Supplementation of broiler diets with all-rac-alpha- or a mixture of natural source RRR-alpha-,gamma-,delta-tocopheryl acetate. 2. Effect on the oxidative stability of raw and precooked broiler meat products

A role for Sel-Plex™, a source of organic selenium in selenised yeast cell wall protein, as a factor that influences meat stability

Selenium is an important mineral required in the antioxidant system in animals, which is involved with oxidative stability in tissues, particularly membranes, and is involved in various aspects of meat quality and stability on the shelf, due to its protective properties on lipids, preventing rancidity. Se can be supplied in an inorganic or chemically organic form, and it is well known that the latter has beneficial properties and improved functionality in physiological systems compared to the former. Research has shown that organic Se is associated with increased tenderness and the prevention of certain problems in pale exudative meat, discolouration and off-flavours and odours in meat, although this depends on other components of the antioxidant system, such as vitamin E, being present as well. The change in prominence of glutathione peroxidase forms in their interaction with vitamin E in cell membranes is also noted. The following review (the third in a series) details the research that has been conducted into the role of Se in meat stability and related factors, with specific focus on organic forms of Se, namely the commercial product Sel-Plex™ (Alltech Inc, Nicholasville, KY, USA), which is derived from yeast and in which selenium replaces sulphur in methionine forming selenomethionine in yeast protein.

Effect of dietary turmeric on antioxidant properties of thigh meat in broiler chickens after slaughter

Two hundred and fifty-day-old male broiler chicks (Ross 308) were used to investigate the dietary supplementation effects of different levels of 0.0 turmeric rhizome powder (TRP) (free TRP, F.TRP), 0.25 (low TRP, L.TRP), 0.5 (medium TRP, M.TRP) and 0.75% TRP (high TRP, H.TRP) or 50 mg/kg vitamin E (VE) on antioxidant properties of thigh meat in broiler chickens after slaughter. No effect of treatment was observed for the activities of glutathione peroxidase (GPX) and superoxide dismutase (SOD) and total antioxidant status (TAS) in thigh meat (P > 0.05) but all were reduced over time (P < 0.0001). A significant treatment*time interaction was observed for thigh meat GPX activity (P = 0.02). Significant effects of treatment and time were observed for malondialdehyde (MDA) content (P < 0.05). There was no significant difference between the treatments for thigh meat MDA content at slaughter (P > 0.05). Three days after refrigerator storage, MDA content in thigh meat of M.TRP birds was lower than that of F.TRP birds (P < 0.05). Both the M.TRP and VE birds showed a lower MDA content in thigh meat as compared with F.TRP birds 7 days after storage (P < 0.05). In conclusion, dietary consumption of 5 mg/kg TRP can increases the thigh meat shelf-life storage and quality in broiler chickens after slaughter.

Dietary strategies to improve nutritional value, oxidative stability, and sensory properties of poultry products

Consumers demand both safer and more nutritious food products exempt of non-natural origin preservatives or other food additives. In this frame, products with lower fat content and/or a higher ratio in unsaturated fatty acids, especially n-3 fatty acids, are desired because these lipids can help prevent the development of cardiovascular and inflammatory pathologies. The intake of meat products is of interest because they are an excellent source of vitamins and minerals. In addition, the shelf-life of meat products can be extended by the presence of natural antioxidants coming from different sources such as plant extracts. Therefore, different strategies have been studied to improve the nutritional value, oxidative stability, and sensory characteristics of meat products and eggs through different mineral and natural dietary supplements. In comparison to other strategies, dietary supplements present the advantage that first the living animals may efficiently distribute the compounds throughout the tissues and second, the dietary supplementation is safer because the resulting enriched meat products and eggs ensure tolerable amounts in humans. Poultry meats and eggs are widely consumed and their fatty acid profile and tocopherol content can be easily modified through different dietary strategies thus being excellent models to improve their nutritional value and oxidative stability.

Does feed composition affect oxidation of rainbow trout (Oncorhynchus mykiss) during frozen storage?

Rainbow trout ( Oncorhynchus mykiss ) were fed a diet containing either fish oil or rapeseed oil and with or without 200 mg/kg carotenoid (either astaxanthin or canthaxanthin). A total of six diets were obtained: (1) fish oil/astaxanthin; (2) vegetable oil/astaxanthin; (3) fish oil/canthaxanthin; (4) vegetable oil/canthaxanthin; (5) fish oil/no pigment; and (6) vegetable oil/no pigment. The fish were slaughtered and stored in polyethylene bags individually as butterfly fillets for up to 22 months at -20 °C. The composition of the fish muscle at slaughter and during frozen storage was evaluated by sampling after 4, 8, 13, 18, and 22 months. The carotenoid content in the muscle was found to be approximately 9-10 mg/kg of fish for both carotenoids. Primary oxidation lipid products (peroxides) as well as secondary oxidation products (volatiles) were measured. In addition, the level of protein carbonyl groups and the content of tocopherols and carotenoids in the muscle were also measured. To estimate the overall changes in sensory properties of the different samples during storage, a trained sensory panel also evaluated the samples. Both the sensory panel and the chemical analysis revealed that in this investigation fish fed fish oil were slightly more oxidized than fish fed vegetable oil. Results showed that canthaxanthin effectively protected both protein and lipid against oxidation during frozen storage. In contrast, astaxanthin did not seem to have a clear and systematic effect. Results indicated that the feed composition influenced the fish muscle composition and subsequently the oxidative stability of the fish during frozen storage. Besides, other constituents in the feed might influence deposition of antioxidants in the tissue and consequently affect the oxidative stability of the muscle.

Vitamin E supplementation, cereal feed type and consumer sensory perceptions of poultry meat quality

Lipid oxidation leads to meat spoilage and has been reported to cause adverse changes in the flavour and texture of poultry meat. Vitamin E has been found to be effective in delaying lipid oxidation. The aim of this study was to determine whether the vitamin E supplementation of chicken feed influences the consumers' perception of the quality of chicken meat under normal display and storage conditions. Untrained consumers (n 32) evaluated cooked breast meat from chickens (both corn fed and wheat fed) supplemented with 75 250 or 500 mg/kg vitamin E and after storage at 4°C for 4 and 7 d. Factorial analysis found an interaction between vitamin E treatment and storage day upon the perceived juiciness (P=0·023) and tenderness (P=0·041) of the chicken meat. Perceptions of quality relative to vitamin E level were more evident on day 4 than day 7. When the two cereal types were compared, the time-related sub-group effects were observed only in meat from corn-fed chickens supplemented with either 75 or 250 mg/kg, which was perceived to be juicier (P=0·018) and more tender (P=0·020) than that supplemented at the 500 mg/kg level. These results imply that the two lower concentrations of vitamin E have some advantages over 500 mg/kg, but for optimal consumer acceptance of corn-fed chicken meat, we suggest that 250 mg/kg vitamin E should be added to corn-fed poultry feed. There was no evidence to suggest any advantages in changing the current amount of vitamin E (75 mg/kg) used to rear wheat-fed birds.

Effect of dietary fat sources and zinc and selenium supplements on the composition and consumer acceptability of chicken meat

A factorial design was used to study the effect of changes in broiler feed on the composition and consumer acceptability of chicken meat. One week before slaughter, 1.25% dietary fish oil was removed from the feed and replaced by other fat sources (animal fat or linseed oil) or we continued with fish oil, and diets were supplemented with Zn (0, 300, or 600 mg/kg), and Se (0 or 1.2 mg/kg as sodium selenite or 0.2 mg/kg as Se-enriched yeast). The changes in dietary fat led to distinct fatty acid compositions of mixed raw dark and white chicken meat with skin. The fish oil diet produced meat with the highest eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) content, whereas the linseed oil diet led to meat with the highest content in total n-3 polyunsaturated acids (PUFA), especially linolenic acid. However, meat from animals on the animal fat diet was still rich in very long-chain n-3 PUFA. Se content was affected by Se and Zn supplements. Se content increased with Zn supplementation. However, only Se from the organic source led to a significant increase in this mineral in meat compared with the control. Consumer acceptability scores and TBA values of cooked dark chicken meat after 74 d or after 18 mo of frozen storage were not affected by any of the dietary factors studied.

Concentrations of cholesterol oxidation products in raw, heat-processed and frozen-stored meat of broiler chickens fed diets differing in the type of fat and vitamin E concentrations

The present study was performed to investigate the effect of dietary fat and vitamin E on concentrations of cholesterol oxidation products (COP) in broiler muscle. A total of 144 1-d-old broiler chicks were fed diets with either palm oil, soyabean oil or linseed oil and vitamin E concentrations of 20, 40 or 200 mg/kg for 35 d. COP concentrations were analysed in raw, heat-processed (180 degrees C, 20 min) and frozen-stored (-20 degrees C, 6 months) breast and thigh muscles. COP concentrations were influenced by dietary vitamin E concentration, dietary fat, treatment and type of muscle (P<0.001). Increasing the dietary vitamin E concentration generally reduced the concentration of COP. This effect was strongest in broilers fed linseed oil and weakest in broilers fed palm oil; the effect of vitamin E was also stronger in heated muscles than in raw or frozen-stored muscles. Moreover, the concentration of COP in thigh muscle was more strongly influenced by dietary vitamin E than that in breast muscle. COP concentrations in muscles were on average highest in broilers fed linseed oil and lowest in broilers fed palm oil, but the effect of the dietary fat also depended on the vitamin E concentration, the treatment and the type of muscle. In conclusion, our study shows that dietary fat and vitamin E influence the concentrations of total COP in broiler muscle. However, the effects of these factors were not only influenced by interactions between each other, but also depended on the treatment of the muscle and the type of muscle.

Influence of the dietary polyunsaturation level on chicken meat quality: lipid oxidation

The present study was carried out to evaluate the influence of increasing amounts of dietary polyunsaturated fatty acids (PUFA) and alpha-tocopheryl acetate (alpha-TA) supplementation on lipid oxidation of raw and cooked thigh meat stored under refrigeration. One hundred ninety-two female, 1-d-old, broiler chickens were randomly distributed into 16 experimental treatments resuIting from the combination of 4 levels of dietary PUFA (15, 34, 45, and 61 g/kg) and 4 levels of supplementation with alpha-TA (0, 100, 200, and 400 mg/kg). Thiobarbituric acid reactive substance (TBARS) values in cooked meat and cooked refrigerated meat were 12- and 24-fold higher, respectively, than in raw meat. Dietary polyunsaturation and alpha-TA supplementation affected lipid oxidation more markedly in cooked meat and cooked refrigerated meat than in raw meat and raw refrigerated meat. Lipid oxidation in cooked meat showed a significant linear increase as the concentration of PUFA in raw meat increased. The oxidative stability of meat was not affected by an increase in the dietary alpha-TA level from 200 to 400 mg/kg. Nonlinear relationship between TBARS values in cooked meat and alpha-tocopherol content of raw meat showed saturation in the antioxidant effect of alpha-Toc. The equation y = x (11.88 + 63.38e(-0.007z) was calculated to predict the minimum inclusion of alpha-tocopherol to diets (z) of chickens with certain dietary PUFA content (x) to assure a certain TBARS value (y).

Effect of dietary fish oil, alpha-tocopheryl acetate, and zinc supplementation on the composition and consumer acceptability of chicken meat

A factorial design was used to study the effect of dietary fish oil (1.25% and 2.5%), all-rac-alpha-tocopheryl acetate (70 and 140 mg/kg), and Zn supplementation (0 and 200 mg/kg) on the composition and consumer acceptability of chicken meat stored at -20 degrees C for 5 mo. Supplementation of the diet with all-rac-alpha-tocopheryl acetate increased the alpha-tocopherol content in meat. The fatty acid composition of the meat was affected only by the amount of fish oil. Diets supplied with 2.5% fish oil produced meat with an eicosapentaenoic and docosahexaenoic acid content double that of diets supplied with 1.25% fish oil. Zn supplementation did not affect the content of this mineral in the meat. Moreover, the consumer acceptability of meat samples showed no significant differences between dietary treatments after 5 mo of storage at -20 degrees C or with respect to a freshly cooked commercial sample used as a blind control.

Effect of dietary oregano essential oil on performance of chickens and on iron-induced lipid oxidation of breast, thigh and abdominal fat tissues

1. We studied the effect of dietary oregano essential oil (50 and 100 mg/kg of feed) on the performance of broilers, and determined the susceptibility of the resulting broiler meat to iron-induced lipid oxidation. 2. Performance of the birds was unaffected by the experimental diets. Therefore, dietary oregano oil exerted no growth-promoting effect on broilers. 3. Iron-induced lipid oxidation showed that as oregano oil increased in the diet, malondialdehyde values decreased in tissue samples, suggesting that the oil, particularly at 100 mg/kg of feed, exerted an antioxidant effect on chicken tissues. 4. Dietary alpha-tocopheryl acetate supplementation at 200 mg/kg of feed displayed greater antioxidant activity than oregano oil at either supplementation rate. 5. Thigh muscle was more susceptible to oxidation than breast muscle, although the former contained alpha-tocopherol at higher concentration. Muscle alpha-tocopherol is an important factor influencing lipid oxidation, but the influence of polyunsaturated fatty acids and content of pro-oxidants must be taken into consideration too.

Oxidative stability of dark chicken meat through frozen storage: influence of dietary fat and alpha-tocopherol and ascorbic acid supplementation

We used factorial design to ascertain the influence of dietary fat source (linseed, sunflower and oxidized sunflower oils, and beef tallow) and the dietary supplementation with alpha-tocopheryl acetate (alpha-TA) (225 mg/kg of feed) and ascorbic acid (AA) (110 mg/kg) on dark chicken meat oxidation (lipid hydroperoxide and TBA values and cholesterol oxidation product content). alpha-TA greatly protected ground and vacuum-packaged raw or cooked meat from fatty acid and cholesterol oxidation after 0, 3.5, or 7 mo of storage at -20 C. In contrast, AA provided no protection, and no synergism between alpha-TA and AA was observed. Polyunsaturated fatty acid-enriched diets (those containing linseed, sunflower, or oxidized sunflower oils) increased meat susceptibility to oxidation. Cooking always involved more oxidation, especially in samples from linseed oil diets. The values of all the oxidative parameters showed a highly significant negative correlation with the alpha-tocopherol content of meat.

Influence of dietary fat source, alpha-tocopherol, and ascorbic acid supplementation on sensory quality of dark chicken meat

We studied the influence of dietary fat source and dl-alpha-tocopheryl acetate and ascorbic acid supplementation on the sensory quality of cooked dark chicken meat stored at -20 C for different periods. Results showed that dietary fat source and alpha-tocopheryl acetate supplementation influenced sensory scores (rancid flavor and aroma and acceptability). Ascorbic acid had no influence on these scores. Thiobarbituric acid values showed a high correlation with sensory scores. In addition, the low levels of alpha-tocopheryl acetate contained in the trace mineral-vitamin mix (20 IU/kg of feed) were enough to prevent rancidity development in cooked dark chicken meat when broilers were fed a saturated fat diet and samples were vacuum-packed and stored at -20 C for 13 mo.

Efeito de níveis de vitamina E na dieta sobre o desempenho e concentração de alfa-tocoferol na carne de frangos de corte

Este experimento foi realizado com o objetivo de avaliar o efeito da suplementação de diferentes níveis de vitamina E (NVE) na dieta sobre o desempenho de frangos de corte de um a 42 dias de idade, e sobre a concentração de alfa-tocoferol (AT) na carne de peito das aves aos 45 dias de idade. Foram alojados 480 pintos de um dia, da linhagem Ross, em 16 boxes de 3,00× 2,20m, com 30 aves de ambos os sexos em cada boxe. A ração e a água foram fornecidas ad libitum. As aves receberam uma dieta inicial (1 a 21 dias), com 21,2% de PB e 2934kcal de EM/kg, e uma dieta de crescimento (22 a 42 dias), com 18% de PB e 3035kcal de EM/kg. Ambas as dietas foram suplementadas com quatro NVE: 25, 250, 500 e 750mg/kg. O delineamento experimental foi o inteiramente ao acaso, constituído de quatro tratamentos (NVE), com quatro repetições, cada uma com 30 aves. Verificou-se que o peso corporal, o ganho de peso e a conversão alimentar aos 42 dias de idade foram significativamente influenciados (P<0,05) pelos NVE utilizados na dieta. Houve aumento linear para peso e ganho de peso, e melhoria linear da conversão alimentar à medida que se elevou o nível da suplementação de vitamina E (VE) da dieta. O consumo de ração e a viabilidade não foram influenciados (P>0,05) pelos NVE. Observou-se efeito quadrático (P<0,05) do NVE na dieta sobre a deposição de AT na carne de peito das aves, sem diferença entre sexos. Máxima concentração de AT foi verificada na carne de peito de aves que foram alimentadas com dieta de 500mg de VE/kg. Desse modo, conclui-se que para cada aumento de 25mg de VE/kg na dieta, espera-se um aumento de 5,49g no peso corporal, melhoria de 0,0038 pontos na conversão alimentar, e um aumento de 8,57mig de AT/g de carne de peito de frangos de corte.

Effect of beta-carotene and vitamin E on oxidative stability in leg meat of broilers fed different supplemental fats

The objectives of this study were to investigate the effects of dietary fat (6% lard and sunflower and olive oil) and supplementation of alpha-tocopheryl acetate or beta-carotene on vitamin E content and lipid oxidation in raw, cooked, and chilled-stored broiler leg meat. Vitamin E increased its tissue level, reducing lipid oxidation. The oxidative stability of leg meat tended to decrease with dietary sunflower oil. Effects of beta-carotene on vitamin E levels and oxidation depended on dietary fat and its concentration in feed, decreasing vitamin E, mainly at 50 ppm. beta-Carotene at 15 ppm acted as antioxidant in fresh and cooked meat in the sunflower and olive oil diets. However, in stored meat, beta-carotene at 50 ppm increased TBARS, probably due to a decrease in vitamin E content and direct prooxidant effects per se. It is suggested that the antioxidant effect of beta-carotene requires the presence of vitamin E in tissues.

Comparison of effects of dietary olive oil, tallow and vitamin E on the quality of broiler meat and meat products

1. The effect of dietary fat and vitamin E supplementation on quality attributes (drip loss, oxidative stability, sensory quality) in chicken meat and meat products was investigated. Broiler chicks were fed on diets containing tallow (60 g/kg) or olive oil (60 g/kg) at a basal (30 mg/kg diet) or supplemental (200 mg/kg diet) concentration of alpha-tocopheryl acetate for 8 weeks. The alpha-tocopherol content and fatty acid composition of breast and thigh meat was determined. Drip loss was determined in breast fillets. Lipid oxidation (thiobarbituric acid-reacting substances/TBARS) and sensory quality (warmed-over flavour development/WOF) were assessed in minced thigh meat during storage. 2. Dietary olive oil increased the ratio of monounsaturated to saturated fatty acids (MUFA/SFA) in the diets. In breast and thigh, this resulted in approximately a two-fold increase in the MUFA/SFA ratio. Supplemental alpha-tocopherol increased the alpha-tocopherol content of muscles. 3. Dietary fat not influence drip loss in thawed breast fillets during refrigerated storage, but supplemental alpha-tocopherol reduced drip loss. 4. TBARS and WOF development in minced thigh meat patties were also reduced by supplemental alpha-tocopherol following frozen storage, or cooking and refrigerated storage. Storage stability was not adversely affected by dietary fat. 5. Overall, the results showed that increasing the monounsaturated profile of chicken meat lipids did not adversely affect quality characteristics. Dietary alpha-tocopherol supplementation was a more important factor in the determination of broiler meat quality.

Inclusion of oxidized vegetable oil in broiler diets. Its influence on nutrient balance and on the antioxidative status of broilers

Over a period of 4 wk, 24 10-d-old broiler hens were fed diets containing 11% vegetable oil (9% rapeseed oil, 2% soybean oil), which was added either fresh (1 meq O2/kg oil) or oxidized (156 meq O2/kg oil). The effects of the dietary treatments on nutrient digestibility were examined in a balance experiment. The antioxidative status of the animals was evaluated using plasma concentrations of thiobarbituric acid-reactive substances (TBARS), erythrocyte hemolysis in vitro, selenium-dependent and selenium-independent activity of glutathione peroxidase in liver cell cytosolic fractions, and concentrations of tocopherols and other fat-soluble compounds with antioxidative properties (lutein, beta-carotene, and retinol) in plasma and various tissues (skeletal muscle, cardiac muscle, liver, and abdominal fat). Compared to the fresh oil, the concentrations of linoleic and linolenic acid were slightly lower in oxidized oil. The concentration of alpha-tocopherol in the diet with fresh oil was an average of 80.8 mg/kg diet, whereas the diet with oxidized oil only provided 44 mg/kg. The dietary selenium content averaged 0.48 mg/kg in both diets. During the experiment, none of the animals showed symptoms of diarrhea or vitamin E deficiency. The intake of oxidized oil caused a growth depression after 2 wk. The retention of fat (P = 0.07), energy (P = 0.09), and alpha-tocopherol (P < 0.01) was lower in the group fed oxidized fat. Furthermore, these animals showed significantly higher plasma concentrations of TBARS (P < 0.01), and lower concentrations of tocopherols, lutein, beta-carotene, and retinol in plasma and tissues.