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.     

Stability of α-tocopherol, γ-tocopherol and β-carotene during ripening of pasta-filata cheese made from raw and pasteurised milk with different vitamin contents

Ripening stability of α-tocopherol, γ-tocopherol and β-carotene in cheese was evaluated in relation to different milk vitamin content and to the use of either pasteurised or raw milk. Milk from two farms with different management systems was used to obtain different vitamin content. Milk was divided into two parts, of which only one was pasteurised. Four blocks of cheese were made from each batch and ripened for 0, 15, 30, or 60 days at 14–16 °C. There was a notable variation in cheese vitamin levels, with the differences in milk vitamin content due to farm management having the highest impact. Pasteurisation had no effect on cheese vitamin content. Cheese γ-tocopherol and β-carotene content decreased after 30 and 60 days, respectively, whereas α-tocopherol content remained stable. γ-Tocopherol appeared to be the most efficient antioxidant in cheese, followed by β-carotene. Vitamin stability was not influenced by milk vitamin content or pasteurisation.     

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.     

Antioxidant capacities of α-tocopherol,trolox, ascorbic acid,and ascorbyl palmitate in riboflavin photosensitized oil-in-water emulsions

Antioxidant capacities of α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate at 0.01, 0.1, and 1.0 mM in riboflavin photosensitized oil-in-water (O/W) emulsions were determined using headspace oxygen depletion, lipid hydroperoxide, and headspace volatile analyses. After 32 h visible light irradiation, headspace oxygen in O/W emulsions without adding antioxidants, with 1.0 mM α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate decreased to 18.50%, 18.85%, 16.01%, 17.92%, and 19.88%, respectively, whereas those samples in the dark were 20.74%. Trolox and ascorbic acid acted as prooxidants while their lipophilic counterparts, α-tocopherol and ascorbyl palmitate, respectively showed antioxidant properties. Similar antioxidative or prooxidative properties of the tested compounds can be observed in the results of lipid hydroperoxides and headspace volatiles. However, the prooxidant and antioxidant properties of the tested compounds were not clearly shown at 0.01 and 0.1 mM concentration. Both the type and concentration of antioxidants influenced the antioxidant capacities in riboflavin photosensitized O/W emulsions.     

Antioxidant mechanism of grape procyanidins in muscle tissues: Redox interactions with endogenous ascorbic acid and α-tocopherol

The present study investigates the antioxidant mechanism of grape procyanidins and, in particular, their aptitude to establish redox interactions with two important components of the endogenous antioxidant system of muscle tissues, α-tocopherol (α-TOH) and ascorbic acid (AA). To this end, the progress of lipid oxidation was monitored in fish muscle supplemented with grape procyanidins at the concentrations usually employed in antioxidant food applications, and then related to the redox stability of the endogenous α-TOH and AA. In addition to the lipid oxidation protective effect, the incorporation of procyanidins also provided an improvement of the redox stability of the endogenous components in a straight procyanidinic concentration-dependent manner. Results showed the capacity of procyanidins to repair oxidised α-TOH at medium-long term, and to delay the AA depletion. Therefore, such cooperative redox interaction of exogenous procyanidins adequately complements the natural α-TOH regenerative system supplied by AA that is efficient at the early post mortem stages.     

A review of natural antioxidants and their effects on oxidative status, odor and quality of fresh beef produced in Argentina

Meat derived from pasture feeding, is associated with a high level of antioxidants. Antioxidants are incorporated within cell membranes and protect tissues against oxidation from reactive oxygen species. This maintains the overall quality of meat and secondary products. This paper reviews the implications of incorporating natural antioxidants into fresh beef, focusing on the benefits of feeding cattle good quality pasture. Pasture samples typically have higher levels of α-tocopherol, β-carotene, ascorbic acid and glutathione than feedlot samples. These compounds retard lipid and protein oxidation in fresh and stored meat, and preserve the color and odor quality of beef. The significance of antioxidant enzymes is variable, because their behavior depends on individual redox status before slaughter. Understanding total antioxidant activity requires information on antioxidant and pro-oxidant status. With an abundance of pasture, Argentina has a natural advantage in producing meat with a high antioxidant value.     

Effects of chitosan and collagen containing α-tocopherol on the oxidative stability in bulk oil and oil-in-water emulsion

To provide efficient antioxidant capacities, proper carriers are needed to protect antioxidants against oxidative stress. Collagen mesh structure or chitosan gel was loaded with α-tocopherol and their effects were evaluated in bulk corn oil or oil-in-water (O/W) emulsion at 60 °C. Added collagen and chitosan enhanced oxidative stability in corn oil and O/W emulsions at 60 °C compared to corn oils without carriers or with addition of α-tocopherol (p < 0.05). Stability of α-tocopherol in corn oil loaded in collagen or chitosan was significantly enhanced compared to that in oils without carriers (p < 0.05). In O/W emulsions, α-tocopherol loaded collagen showed higher antioxidant properties than α-tocopherol loaded chitosan (p < 0.05). Collagen mesh structure and chitosan gel retarded the rates of lipid oxidation efficiently in both food matrices when α-tocopherol was not loaded. Collagen mesh structure and chitosan gel can be useful carriers for α-tocopherol in bulk oil or O/W emulsion.     

Antioxidant activity of Spirulina platensis extracts by supercritical carbon dioxide extraction

Supercritical CO₂ extraction of antioxidants from Spirulina platensis was optimized using response surface methodology. About 10.26 g/kg of extracts from S. platensis could be obtained under the optimum conditions of 48 °C at 20 MPa over a 4 h period. The antioxidant activity of the extracts prepared under the optimized condition, determined by linoleic acid peroxidation inhibition method, was lower compared with BHT and Trolox, but significantly higher than α-tocopherol in 300 min and became similar to α-tocopherol after that. The components of the extracts were further analyzed, and the results showed that the extracts contained 85.1 g/kg of flavonoids, 77.8 g/kg of β-carotene, 113.2 g/kg of vitamin A and 3.4 g/kg of α-tocopherol, which may contribute greatly to their high antioxidant activity. The main fatty acids in the extracts were palmitic acid (35.32%), linolenic acid (21.66%) and linoleic acid (20.58%).     

Impact of supercritical carbon dioxide turmeric extract on the oxidative stability of perilla oil

The objective of this study was to determine the efficacy of supercritical carbon dioxide turmeric extract (STE) on the oxidative stability of perilla oil (PO), as measured by acid value (AV), peroxide value (PV) and oxidation induction time and compared to control and α-tocopherol containing PO as a positive control. The antioxidant activity was determined by DPPH, ABTS and FRAPS assays and individual bioactive compounds identified by chromatography. STE demonstrated significantly higher antioxidant activity than the α-tocopherol. The major components of the STE were identified as ar-turmerone, turmerone, curlone and bisabolene by GC-MS and curcumin and demethoxycurcumin by UPLC-Q-TOF MS. During thermal treatment at 65 °C for 24 h, the PO containing STE at different concentrations (100, 300, 500 and 1000 μg mL⁻¹) had significantly lower AV and PV, and at least 1.5 times higher induction period than those of the control and α-tocopherol-incorporated PO.     

Stability of α-Tocopherol, Thiamin, Riboflavin and Retinol in Pork Muscle and Liver during Heating as Affected by Dietary Supplementation

The α-tocopherol (Vit E) and ascorbic acid (Vit C) supplementation of pig diets increased (P<0.05) liver α-tocopherol concentrations. After heating, the liver samples of both treated groups and the longissimus dorsi muscle samples of the vitamin C group showed increased riboflavin retention (P<0.05). The supplemented and control groups did not show differences regarding retention of α-tocopherol, retinol and thiamin in heated liver and longissimus dorsi. Dietary vitamin C resulted in higher liver vitamin E and was most effective in protecting riboflavin against loss during heating of liver or longissimus dorsi.     

Stability in the rumen and effect on plasma status of single oral doses of vitamin D and vitamin E in high-yielding dairy cows

The ruminal fate of the fat-soluble vitamins D and E was studied in dairy cows. Ten to 15 kg of ruminal contents was taken from each cow through a ruminal fistula. A sample was taken out (0-h sample) and the rest of the contents were mixed with 4,360 mg of all-rac-α-tocopheryl acetate (vitamin E; study 1) or 4,360 mg of all-rac-α-tocopheryl acetate, 250 mg of ergocalciferol (vitamin D₂), and 250 mg of cholecalciferol (vitamin D₃; study 2). After mixing, the ruminal contents were returned to the respective cows. Blood was collected 0, 6, 24, and 30 h after introducing the vitamins into the rumen. Samples of ruminal contents were collected at 0, 1, 2, 4, 6, 24, and 30 h (in vivo). From the 1-h sample, 6 subsamples from each cow were incubated at 37°C and taken out at 2, 4, 6, 12, 24, and 30 h (in vitro). In vivo concentrations of added α-tocopherol, ergocalciferol, and cholecalciferol in the rumen first increased and subsequently declined due to dilution effects of eating and passage out of the rumen. The level of the free-alcohol form of α-tocopherol from the natural content in feed was constant throughout the in vivo study, in contrast to the content of total α-tocopherol, which indicated that no hydrolysis of the acetate form into alcohol form happened in the rumen. In vitro, all added vitamins were found at constant levels; hence, none of the added vitamins were degraded in ruminal contents. The concentration of α-tocopherol in plasma increased at a rate per milligram of ruminally introduced α-tocopherol below the rate of the increase in plasma ergocalciferol or cholecalciferol metabolites per milligram of introduced ergocalciferol or cholecalciferol, respectively, over 24 h. In conclusion, ergocalciferol, cholecalciferol, and α-tocopheryl acetate proved to be stable in the rumen and in ruminal contents from high-yielding dairy cows. Changes in plasma concentrations of the vitamins relative to the amount of vitamin introduced to the rumen indicated a lower effect on plasma status of ergocalciferol than of cholecalciferol, and an even lower effect of α-tocopherol. The limited plasma response after a single dose of α-tocopheryl acetate led to the conclusion that oral single dose therapy with all-rac-α-tocopheryl acetate is of limited physiological value.     

Oxidative Stability of Soybean Triacylglycerol Using Carotenoids and Y-Tocopherol

The effect of lycopene, β-carotene, and γ-tocopherol on the oxidative stability of soybean triacylglycerol was evaluated under Schaal oven conditions at 60°C. Peroxide value, conjugated diene, hydroperoxides, and thiobarbituric acid reactive substances were used as indicators for primary and secondary lipid oxidation products, whereas Rancimat method was used to study the oil stability. Results indicated that lycopene and β-carotene acted as pro-oxidants, whereas γ-tocopherol acted as antioxidant in triacylglycerol. Pro-oxidative activity of lycopene was higher than β-carotene at 100 and 200 ppm levels under Schaal oven thermal conditions. The combination of lycopene and γ-tocopherol (1:2) acted as antioxidant with better efficiency than γ-tocopherol alone in inhibiting the hydroperoxide formation in triacylglycerols.     

Palm-tocotrienol rich fraction (TRF) is a more effective inhibitor of LDL oxidation and endothelial cell lipid peroxidation than α-tocopherol in vitro

Comparative protective effects of palm tocotrienol rich fractions (TRF) and α-tocopherol on the copper-induced oxidation of plasma low density lipoprotein (LDL) and indices of lipid peroxidation in human umbilical vein endothelial cells (HUVEC) were investigated. LDL (100 μg protein/ml) was incubated at 37 °C with 1 μM CuSO₄ with or without the presence of 50 μM (TRF) or 50 μM α-tocopherol. Aliquots were collected at 0,1,2,3,6,9,12 and 24 h and thiobarbituric acid reactive substances (TBARS) determined. In the absence of antioxidant, TBARS increased significantly in LDL reaching a maximum after 6 h. α-Tocopherol and TRF delayed TBARs formation by 6 h with a maximum effect after 12 h. The rate of TBARs formation with TRF was significantly slower than with α-tocopherol, indicating a higher antioxidant efficacy for TRF. Low density lipoprotein isolated from volunteers consuming low or high polyunsaturated fatty acid (PUFA) diets were similarly incubated with 1 μM CuSO₄ with or without 50 μM TRF or 50 μM α-tocopherol. LDL oxidation was not significantly different between low and high PUFA groups. However, LDL treated with TRF was better protected against copper-induced oxidation than that treated with α-tocopherol. In HUVEC pre-incubated with 100 μM arachidonic acid, 25 μM TRF treatment decreased TBARS by ∼73% compared to ∼50% with 25 μM of α-tocopherol. Higher concentrations of TRF did not further decrease TBARS formation in the medium. However, treatment with higher concentrations of α-tocopherol again increased TBARS formation. Formation of conjugated diene in HUVEC subjected to arachidonic acid (ARA)-induced oxidative stress was decreased equally with either 10 μM TRF or 25 μM α-tocopherol. Results suggest that TRF is a more potent antioxidant than α-tocopherol, at least in vitro.     

Effect of vitamin E supplementation on α-tocopherol and β-carotene concentrations in tissues from pasture- and grain-fed cattle

The effects of dietary vitamin E supplementation of grain-fed cattle on lipid oxidation and meat colour have been extensively investigated, but little attention has been given to pasture-fed cattle where meat is likely to contain naturally high amounts of α-tocopherol and carotenoids. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation on tissue levels of anti-oxidants and compared the findings with those obtained for grain-fed cattle with and without supplementation. Sorghum was the major component of the grained-based ration. α-Tocopherol concentrations in plasma, muscle and fat tissues of pasture-fed cattle were not affected by vitamin E supplementation (2500 IU/head/day for 132 days prior to slaughter) while those of grain-fed cattle increased significantly. The α-tocopherol concentrations in the supplemented grain-fed cattle were similar in muscle and liver to pasture-fed animals but were lower in their fat (P<0.05). The major carotenoid present in all tissues studied from pasture-fed was β-carotene and its contents in plasma, liver, fat and muscles were decreased (P<0.05) by supplementation with vitamin E. Carotenoids were essentially absent in grain-fed cattle except for small amounts in liver. The implication of this study for the meat industry is that cattle grazed on good pasture can achieve concentrations of α-tocopherol in muscles and other tissues at least as high as those obtained by supra-nutritional supplementation of grain-fed cattle with vitamin E. However, α-tocopherol supplementation of pasture-fed cattle reduced tissue concentrations of β-carotene, which would reduce carcase fat yellowness and make pasture-fed cattle more acceptable to some Asian markets.     

Antioxidant activity of tomato lipophilic extracts and interactions between carotenoids and α-tocopherol in synthetic mixtures

In the present study we assayed the antioxidant activity of lipophilic extracts obtained from different tomato varieties. The results showed that cherry tomatoes, characterized by a high carotenoid content, had the highest antioxidant activity. A quantitative analysis of lycopene, β-carotene, lutein and α-tocopherol was also performed and the correlation between the antioxidant content and the antioxidant activity was estimated. The highest correlation coefficient was found for lycopene (R² = 0.9236, P ≤ 0.001). The analysis of two-component mixtures containing α-tocopherol and carotenoids showed that significant synergism occurred for all the combinations which contained α-tocopherol and β-carotene mixed together. The highest synergistic effects were detected for α-tocopherol-lycopene mixtures, which were the most efficient combinations tested in the present study. The analysis of the carotenoid combinations indicated that synergism occurred for lycopene-β-carotene, lycopene-lutein and lutein-β-carotene mixtures. The analysis of four-component mixtures did not show statistically significant synergistic effects.     

Effects of supranutritional dietary vitamin E levels on subcellular deposition of α-tocopherol in the muscle and on pork quality

The influence of three levels of vitamin E in the diet of pigs on the subcellular deposition of α-tocopherol in the muscle and on selected quality characteristics of pork meat (oxidative stability of lipids, colour, drip loss, microbial growth) was studied. The content of α-tocopherol in adipose tissue and L. dorsi muscle as well as in mitochondrial and microsomal fractions of the muscle significantly increased (P < 0.05) with increasing levels of dietary vitamin E. The differences in the concentrations of α-tocopherol in the subcellular fractions were evident in the enhanced stability of the membranes when exposed to metmyoglobin/hydrogen peroxide. The beneficial effect of dietary vitamin E on the oxidative stability of pork lipids during the storage of pork chops and ground pork was also demonstrated. Even though lipid oxidation increased in all cases during storage, the pork products from the pigs receiving the highest level of vitamin E (200 IU kg^?1 feed) exhibited the smallest increase in thiobarbituric acid reactive substances. In addition, increased colour stability and decreased drip loss were observed on keeping pork chops, which had been previously frozen for three months, at 4°C under fluoresent light for 10 days. The possible effect of α-tocopherol on membrane fluidity in this context is discussed.     

Evaluation of synergistic effect of <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> and citric acid on oxidative stability of virgin olive oil

Green microalga Chlorella (Chlorella vulgaris) powder was employed as a natural antioxidant in virgin olive oil and its antioxidant activity was compared with those of β-carotene and α-tocopherol during 16 days of accelerated storage. Furthermore, the synergistic effects of Chlorella and citric acid were investigated. The primary, secondary, and total oxidation products of Chlorella samples (with and without citric acid) were lower than those of the control samples. Induction period of Chlorella samples were significantly higher than those of the control, β-carotene, and α-tocopherol samples. Furthermore, carotenoid and chlorophyll contents of Chlorella samples were significantly higher than those of the control samples. These pigments can delay the oxidation process. Using Chlorella and citric acid in combination with each other showed no synergistic effect against the oxidation of virgin olive oil. In conclusion, Chlorella can be affirmed as a natural antioxidant, which extends the shelf life of virgin olive oil.     

The antioxidant and phylloquinone content of wildly grown greens in Crete

The traditional Mediterranean diet of Crete is renowned for its very high consumption of olive oil, vegetables, legumes, fruit, fish, whole-wheat cereals and a moderate consumption of dairy products and meat. Wild greens play an important role in the traditional diet and are eaten either fresh in salads, boiled or cooked in pies, thus increasing the daily vitamin and antioxidant intake of the population that adheres to the traditional diet. Six cultivated and 48 wildly grown greens were collected and analyzed for their carotenoid, l-ascorbic acid, phylloquinone, γ-tocopherol, α-tocopherol and total polyphenol content. In most cases, the wild greens had higher micronutrient contents than those cultivated. Certain wild greens, such as Rumex obtusifolius, Prasium majus and Lathyrus ochrus had higher concentrations of vitamin K₁, vitamin C, lutein, β-carotene, γ-tocopherol and total polyphenol content than those cultivated; proving the significance of these wildly grown greens for the well being of the Cretan population.     

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.     

Effect of pasteurisation on ascorbic acid,dehydroascorbic acid,tocopherols and fatty acids in pooled mature human milk

Ascorbic and dehydroascorbic acids (vitamin C), tocopherols (vitamin E) and unsaturated fatty acids are heat-sensitive and therefore, their concentrations in human milk could be affected by pasteurisation. Here we determined the concentrations of ascorbic acid plus dehydroascorbic acid, ascorbic acid alone, and α- and γ-tocopherols, and the percentages of fatty acids in samples of human milk after pasteurisation by a slow (62.5 °C, 30 min) or fast heating (100 °C, 5 min) procedure. Both methods led to a significant decrease in the concentrations of ascorbic acid plus dehydroascorbic acid (12% and 29%), ascorbic acid (26% and 41%), α-tocopherol (17% and 34%) and γ-tocopherol (13% and 32%), respectively. However, milk fatty acids, including the polyunsaturated long-chain fatty acids, were unaffected by the two methods. On the basis of these observations, we recommend that human milk be treated using a slow pasteurisation. In addition, we propose ascorbic acid as a marker of the degree of heat treatment.