxidatively in mayonnaises.     

Interactions between tocopherols,tocotrienols and carotenoids during autoxidation of mixed palm olein and fish oil

Electron spin resonance (ESR) and spin trapping detection of radical formation showed that the oxidative stability of palm olein/fish oil mixtures increased with the amount of palm olein. Mixtures with red palm olein were less stable than were mixtures with yellow palm olein. Addition of ascorbyl palmitate and citric acid gave further reduction of radical formation, whereas no effect was observed by adding lecithins. Storage of palm olein/fish oil mixtures (4:1) at 30 °C confirmed that red palm olein mixtures were less stable than were yellow palm olein mixtures. Ascorbyl palmitate together with citric acid improved the stability in both cases. The concentrations of α-tocopherol and α-tocotrienol decreased during storage, whereas β-, γ-, and δ-tocotrienols were unaffected. Ascorbyl palmitate reduced the losses of α-tocopherol and α-tocotrienol. The rate of loss of carotenoids was independent of the presence of fish oil and, except for an initial fast drop, also of the presence of ascorbyl palmitate.     

The anti-inflammatory effect of lycopene complements the antioxidant action of ascorbic acid and α-tocopherol

Tomato foods contain bioactive compounds, such as lycopene, ascorbic acid and α-tocopherol, which are assumed to show synergistic effects. The aim of the study was to investigate this presumed synergy. The effect on lipid peroxidation and inflammation was assessed. Lipid peroxidation was effectively inhibited by combinations of the compounds compared to the single compounds. Synergy between the combination of ascorbic acid and α-tocopherol was confirmed. Lycopene on its own effectively reduced inflammation by inhibiting the release of TNF-α and stimulating IL-10 production. The combination of lycopene, ascorbic acid and α-tocopherol tended to display a synergistic interaction on IL-10 production. Our observations highlight that lycopene mitigates inflammation, whereas ascorbic acid and α-tocopherol efficiently protect against lipid peroxidation. Both activities are complementary since they diminish the process of inflammation differently on different levels. In relation to health, this is an added value of fruit and vegetables such as tomato products that contain complementary bio-active compounds.     

Natural Antioxidants for Preventing Color Loss in Stored Paprika

Oxidative carotenoid degradation causes paprika color loss during storage. Ethoxyquin, a synthetic antioxidant, is used in the spice industry to prevent carotenoid loss during postharvest handling. However, ethoxyquin treated paprika is unacceptable for some markets and consumers. Naturally derived antioxidants, i.e., rosemary extracts, ascorbic acid, δ-tocopherol, and mixed tocopherols were tested as color protectants in two paprika cultivars. Extractable color, surface color and carotenoid concentrations were determined before storage and then monthly. After 4 mo storage at ambient temperature, the control treatment lost 63% of the initial extractable color, the δ-tocopherol treated samples lost 32%, and the ethoxyquin lost 6% color.     

Oxidative stability of Atlantic salmon (Salmo salar,L.) fillet enriched in α-, γ-, and δ-tocopherol through dietary supplementation

The purpose of this study was to examine the effect of dietary tocopherols on the oxidative stability of Atlantic salmon fillet. The fish were fed four diets supplemented with 150mg kg⁻¹ α-tocopherol and different combinations of γ- and δ-tocopherol (50 or 100mgkg⁻¹) for 10 months, slaughtered, and stored for 16 days on ice, or 48 weeks at −30 °C. Fillet concentrations of tocopherols at slaughter were 0.101 ± 0.001, 0.091 ± 0.004 and 0.025 ± 0.002 times feed concentration for α-, γ- and δ-tocopherol, respectively. Fillet α-tocopherol, but not γ- and δ-tocopherol, was moderately lowered during iced and frozen storage. The non-α-tocopherols protected the fillet against lipid oxidation in a dose-dependent manner during frozen storage, but appeared to act as prooxidants during storage on ice. It is concluded that α-tocopherol may be better suited than mixed tocopherols as a tool to optimize the oxidative stability of Atlantic salmon fillet.     

Fat Content Influences the Color, Lipid Oxidation, and Volatiles of Irradiated Ground Beef

ABSTRACT:  Ground beef with 10%, 15%, or 20% fat were added with none, 0.05% ascorbic acid + 0.01%α-tocopherol, or 0.05% ascorbic acid + 0.01%α-tocopherol + 0.01% sesamol, and irradiated at 0 or 2.5 kGy. The meat samples were displayed under fluorescent light for 14 d at 4 °C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined during storage. Irradiation increased lipid oxidation and total volatiles of ground beef regardless of fat contents. Ascorbic acid +α-tocopherol + sesamol treatment was the most effective in reducing lipid oxidation during storage. The production of ethanol in nonirradiated ground beef increased dramatically after 7 d of storage due to microbial growth. Total aldehydes and hexanal increased drastically in irradiated control over the storage period, but hexanal increased the most by irradiation.  L *-values was decreased by irradiation, but increased in all meat regardless of fat contents as storage period increased. Irradiation reduced the redness, but fat contents had no effect on the  a *-value of ground beef. Sesamol lowered, but ascorbic acid +α-tocopherol maintained the redness of irradiated beef up to 2 wk of storage. The yellowness of meat was significantly decreased by irradiation. The reducing power of ascorbic acid +α-tocopherol lasted for 3 d, after which ORP values increased. Irradiation increased CO production regardless of fat content in ground beef. In conclusion, up to 20% fat had no effect on the quality change of irradiated ground beef if ascorbic acid +α-tocopherol was added.     

Recovery and distribution of natural antioxidants (α-tocopherol,polyphenols and terpenic acids) after pan-frying of Mediterranean finfish in virgin olive oil

Samples of eight finfish representing the most popular fish species in Greece were pan-fried in virgin olive oil according to the Greek traditional culinary practice. Analyses for polyphenols, hydroxy pentacyclic triterpene acids (HPTA) and α-tocopherol were performed in the fresh and fried oils and fish. Polyphenols and HPTA were determined by GC/MS and α-tocopherol by HPLC. Nine polyphenols were determined in the frying oil samples; six of them were also found in fried fish. The terpenic acids oleanolic, maslinic and ursolic were also determined in frying oils and fried fish. No polyphenols and no HPTA were detectable in raw fish, while α-tocopherol was present in all samples. Besides water loss and oil absorption, pan frying caused the partial loss of all the antioxidants studied in the fried oils, as well as their enrichment in the fried fish. The overall retention of α-tocopherol in the fried oil and fish ranged from 30% to 80%, the respective values for polpyphenols and HPTA ranging between 51–87% and 46–88%. The polarity of the antioxidants studied, seems to affect to some extent their partition between the frying oil and the water-containing fish.     

不同产地南瓜籽油组成及氧化稳定性的差异

以我国8 个不同产地南瓜籽为原料,压榨制备南瓜籽油,对比分析不同南瓜籽油的组成和氧化稳定性。结果表明,南瓜籽油主要含有棕榈酸、硬脂酸、油酸、亚油酸4 种脂肪酸,不饱和脂肪酸含量占80.565%～84.964%,总酚含量为167.21～204.50 mg/kg,总甾醇含量为1 204.38～1 604.51 mg/kg,α-生育酚含量为25.7～58.7 mg/kg,γ-生育酚含量为1 839.8～2 728.3 mg/kg,δ-生育酚含量为248.8～518.7 mg/kg。Pearson双变量相关性分析表明,总酚与极性组分自由基清除能力有显著相关性（P＜0.05）,α-生育酚等油脂伴随物也发挥了一定的抗氧化作用。主成分分析和聚类分析的结果显示：不同产地的南瓜籽油功能性成分相似,由于含量差别显示出具有显著差异的2 个集群,甘肃省白银市产的南瓜籽油综合评分最高。本研究对南瓜籽资源的开发利用具有一定的指导意义。     

Effect of Antioxidant Application Methods on the Color, Lipid Oxidation, and Volatiles of Irradiated Ground Beef

ABSTRACT:  Four antioxidant treatments (none, 0.05% ascorbic acid, 0.01%α-tocopherol + 0.01% sesamol, and 0.05% ascorbic acid + 0.01%α-tocopherol + 0.01% sesamol) were applied to ground beef using either mixing or spraying method. The meat samples were placed on Styrofoam trays, irradiated at 0 or 2.5 kGy, and then stored for 7 d at 4 °C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined at 0, 3, and 7 d of storage. Irradiation increased lipid oxidation of ground beef with control and ascorbic acid treatments after 3 d of storage. α-Tocopherol + sesamol and ascorbic acid +α-tocopherol + sesamol treatments were effective in slowing down lipid oxidation in ground beef during storage regardless of application methods, but mixing was better than the spraying method. Irradiation lowered L *-value and a *-value of ground beef. Storage had no effect on lightness but redness decreased with storage. Ascorbic acid was the most effective in maintaining redness of ground beef followed by ascorbic acid +α-tocopherol + sesamol. Irradiation and storage reduced the b *-value of ground beef. Irradiation lowered ORP of ground beef regardless of antioxidants application methods, but ORP was lower in beef with mixing than spraying method. Beef sprayed with antioxidants produced more hydrocarbons and alcohols than the mixing application, but ascorbic acid +α-tocopherol + sesamol treatment was effective in reducing the amount of volatiles produced by irradiation. Therefore, mixing was better than the spraying method in preventing lipid oxidation and maintaining color of irradiated ground beef.     

Antioxidant Activity of Tocopherols and Ascorbic Acid

A study was made of the inhibitory effect of the antioxidants α-tocopherol, γ-tocopherol and ascorbic acid on the lipoxygenase catalyzed oxygenatior of linoleic acid. Gas chromatography was used to measure unchanged fatty acid after varying incubation periods. The effect of the antioxidants was also determined from the traditional rancidity parameters, peroxide value and thiobarbituric value.     

The antioxidative activity of RRR-α-tocopherol vs RRR-δ-tocopherol in combination with ascorbyl palmitate in cooked,minced turkey

RRR-α-tocopherol and RRR-δ-tocopheroI (100 or 200 ppm) had similar and significantly better antioxidative effects compared to ascorbyl palmitate (200 ppm) in turkey meat balls during storage at 5 °C for up to 9 days, as determined by measurement of thiobarbituric acid reactive substances (TBARS) and by static head space detection of hexanal. The antioxidative effect of α-tocopherol at 100 ppm was, measured as a reduction of head space hexanal, significantly enhanced by ascorbyl palmitate (200 ppm), resulting in a further 50% reduction compared to δ-tocopherol. At the 200-ppm level, only the antioxidative activity of α-tocopherol was enhanced significantly by ascorbyl palmitate (200 ppm), in contrast to the effect on the antioxidative activity of δ-tocopherol (200 ppm). The antioxidative activity obtained by α-tocopherol at the 100-ppm level in combination with ascorbyl palmitate (200 ppm) was similar to the effect obtained by α-tocopherol at the 200-ppm level in combination with ascorbyl palmitate (200 ppm) measured as head space hexanal. Ascorbyl palmitate was in all storage experiments depleted in the product at a rate which appeared to be independent of the presence of tocopherols. Of the tocopherol homologues, α-tocopherol was most affected by the presence of ascorbyl palmitate, and the concentration of α-tocopherol was found to decrease during storage in the absence of ascorbyl palmitate, in contrast to when ascorbyl palmitate was present. A similar effect of ascorbyl palmitate was less evident for δ-tocopherol and for γ-tocopherol in a natural mixture of the tocopherol homologues added to turkey meat balls.     

High performance liquid chromatography method for the simultaneous determination of α-, γ- and δ-tocopherol in vegetable oils in presence of hexadecyltrimethylammonium bromide/n-propanol in mobile phase

A rapid methodology by RP-HPLC, 10 min of total analysis time, for the analysis of α-, γ- and δ-tocopherol in vegetable oils, in presence of retinol, retinyl acetate and α-tocopherol acetate was developed. Hexadecyltrimethylammonium bromide 0.1 M/n-propanol 65% (v/v) are used as mobile phase. Tocopherols were detected using UV and fluorescence detection. The quantification limits for α-, γ- and δ-tocopherols were 0.28, 0.12 and 0.23 mg L⁻¹, respectively. The method yielded satisfactory results when it was applied to vegetable oils and thus, it is suitable for their quality control.     

ANTIOXIDANT EFFICACY OF EXTRACTS OF AN EDIBLE RED ALGA (GRATELOUPIA FILICINA) IN LINOLEIC ACID AND FISH OIL

The antioxidant activity of an extract of a marine red alga (Grateloupia filicina) was evaluated in linoleic acid and fish oil induct period oil at 65C. Oxidative stability of the oils was evaluated by employing peroxide value (PV), 2-thiobarbituric acid reactive substances (TBARS), conjugated diene (CD) and weight gain experiments. The algal extract was applied to linoleic acid and fish oil at 0.01, 0.03 and 0.05% and results were compared with those of commercial antioxidants such as butylated hydroxytoluene (BHT), butylated hydroxyanisol (BHA) and α-tocopherol at 0.01 %. Results indicated the ability of the alga extract to inhibit oxidation of linoleic acid and fish oil; at α 0.05%     

Prooxidant Activity of Oxidized α-Tocopherol in Vegetable Oils

ABSTRACT:  The effect of oxidized α-tocopherol on the oxidative stabilities of soybean, corn, safflower, and olive oils and the oxidation of oleic, linoleic, and linolenic acids were studied. The 0, 650, 1300, and 2600 ppm oxidized α-tocopherol were added to soybean, corn, safflower, and olive oils and 10000 ppm oxidized α-tocopherol to the mixture of oleic, linoleic, and linolenic acids. Samples in the gas-tight vials were stored in the dark for 6 or 35 d at 55 °C. The oxidative stabilities of oils were determined by headspace oxygen with GC and peroxide value. Fatty acids were determined by GC. As the concentration of oxidized α-tocopherol in soybean, corn, safflower, and olive oils increased, the depletion of headspace oxygen and the peroxide values of oils increased during storage. The prooxidant effects of oxidized α-tocopherol on soybean and corn oils with about 55% linoleic acid were greater than those on safflower and olive oils with about 12% linoleic acid, respectively ( P  < 0.05). The changes of fatty acids during storage showed that the oxidation ratios of oleic, linoleic, and linolenic acids were 1 : 2 : 3, 1 : 12 : 26, and 1 : 8 : 16 after 5, 30, and 35 d of storage, respectively. The oxidation of α-tocopherol in oil should be prevented and the oxidized α-tocopherol should be removed to improve the oxidative stability of oils.     

Influence of α-, γ-, and δ-tocopherol on the radiation induced formation of peroxides in rapeseed oil triacylglycerols

The effect of α-, γ-, and δ-tocopherols (enrichment: 1000 ppm) on the peroxide formation in rapeseed oil triacylglycerols (RSOTG) was evaluated. The oxidation process was initiated by gamma-irradiation with doses of 4 and 10 kGy. Whereas a pronounced antioxidant effect was observed for γ- and δ-tocopherol (sequence: δ- > γ-tocopherol), the inhibition extent of α-tocopherol was insignificant.     

Determination of antioxidant activity and antioxidant content in tomato varieties and evaluation of mutual interactions between antioxidants

Major antioxidants and antioxidant activity in eight varieties of tomatoes were determined. Hydrophilic and lipophilic antioxidant activity (HAA and LAA) was determined by the ABTS assay and ascorbic acid and carotenoid contents were determined by HPLC-DAD. The HAA has far more significant impact on total antioxidant activity (83%) as compared with LAA. HAA was increasing during all ripening stages and was strongly correlated with ascorbic acid content (r = 0.83). During the ripening the LAA was increasing till the III. stage of maturity and then decreased. The main carotenoids determined in the red-fruit tomatoes were lycopene, β-carotene and lutein. The content of lycopene has been increasing equally during the ripening. β-Carotene and lutein were intensively synthesized between the I. and II. stage of maturity. Among ascorbic acid, α-tocopherol, lycopene, β-carotene and lutein standards ascorbic acid was determined as the most efficient antioxidant followed by α-tocopherol and β-carotene. Antioxidant activity of ascorbic acid, α-tocopherol, β-carotene and lutein grew equally with increasing concentration, however lycopene was the most effective in its lowest concentration. The analysis of two-component mixtures showed significant synergism between lycopene-lutein, lycopene-β-carotene and α-tocopherol-β-carotene.     

咖啡豆烘焙过程中油脂脂肪酸组成、挥发性风味及活性成分的演变规律

以云南小粒种咖啡豆为试材,系统研究烘焙过程中咖啡油脂理化性质、脂肪酸组成、挥发性成分及活性成分的变化规律。结果表明：随着烘焙度加深,油脂色泽加深;酸价呈增加的趋势,由1.60 mg/g增至3.75 mg/g;碘值反之,由142.04 g/100 g降至83.12 mg/100 g;茴香胺值先增大后减少,其值在3.40～16.26之间;皂化值略有降低,但无显著差异;共鉴定出11 种脂肪酸,主要为亚油酸相对含量在43.06%～64.39%之间,其次为硬脂酸和棕榈酸相对含量在12.67%～27.55%之间,油酸相对含量为9.03%～17.20%;脂肪酸组成影响不明显,但各脂肪酸的含量存在一定差异;利用气相色谱-质谱从极浅度到法式重度的咖啡油脂样品中分别检出25、33、36、53、54、59、64 种和58 种挥发性成分,主要成分有呋喃类化合物、吡嗪类化合物、酮类化合物、吡咯类化合物等,其种类和含量均呈减小趋势;活性成分中咖啡豆醇、α-生育酚、γ-生育酚、δ-生育酚含量均减少;而总酚含量不断增加,由7.75 mg/100 g升至15.96 mg/100 g。本研究结果可为咖啡精深加工及资源高值化利用提供理论依据和技术支撑。