α-, γ- and δ-Tocopherol Effects on Chlorophyll Photosensitized Oxidation of Soybean Oil

The effects of 0, 1.0, 2.0 and 4.0 (x 10^?3 M) α-, γ- or δ-tocopherol on chlorophyll b photosensitized oxidation of soybean oil in methylene chloride were studied by peroxide values and headspace oxygen. As concentrations of tocopherols increased, peroxide values decreased and headspace oxygen increased (P < 0.05). At 1.0 × 10^?3 M, α-tocopherol showed highest antioxidant effect, γ-tocopherol second and then δ-tocopherol. α- and -γ-Tocopherols had similar effects and δ-tocopherol had lower effect at 2.0 × 10^?3 M (P < 0.05). However, the three tocopherols were not different (P > 0.05) at 4.0 × 10^?3 M. α-Tocopherol quenched singlet oxygen to reduce the photosensitized oxidation of oil. The quenching rate constants of α-tocopherol were 2.7 × 10⁷M^?1sec^?1 by peroxide value and 2.6 × 10⁷ M^?1sec^?1 by headspace oxygen.     

Storage Stability of α-Tocopherol in a Dehydrated Model Food System Containing Methyl Linoleate

The storage stability of α-tocopherol in a dehydrated model food system containing methyl linoleate was evaluated. The degradation rate of α-tocopherol was best described by zero order kinetics with rates significantly greater than 0 (p≤0.002), correlation coefficients (|R|)≤0.88 and standard deviations from 4–13% of the reported rate constants. The zero order rate constants were dependent on the initial α-tocopherol concentrationn, indicating that the concentration of α-tocopherol and unknown reactant(s) does affect the storage stability of α-tocopherol. The storage parameters of water activity, storage container oxygen content, and storage temperature affected the rate of α-tocopherol loss indicating that these parameters must be controlled to maximize α-tocopherol storage stability.     

Dietary Pigmentation and Deposition of α-Tocopherol and Carotenoids in Rainbow Trout Muscle and Liver Tissue

Rainbow trout (Oncorhynchus mykiss) were fed diets supplemented with canthaxanthin, oleoresin paprika and α-tocopherol. Canthaxanthin was more efficiently absorbed (3.8–7.9 mg/kg) in the flesh of rainbow trout than the paprika carotenoids (2.4–3.1 mg/kg). With increased pigmentation, decrease in lightness (L*) and hue angle, and increase in redness (a*) of the muscle were observed. Canthaxanthin produced more desirable reddish-pink color. Deposition of α-tocopherol in liver and muscle tissue increased with increase in dietary α-tocopheryl acetate. Fish receiving lower α-tocopheryl acetate reached maximum deposition levels earlier than those fed higher levels. There was no effect of α-tocopherol and carotenoid levels on muscle fatty acid composition.     

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.     

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.     

Effects of Dietary Oils and α-Tocopherol Supplementation on Membranal Lipid Oxidation in Broiler Meat

The effects of different dietary oils and α-tocopherol on the fatty acid composition of mitochondrial and microsomal lipids of broiler muscle and their lability to NADPH-induced peroxidation were investigated. Fatty acid composition of both neutral lipids and phospholipids of mitochondria and microsomes was influenced by dietary oil composition. Supplementation of the diet with α-tocopherol only appeared to increase the α-tocophcrol concentration in the microsomal membranes in the dark meat. The rate of NADPH-induced lipid peroxidation in microsomes and mitochondria was dependent primarily on the fatty acid composition of the membrane lipids, and, to a lesser extent, on the α-tocopherol content.     

α-Tocopherol and Ascorbate Delay Oxymyoglobin and Phospholipid Oxidation In Vitro

An oxymyoglobin liposome model was used to study the effects of α-tocopherol and/or ascorbate upon oxymyoglobin and lipid oxidation. Both oxidations were delayed (P<0.05) by increased concentrations of α-tocopherol alone and α-tocopherol/ascorbate relative to controls. The 14 μ Mα-tocopherol/140 μM ascorbate treatment resulted in greatest delay in both oxymyoglobin and lipid oxidation. Ascorbate alone delayed oxymyoglobin oxidation; effectiveness diminished as ascorbate increased. Ascorbate showed a prooxidant effect toward lipid oxidation which was unchanged in the presence of EDTA. Results support the hypothesis that α-tocopherol retards lipid oxidation directly and OxyMb oxidation indirectly.     

Dietary α-Tocopheryl Acetate Contributes to Lipid Stability in Cooked Beef

Lipid oxidation was investigated in cooked gluteus medius from Holstein steers fed diets including four levels of α-tocopheryl acetate (0, 250, 500 and 2,000 mg/steer daily) for 42 or 126 days. Alpha-tocopherol (vitamin E) concentrations increased in fresh and cooked muscle due to level and duration of supplementation (P<0.01). Cooking did not affect α-tocopherol concentration in the muscle. Dietary α-tocopheryl acetate delayed (P<0.01) accumulation of lipid oxidation products in cooked muscle during 6 days of display at 4°. Daily supplementation of 500 mg α-tocopheryl acetate for 126 days resulted in 3.4 μg α-tocopherol/g cooked gluteus medius.     

Effects of α-, γ-, and δ-Tocopherols on Oxidative Stability of Soybean Oil

The effectts of 0, 100, 250, 500 and 1000 ppm of α-, γ-, or δ-tocopherol on oxidative stability of purified soybean oil in the dark at 55°C were studied. We measured peroxide value and headspace oxygen consumption in the samples. Purified soybean oil was prepared by liquid column chromatography. Tocopherols acted as antioxidants or prooxidants depending on their concentration. Optimum concentrations of α -, γ -, and δ– tocopherols to increase oxidative stability was 100, 250 and 500 ppm, respectively. The tocopherols had significant prooxidant effect (P < 0.05) at higher concentrations above this.     

Effect of dietary Vitamin E on the stability of raw and cooked pork

Experiments were designed to investigate the effects of dietary α-tocopherol supplementation for 2 weeks prior to slaughter on plasma and muscle α-tocopherol levels and on the oxidative stability of raw and cooked pig muscle during refrigerated storage at 4°C. Plasma and muscle α-tocopherol levels of the pigs on the α-tocopherol supplemented diet (200 mg α-tocopherol acetate/kg feed) were ～2·5-fold higher than those of the pigs on the control diet (30 mg α-tocopherol acetate/kg feed). Dietary supplementation with α-tocopherol significantly (p < 0·01) improved the oxidative stability of both raw and cooked muscle after storage at 4°C for up to 8 days. α-Tocopherol stabilized the membrane-bound lipids against metmyoglobin/H(2)O(2)-initiated oxidation and also significantly (p < 0·05) improved the oxidative stability of rendered fat.     

Oxymyoglobin and Lipid Oxidation in Phosphatidylcholine Liposomes Retarded by α-tocopherol and β-carotene

An n-3 fatty acid-constructed oxymyoglobin liposome model was used to study the effects of 10 μM α-tocopherol and/or various concentrations of β-carotene on oxymyoglobin and lipid oxidation. Oxidation was delayed by α-tocopherol or β-carotene treatments alone (p < 0.05). β-Carotene at 1.5 μM and 2μM caused greater delay in oxymyoglobin oxidation than α-tocopherol (p < 0.05). For lipid oxidation inhibition, 2 μM β-carotene was similar in effect to α-tocopherol. With α-tocopherol plus 1.5 or 2 μM β-carotene, greater oxidation delaying effect resulted for both oxymyoglobin and lipid oxidations than with 1.5 or 2 μM β-carotene treatment alone (p < 0.05).     

Stability of Cholesterol and Paprika Carotenoids in Egg Powders as Influenced by Dietary and Processing Treatments

The effects of dietary α-tocopherol and/or oleoresin paprika (OP) on cholesterol and carotenoid stability in egg powders during spray drying and subsequent storage were investigated. Cholesterol oxidation and loss of carotenoids in eggs dried with a direct gas-fired spray dryer were greater ( P< 0·05) than in eggs dried using an indirect (electric) heating system. Dietary supplementation of α-tocopherol acetate (200 mg kg⁻¹ feed) significantly increased ( P< 0·01) the oxidative stability of cholesterol and carotenoids in eggs dried with the direct heating system. Supplementation of OP (7·5 μg g⁻¹ egg lipids) through diet or by direct addition to liquid eggs did not affect the formation of cholesterol oxidation products (COPS) during storage. However, increased concentrations of OP in liquid eggs (15 and 30 μg g⁻¹ lipids) suppressed the formation of COPS during processing and subsequent storage.     

Quenching Mechanisms and Kinetics of α-Tocopherol and β-Carotene on the Photosensitizing Effect of Synthetic Food Colorant FD&C Red No. 3

ABSTRACT: Effects of FD&C Red No. 40, Red No. 3, Yellow No. 5, Yellow No. 6, Green No. 3, Blue No. 1 and Blue No. 2 on 0.03M soybean oil oxidation in acetone at 25 °C under light were studied by measuring headspace oxygen depletion. As Red No. 3 increased from 0 to 5, 20, 100 and 200 ppm, the headspace oxygen was reduced by 2 to 70, 73, 77 and 77%, respectively, for 4 h. Only Red No. 3 acted as a photosensitizer to produce singlet oxygen in the oil. The quenching rates of α-tocopherol and β-carotene for the singlet oxygen by Red No.3 were 4.1 × 10⁷ M⁻¹s⁻¹ and 7.3 × 10⁹ M⁻¹s⁻¹, respectively. When β-carotene was below 1.86 × 10⁻⁶ M, β-carotene quenched singlet oxygen, but it quenched both singlet oxygen and Red No. 3 at or above 3.72 × 10⁻⁶ M. However, α-tocopherol quenched singlet oxygen only.     

Inhibition of N-Nitrosopyrrolidine in Dry Cured Bacon by α-Tocopherol-Coated Salt Systems

Dry cured bacon was made under carefully controlled processing conditions in a pilot plant study using α-tocopherol-coated salt as part of the dry cure. Approximately, a 96% reduction in N-nitrosopyrrolidine (NPYR) levels in the fried bacon was achieved with an ingoing α-tocopherol level of 500 mg/kg. NPYR levels in the cookout fat were reduced approximately 92% using the same level of α-tocopherol. Bacon, prepared by a small scale commercial operation, also contained reduced levels of NPYR when processed with α-tocopherol-coated salt, despite high levels (>100 mg/kg) of residual sodium nitrite in the finished bacon. Results comparing effectiveness of α-tocopherol and mixed tocopherols as nitrosamine blocking agents were inconclusive. Although, α-tocopherol appeared to be more effective as a blocking agent (91% versus 73% inhibition of NPYR), the difference in percent inhibition achieved could possibly be attributed to apparently lower levels of residual mixed tocopherols in the finished bacon.     

Influence of dietary α-tocopheryl acetate supplementation of pigs on oxidative deterioration and weight loss in sliced dry-cured ham

The effect of feeding high levels of α-tocopherol to pigs on the susceptibility to oxidative deterioration and weight loss in dry cured hams was investigated. The α-tocopherol concentration in thigh muscle from pigs fed the basal and the supplemented diet (200 mg kg(-1) α-tocopheryl acetate) in unprocessed thighs was 8.69 and 16.87, μg g(-1) dry matter, not including ash, respectively (p-value=0.015), while the concentration was 6.65 and 14.28 μg g(-1), respectively, in the final products (p-value=0.011). Hams from pigs fed the basal diet oxidized more during storage (p-value=0.015) as measured by formation in thiobarbituric acid reactive substances and had a higher rate of weight loss (p-value=0.0001). The total loss in red color after 4 days of storage was similar in all treatments. However, the rate of discoloration was more pronounced during the first 2 days of storage in hams from pigs fed the basal diet (p-value=0.016). This result indicates that high dietary level of α-tocopheryl acetate to pigs increases the oxidative stability in dry cured hams manufactured on the basis of such pigs.     

α-Tocopherol, β-Carotene and Ascorbic Acid as Antioxidants in Stored Poultry Muscle

Broilers were fed α-tocopherol or β-carotene for 3 wk or L-ascorbic acid for 24 hr prior to slaughter. α-Tocopherol maintained the redness of unheated meat stored for 8 wk (—20°C). Values for thiobarbituric acid reactive substances in ground, stored meat showed that L-ascorbic acid produced results similar to the control while a-tocopherol produced results lower than the control. Panelists rated meat with added α-tocopherol as different from the control for smell and flavor. β-Carotene was a pro-oxidant compared to the control and other additives. Meat from broilers fed β-carotene had lower α-tocopherol content than the control. Vitamin A in livers of birds fed β-carotene was 64% higher than that of the control.     

Thiamin, Riboflavin and α-Tocopherol Retention in Processed and Stored Irradiated Pork

Combination treatments for preservation of irradiated pork were investigated with respect to vitamin loss. Ground pork was prepared under nitrogen and packaged in anaerobic foil. The samples were enzyme denatured by heating before and after irradiation, then cooked and stored. Irradiation resulted in thiamin loss, but neither riboflavin nor α-tocopherol was affected. Neither thiamin nor riboflavin was affected by heat denaturation, cooking or storage, but heating and cooking increased the measured α-tocopherol. The lack of loss of the vitamins was attributed to the exclusion of oxygen.     

The relationship between the levels of α-tocopherol and carotenoids in the maternal feed,yolk and neonatal tissues: comparison between the chicken,turkey, duck and goose

The relationship between the levels of the lipid-soluble antioxidants, α-tocopherol and carotenoids, in the parental diet, the yolk and the neonatal tissues was investigated for four avian species of commercial importance. The chicken displayed a much greater efficiency in incorporating α-tocopherol from the parental diet into the yolk in comparison with the turkey, duck and goose. Thus, in spite of similar concentrations in the respective diets, the resultant concentration of α-tocopherol in the yolk of the chicken egg was four to five times greater than observed for the other three species. A similar but less dramatic picture was observed for carotenoids: identical dietary provision of carotenoids in the maternal feeds resulted in the chicken eggs displaying between 1·4 and 1·9 times the concentration in the yolk than was observed for the other three species. These differences between the species regarding the levels of α-tocopherol and carotenoids in the yolk were closely reflected in the subsequent concentrations of these components in the livers of the hatchlings. Thus, the concentrations of α-tocopherol and carotenoids in the liver of the day-old chicken were respectively about three and two times greater than in the livers of the other three species. Although the water-soluble antioxidant, ascorbic acid, is synthesised by the embryo as opposed to provision via the maternal diet and the yolk, the concentration of this component in the brain of the day-old chicken was approximately 50% greater than in the brains of the other three species. Thus, it is possible that the antioxidant capacity of the developing turkey, duck and goose may be compromised under conditions of commercial production. All four species displayed a rapid depletion of α-tocopherol and carotenoids from the livers during the first 9 days after hatching. © 1998 SCI.     

Effects of Dietary Oils and α-Tocopherol Supplementation on Lipid Composition and Stability of Broiler Meat

Broilers were fed diets containing oils of varying degrees of unsaturation, namely coconut oil, olive oil, linseed oil and partially hydrogenated soybean oil (HSBO), with and without α-tocopherol supplementation. The different oils significantly (P<0.01) affected the fatty acid composition of the neutral lipids and, to a lesser extent, the fatty acid composition of the phopholipids. Fatty acid composition, in turn, influenced the oxidative stability of the meat during refrigerated and frozen storage. Meat from broilers fed olive oil or coconut oil was consistently more stable than meat from the linseed oil group. Dietary supplementation with α-tocopherol significantly (P<0.01) improved the oxidative stability of the dark and white broiler meat during refrigerated and frozen storage compared to meat from the broilers fed HSBO.     

Effects of lipophilic and hydrophilic antioxidants in oil-in-water emulsions under chlorophyll photosensitization

Antioxidative or prooxidative properties of α-tocopherol, Trolox, ascorbic acid, and ascorbyl-palmitate at the concentration of 0.1 and 1.0 mM were determined in oil-in-water (O/W) emulsions under chlorophyll photosensitization. Headspace oxygen depletion, lipid hydroperoxides, and headspace volatile analyses were conducted to determine the oxidative stability of O/W emulsions. For 32 h visible light irradiation, depleted headspace oxygen content in O/W emulsions were in the order of samples containing Trolox, ascorbic acid, ascorbyl palmitate, α-tocopherol, without antioxidants under light, and samples in the dark, which implies that all the added compounds acted prooxidant. These prooxidative properties of added compounds can be observed in the results of lipid hydroperoxides and headspace volatiles. Samples containing ascorbic acid and ascorbyl palmitate retained higher chlorophyll content than those containing Trolox up to 16 h. Increases of concentration of Trolox, ascorbic acid, and ascorbyl palmitate from 0.1 to 1.0 mM increased the lipid oxidation products whereas α-tocopherol decreased the degree of lipid oxidation implying α-tocopherol may not share the same prooxidant mechanisms compared to other compounds in chlorophyll sensitized O/W emulsions.