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).     

Effect of α-Tocopherol, β-Carotene, and Sodium Tripolyphosphate on Lipid Oxidation of Refrigerated, Cooked Ground Turkey and Ground Pork

ABSTRACT α-Tocopherol and β-carotene at 0.03% levels and sodium tripolyphosphate (STP) at 0.2% and 0.3% levels, alone and in combination, were added to ground turkey and ground pork. Hexanal was measured after cooking and storage at 4 °C for 2, 4, or 6 d. α-Tocopherol alone significantly reduced hexanal of stored, cooked, turkey but had no effect in pork. STP was more effective than α-tocopherol and a combination of α-tocopherol with STP resulted in enhanced antioxidant activity. Hexanal of pork with 0.03%α-tocopherol plus 0.3% STP did not increase significantly during storage, and that of turkey increased only slightly. β-Carotene and salt (1% NaCl) had no effect on hexanal.     

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.     

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.     

Simultaneous HPLC quantification of total cholesterol,tocopherols and β-carotene in Barrosã-PDO veal

A simple, rapid and sensitive procedure for the simultaneous determination of total cholesterol, tocopherols and β-carotene in meat is described. The method involves a direct saponification of the meat, a single n-hexane extraction and the analysis of the extracted compounds by normal-phase HPLC, using fluorescence (tocopherols) and UV–Vis photodiode array (cholesterol and β-carotene) detections in tandem. Rates of recovery of spiked meat samples were 93% for cholesterol, 83–86% for (α-, β- and -γ) tocopherols and 89% for β-carotene. Repeatabilities were high (CV < 6%) for all determined compounds, except for δ-tocopherol. This tocopherol, which is not usually present in meat, showed a much lower recovery percentage (73%) and repeatability (12.8%). This methodology was applied for the quantification of total cholesterol, tocopherols and β-carotene in three muscles (longissimus thoracis, longissimus lumborum and semitendinosus) of the Portuguese traditional Barrosã-PDO veal, obtained from autochthonous calves fed extensively during summer (with the least abundant green pastures) and slaughtered in early autumn (October). Barrosã-PDO veal showed median contents of total cholesterol (0.50–0.56 mg/g) and, depending on the analysed muscle, moderate to high contents of α-tocopherol (3.3–3.9 μg/g) and β-carotene (0.07–0.09 μg/g), suggesting an high sensorial and hygienic quality.     

Oxidative stability and its relationship with natural antioxidants during refrigerated retail display of beef produced in Argentina

The objective of this study was to determine if pasture or grain diets affect oxidative/antioxidative status and the color stability of beef during retail display. Ten crossbreed steers were fed on pasture. Five of them were randomly assigned to remain on this diet, and the other five were finished on feedlot system (grain diet) during 110days until slaughter. Slices of Psoas major steaks were randomly distributed among retail display times (1, 3, 5, 7 and 9days). Lipid and protein oxidation were higher in Psoas major steaks from grain diet than in pasture diet (P<0.05). After 3days of display, lipid oxidation increased in meat from grain diet, whereas in meat from pasture diet the first evidence was after 7days (P<0.05). Protein oxidation was higher in meat from grain diet than in meat from pasture diet at day 9 of display (1.15±0.92 vs. 1.91±0.70μg/g, respectively; P<0.05). Antioxidant vitamins, α-tocopherol and β-carotene were higher at time=0 in pasture Psoas major steaks (P<0.05) and were differentially reduced throughout storage. While α-tocopherol decreased 41% and 57% for pasture and grain beef respectively (P<0.05), β-carotene levels remained practically unaffected in grain beef. After 7days of display "a" value was higher for Psoas major steaks from pasture diet (P<0.05). Besides, "L" parameter showed higher values for samples from grain diets but it was no affected by display time. No differences were observed between both treatments for "b" value, but a significant decrease (P<0.05) was observed along storage. Superoxide dismutase and catalase activity was stable throughout storage, while glutathione peroxidase activity decreased significantly (P<0.05). The results in this study demonstrated that the higher initial level and synergistic action (under light and air) of α-tocopherol and β-carotene found in pasture-finished animals improved the oxidative and color stability of beef, as showed by a better retention of redness at the end of retail display.     

Serum retinol, β-carotene,and α-tocopherol as biomarkers for disease risk and milk production in periparturient dairy cows

The effectiveness of using serum vitamin concentrations as biomarkers to predict diseases in dairy cows during the periparturient period is not well known. The objective of this study was to evaluate the association between serum β-carotene, retinol, and α-tocopherol concentrations and periparturient cow diseases in commercial dairies. We measured serum concentrations of these vitamin-active compounds at dry-off and during close-up (approximately 3 wk before calving) and early lactation (approximately 7 d post-calving), and we examined their association with clinical diseases in the first 30 d in milk. Diseases were diagnosed by trained personnel and recorded using database software. Blood samples were taken from 353 cows from 5 different farms over a 3-yr period. Blood samples were analyzed for β-carotene, retinol, α-tocopherol, and cholesterol. We built separate mixed logistic regression models for each disease outcome: hyperketonuria, lameness, mastitis, uterine diseases (retained placenta or metritis), and an aggregate outcome. For the aggregate outcome, a cow was considered positive if she had one or more of the following: hyperketonuria, lameness, mastitis, uterine disease, pneumonia, milk fever, or displaced abomasum. Concentrations of all 3 fat-soluble vitamins decreased significantly in early lactation relative to the 2 prepartum sampling times. Serum retinol concentrations at close-up and early lactation were negatively associated with odds of developing postpartum hyperketonuria. At early lactation, cows with uterine disease had lower serum retinol concentrations than cows without uterine disease. Similarly, lower serum retinol concentrations were associated with greater odds of having any one disease in the aggregate outcome. First-test 305-d mature-equivalent milk yield was positively correlated with increased serum α-tocopherol and negatively correlated with β-carotene concentrations. This study demonstrates the potential for serum β-carotene, retinol, and α-tocopherol to serve as biomarkers for disease risk.     

α-Tocopherol Content and Oxidative Stability of Egg Yolk as Related to Dietary α-Tocopherol

Hens fed diets with 0.0, 7.5, 15.0, 30.0, 60.0 and 120.0 mg supplemental α-tocopherol/kg feed produced egg yolks with 25,30,35,45,50 and 75 μg/g yolk, respectively. The correlation coefficient between dietary α-tocopherol (mg/kg diet) and egg yolk α-tocopherol (μg/g egg yolk) after 28 days feeding was 0.99. The supplemented dietary α-tocopherol had an effect on the α-tocopherol in egg yolk (p<0.05). The oxidative stability of yolk was determined by measuring the oxygen and volatile compounds in the headspace of bottled yolk. α-Tocopherol had an effect on the stability of yolk as an antioxidant at 25, 45 and 50 μg/g yolk and a prooxidant at 75 μg/g or above (p<0.05). The addition of 60.0 mg α-tocopherol/kg diet resulted in the best egg yolk stability. The correlation coefficient between headspace oxygen disappearance and volatile compound formation in the headspace of bottled egg yolk was 0.84.     

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.     

Effects of prepartum supplementation of β-carotene on colostrum and calves

Little is known about transfer of dietary β-carotene into colostrum, its absorption by the calf, and its effects on retinol and α-tocopherol in the calf when the dam's dietary vitamin A is adequate. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period on the colostrum and calf. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were blocked by calving data, parity, and previous production, and then randomly assigned to either control or β-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, DSM Nutritional Products, 8 g/d; provided 800 mg β-carotene) or carrier from 21 d before expected calving until calving. Colostrum was collected within 2 h of parturition. Calf blood samples were obtained within 2 h of birth before receiving the dam's colostrum, at 24 h after birth, and at 7 d and 60 d of age. Blood serum was analyzed for β-carotene, retinol, α-tocopherol, and other metabolites and enzymes. Colostrum was analyzed for β-carotene, retinol, α-tocopherol, colorimetry profile, and milk components. Data were analyzed using mixed-effects models in SAS (SAS Institute Inc.). Calf serum β-carotene data were analyzed using the FREQ procedure. Colostrum β-carotene was higher for BC cows. Colostrum from BC cows had increased a* [measures red (positive) to green (negative)] and b* [measures yellow (positive) to blue (negative)] colorimeter values, indicating that β-carotene altered colostrum color toward red and yellow. Supplementation did not affect colostral or calf IgG concentrations. Colostrum color indices were correlated with IgG concentrations as well as concentrations of β-carotene, retinol, and α-tocopherol. Before receiving colostrum, the concentration of β-carotene in calf serum was below the detectable threshold of 0.05 μg/mL. At 24 h of age, the number of calves with detectable β-carotene concentrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from cows in the control group (6.1%). No differences in concentrations of retinol or α-tocopherol were observed in calf serum. Supplementation of β-carotene to cows decreased activities of gamma-glutamyl transpeptidase and glutamate dehydrogenase in calf serum. In pregnant cows already receiving adequate vitamin A, supplementation of β-carotene increased concentration of β-carotene in colostrum, altered colostrum color, and increased serum β-carotene in calves at birth.     

Oxidative stability enhancement of broiler bird meats with α-lipoic acid and α-tocopherol acetate supplemented feed

Depression of meat quality is known to be caused by lipid peroxidation occurring in meat. Supplementation of antioxidants in feed decreases lipid peroxidation and improves the oxidative stability of meat after slaughtering. The present study demonstrated that meat obtained from broiler birds fed feed supplemented with α-tocopherol acetate (200 mg/kg feed) along with α-lipoic acid (25, 75, or 150 mg/kg feed) exhibited increased oxidative stability and reduced fat content. The total phenolic content and α-lipoic acid content increased in the meat as the concentration of α-lipoic acid supplementation increased. The protein content in the meat was not changed by the supplementation of α-lipoic acid and α-tocopherol acetate. The results of DPPH and TBA assays demonstrated that feed supplemented with α-lipoic acid and α-tocopherol acetate also enhanced the antioxidant activity of broiler meat. On the other hand, the meat from broiler birds fed feed supplemented with oxidised oil (4% in feed) reduced its oxidative stability.     

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.     

Effects of prepartum supplementation of β-carotene in Holstein cows

Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health.     

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.     

Effects of α-tocopherol, β-carotene and ascorbyl palmitate on oxidative stability of butter oil triacylglycerols

Butter oil triacylglycerols (BO-TAGs), free of antioxidants, including β-carotene, were obtained via sequential treatments with activated carbon (AC) adsorption and alumina column chromatography. α-Tocopherol, β-carotene and ascorbyl palmitate (AP) were added to BO-TAGs, individually, or in different combinations. An accelerated oven-oxidation test was carried out at 60 °C to determine the most effective dosages of the antioxidants. Among the antioxidants evaluated, α-tocopherol was found to be the most effective, at the concentration of 50 μg/g. To determine the possible synergism between the antioxidants, binary or ternary combinations of α-tocopherol, β-carotene and AP were added to BO-TAGs at concentrations of 50, 5, and 50 μg/g, respectively. Ternary combinations of these antioxidants were significantly better in retarding oxidation than were binary blends of α-tocopherol with β-carotene or AP. However, a prooxidant effect was observed, especially when β-carotene and AP were used individually or in binary combination.     

ANTIOXIDANT CONTENT AND MARKET QUALITY OF JALAPENO PEPPER RINGS AS AFFECTED BY MINIMAL PROCESSING AND MODIFIED ATMOSPHERE PACKAGING

Retention of β-carotene in jalapeno pepper rings after 12 days' storage at 4.4C, and an additional 3 days at 13C was 87% in modified atmosphere packages (MAP, 5% O₂, 4% CO₂) and 68% in air. Retention of α-carotene was 92% in MAP and 52 % in air after 15 days, while ascorbic acid retention after 15 days was 83% in MAP and 56% in air. MAP retarded the conversion of L-ascorbic acid to dehydroascorbic that occurred in air stored peppers. Most antioxidant losses occurred within 3 days after minimal processing. MAP treatment resulted in greater preservation of quality attributes (texture, color and moisture content) and antioxidants than air stored peppers.     

Effect of Sicilian pasture feeding management on content of α-tocopherol and β-carotene in cow milk

This study was performed to evaluate α-tocopherol and β-carotene contents of pasture milk under ordinary Sicilian farming conditions. Fourteen dairy farms were allocated into 2 balanced groups on the basis of cultivated (CULT) or spontaneous (SPO) pasture type feeding. Bulk milk per farm was collected 4 times from February through April at 3-wk intervals. Pasture botanical and diet composition, diet nutritional quality, milk yield and composition were estimated each time. Pasture intake levels were calculated based on feed analyses, hay and concentrate amounts fed, and milk yield and chemical composition. According to pasture intake, the farms were split into low pasture intake (LPI; <29.5% of dry matter) and high pasture intake (HPI; >29.5% of dry matter) groups. Milk samples per farm were analyzed for α-tocopherol and β-carotene contents by HPLC. The SPO group had higher levels of α-tocopherol and β-carotene in milk (0.7 and 0.3 mg/L, respectively) and milk fat (19.0 and 7.5 mg/kg fat, respectively) compared with the CULT group in milk (0.5 and 0.2 mg/L, respectively) and milk fat (14.6 and 4.9 mg/kg, respectively). High pasture intake compared with LPI increased α-tocopherol in milk fat (18.0 and 16.0 mg/kg of fat, respectively). However, only in the SPO (not in CULT), HPI compared with LPI increased milk α-tocopherol (0.8 vs. 0.6 mg/L, respectively), milk β-carotene (0.3 vs. 0.2 mg/L, respectively), and milk fat β-carotene (8.4 vs. 6.6 mg/kg, respectively). Results may be related to the different botanical composition of the respective pasture types and pasture intake. Spontaneous pasture compared with CULT contained a higher mass proportion of Asteraceae, Fabaceae, Cruciferae, Euphorbiaceae, and Malvaceae plants. Milk and milk fat α-tocopherol levels were higher on test-days (TD)-1, TD-2, and TD-4 compared with TD-3. For HPI farms, milk fat β-carotene content was higher on the first 2 TD compared with the last 2 TD. These differences could be related to plant biological stage. On Sicilian dairy farms, the highest milk α-tocopherol and β-carotene contents may be obtained feeding high levels of SPO pasture in the spring.     

Effect of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken

The effects of dietary α-tocopherol supplementation and gamma-irradiation on α-tocopherol retention and lipid oxidation in cooked minced chicken during refrigerated storage were studied. Minced breast and thigh meat from broilers fed diets supplemented with 100, 200 or 400 mg α-tocopheryl acetate/kg feed was irradiated at 2.5 or 4.0kGy. Cooked irradiated and unirradiated meat was stored at 4 °C for 5 days. α-Tocopherol concentrations increased with increasing dietary supplementation. Concentrations decreased during storage, but retention was not affected by irradiation. Lipid stability was determined by measuring the formation of thiobarbituric acid-reacting substances (TBARS) and cholesterol oxidation products (COPs) during storage. TBARS and COPs increased during storage and were reduced by increasing levels of dietary α-tocopheryl acetate supplementation. Irradiation accelerated TBARS formation during storage, but this was prevented by supplementation with 200 mg α-tocopheryl acetate/kg feed. Irradiation tended to increase COPs during storage, although no consistent effects were observed. In general supplementation with over 400 mg α-tocopheryl acetate/kg feed may be required to control cholesterol oxidation in minced chicken. The results suggest that, overall, irradiation had little effect on lipid stability in α-tocopherol-supplemented meat following cooking and storage.     

Effect of dietary α-linolenic acid and vitamin E on the fatty acid composition, storage stability and sensory traits of rabbit meat

The synergistic effect of dietary linolenic acid and vitamin E on the oxidative stability and nutritional and eating characteristics of fresh and stored rabbit meat was studied. One-hundred hybrid male rabbits were divided into two homogenous groups and fed ad libitum two diets differing in the amount of sunflower and flaxseed and in the level of α-tocopherol, as follows: control diet: 0.08 kg kg(-1) sunflower, 50 mg kg(-1) α-tocopheryl-acetate and LNA-VE diet: 0.08 kg kg(-1) flaxseed, 200 mg kg(-1) α-tocopheryl-acetate. At 85 days, 20 rabbits per group were slaughtered and the thiobarbituric-acid reactive substances (TBA-RS), chemical composition, fatty acid profile and sensory quality were assessed on the longissimus dorsi muscles (fresh and stored for 8 days at 4?°C). The proximate composition of the fresh muscle was not significantly affected by the dietary treatment. Rabbits fed the LNA-VE diet showed a good capability to elongate and desaturate linolenic acid and this diet enriched the n-3 PUFA content of the meat without affecting its peroxidative stability. The sensory quality of the fresh and stored muscle was slightly affected by the dietary treatment, even though final tenderness (fresh meat) and overall acceptability (stored meat) of the LNA-VE rabbits showed significantly higher scores.     

Influence of pasture or grain-based diets supplemented with vitamin E on antioxidant/oxidative balance of Argentine beef

Argentine meat has been traditionally produced on pasture. However, to comply with some market requirements, grain finishing is becoming more common among producers. The main goal of the present work was to study lipid oxidation in fresh meat from animals fed different diets in relationship with their antioxidant vitamin status. Attributes were evaluated in beef from pasture or grain-fed animals with (PE and GE) or without supplementation (P and G) with vitamin E (500 UI/head/day). Fresh meat produced on grain (G and GE) had higher fat (4.0±1.6 and 4.7±1.4 g/100 g) and cholesterol content (51.0±3.0 and 52.0±4.0 mg/100 g) than meat from pasture (P and PE) fed animals (2.7±1.2 to 2.9±1.1 g/100 g and 48.0±5.0 to 49.0±4.0 mg/100 g of intramuscular fat and cholesterol respectively). Fatty acid composition was clearly affected by diet. Beef from pasture-fed cattle had higher percentage of linolenic acid, less linoleic acid and, overall, higher percentage of polyunsaturated fatty acids than beef from grain-fed animals (P<0.05). Thiobarbituric acid reactive substances number and volatile levels of hexanal, pentanal, heptanal, octanal and 3-methylbutanal were higher in grain than in pasture samples (P<0.05). P+PE meat had higher content of antioxidant vitamins than G+GE samples (P<0.001). Values ranged from: 15.92±3.48 (G) to 17.39±4.29 (GE) and 25.3±10.0 (P) to 21.98±5.11 (PE) μg/g of ascorbic acid; from 1.05±0.73 (G) to 1.76±0.97 (GE) and 3.08±0.45 to 3.91±0.74 μg/g of α-tocopherol; and from 0.06±0.03 (G) to 0.05±0.01 (GE) and 0.45±0.21 (P) to 0.63±0.27 (PE) μg/g of β-carotene. In addition, principal component analysis clearly separated grain from pasture samples regardless of their supplementation with vitamin E. This level of supplementation did not improve the antioxidant status of fresh meat (P>0.05). We conclude that pasture diet contributes natural antioxidants in sufficient amounts and is an efficient way to prevent lipid oxidation in fresh beef.