Effect of dietary antioxidant and fatty acid supply on the oxidative stability of fresh and cooked pork

Sex Does Not Affect the Colour, Shear Stress, and Lipid Oxidation of Pork Meat, but Feed-Added Plant-Derived Extracts, Storage Time and Packaging Type Do

Essential plant oils added to products, packaging or animal feed are used as a method of preserving food quality because they extend the shelf-life of meat due their antioxidant and/or antimicrobial capacity. This action can be achieved with the correct packaging that preserves the meat's quality and safety. This study investigates the effects of plant-derived extracts (PDE) on the meat quality and shelf-life of pork packaged in vacuum or modified atmosphere packaging (MAP). Thirty-six barrows and thirty-six gilts were allocated into three experimental groups: the control, garlic extract (1 kg/ton of feed) and oregano-rosemary oil (2 kg/ton of feed) with the same base-diet. Two packaging were used: vacuum and a commercial MAP (70% O₂, 30% CO₂). The meat fat content, pH, colour, TBARS values and Warner-Bratzler shear stress were investigated. The sex of the animals did not affect any of the studied variables, whereas PDE affected some of the colour variables and the shear stress; both the packaging type and the storage time affected the colour variables, lipid oxidation and shear stress. Vacuum-packed meat was more stable in terms of colour, lipid oxidation and shear stress than MAP-packed meat.

Combined effect of ultrasound and basic electrolyzed water on the microbiological and oxidative profile of low-sodium mortadellas

Ultrasound (US) and basic electrolyzed water (BEW) are considered emerging technologies; however, few studies have addressed the combination of both technologies in emulsified meat products. This study aimed to evaluate the individual and combined effect of US (25 kHz; 175 W; 20 min) and BEW (pH 10.99; -92.33 mV) on the microbiological and oxidative profile of low-sodium mortadellas (30% of NaCl reduction) stored for 90 days at 5 °C. The use of BEW alone increased the pH and reduced the redox potential of mortadellas, while the US did not affect these parameters. The combined application of US and BEW reduced the lactic acid bacteria counts by up to 0.36 log CFU/g. In addition, BEW stimulated the growth of lipolytic bacteria. The treatments subjected to US application alone showed a lower growth rate of lipolytic bacteria, lower lipid and protein oxidation, and higher ΔE* values. Therefore, the application of US and BEW may be a promising strategy to improve the microbiological and oxidative quality of mortadella during storage.

Estimation of the total antioxidant potential in the meat samples using thin-layer chromatography

There is limited literature on the antioxidative properties of food of animal origin. Measurements of antioxidative properties are usually performed using the reaction of reduction of colored 2,2-diphenyl-1-picrylhydrazyl (DPPH) radials. Changes of the DPPH color are tracked photometrically. These measurements are interfered by both, the tested samples and reduced DPPH. This study aims to demonstrate the ability to separate different forms of DPPH (DPPH• and DPPH-H) by thin-layer chromatography (TLC). Further, it has been practically applied in the study of the determination of antioxidative properties of the meat samples. It was found that TLC can be used for the separation of different forms of DPPH as well as for measurement of TAP (total antioxidant potential) values related to the DPPH•. The strongest antioxidant properties were observed for pork neck extracted in buffer pH 2 and for smoked salmon fish extracted in acetone, the lowest for veal and turkey fillet extracted in methanol.

Antioxidative Activity of Thyme (Thymus vulgaris) and Oregano (Origanum vulgare) Essential Oils and Their Effect on Oxidative Stability of Minced Pork Packaged Under Vacuum and Modified Atmosphere

The antioxidant stability of minced pork treated with thyme and oregano essential oils (EOs) was determined. Minced pork containing different concentrations (0%, 0.3%, 0.6%, or 0.9%) of thyme (TEO) or oregano essential oil (OEO) and packaged under vacuum or modified atmosphere (MAP) (30%O₂ /50%CO₂ /20%N₂ ) was evaluated within 15 days of refrigeration (3 ± 1 °C) storage. EOs were examined for scavenging capacity toward 2,2-diphenyl-1-picrylhydrazyl, nitric oxide radicals, and hydroxyl, and inhibition of lipid peroxidation and ferric ion reducing antioxidant power (butylated hydroxytoluene was used as positive controls). The order of antioxidative effectiveness was as follows: butylated hydroxytoluene > OEO > TEO, with significant differences between agents (P < 0.05). Lipid oxidation in meat was determined by monitoring malondialdehyde (MDA) formation and lipolysis was assessed by measuring the acidity index immediately and after 3, 6, 9, 12, and 15 days of storage. EOs significantly (P < 0.05) increased the stability of minced pork with respect to lipid oxidation compared with the control, and the antioxidative effect was dose-dependent. Moreover, vacuum packaging resulted in mince with significantly lower oxidation and lipolysis levels than modified atmosphere packaged mince (P < 0.05). The results demonstrate that both EOs examined effectively reduced lipid oxidation in raw pork mince after 2 weeks' storage. PRACTICAL APPLICATION: The natural food preservatives market is growing rapidly, as is high demand for organic foods. These results are likely to be of interest to the scientists, researchers, and persons who work in the meat industry. Results and discussion can contribute to a better understanding of antioxidative properties of essential oils in food model. Furthermore, no study has reported the effect of these MAP on pork oxidative stability.

The investigation of alfaalfa effect on the activity of superoxide dismutase in chicken meat in dependence on time storage

This study was conducted in order to monitor the effect of adding lucerne meal to chicken feed mixtures. The experiment was conducted at the Department Food Hygiene and Safety, Faculty of Biotechnology and Food Science, Slovak University of Agriculture in Nitra. Chickens for meat production - final type Cobb 500 were used in the experiment. Chickens were placed in boxes all together for one group at the beginning of the experiment and from 14 days of age chickens were divided individually into floor enriched cages. Feeding of chickens lasted 38 days. The experiment was carried out without sex segregation. For the production of a feed composition was used alfalfa (Medicago sativa) as lucerne meal, which was added to the feed at a rate of 4%, namely: starter (HYD-01), growth (HYD-02) and final (HYD-03). The control group did not include the addition of lucerne meal. Chickens were fed ad libitum. Chickens were slaughtered after completion of feeding and the meat samples were taken for analysis. The collected samples were stored at -18 °C. Collected samples of meat were analyzed after slaughter chickens at time intervals of 6, 12 and 18 months. In the experiment was monitored the content of supeoxid dismutase in the chicken meat depending on the length of storage time. Superoxide dismutase content was increasing by storage time, while there were some statistically significant differences between groups.

The intrinsic cause of color fading in sliced cooked cured beef during chilled storage

The relationship between color change and other physical and chemical characteristics of sliced cooked cured beef (SCCB) during chilled storage were investigated using principal components analysis (PCA) to determine the color fading causes. Samples were prepared and stored at 8°C for up to 35 days in a vacuum package to simulate a supermarket storage environment; related indicators were measured periodically every week. The results showed that the first PC explained 59.82% of the total variation, and the second explained 22.28%. PC1 was a concentrated reflection of color changes of SCCB during storage and PC2 was an environment factor causing the change of color. The change in apparent redness is mainly caused by redox reaction of the nitroso hemochromogen (NH) (eigenvectors of a*, C and NH in PC1 were all the maximum value of 0.28); a* was correlated with NH (0.96), free sulfhydryls (0.98), carbonyl derivatives (-0.95) formed during protein oxidation, and malondialdehyde (-0.98) and dienes (-0.92) formed by lipid oxidation. Color fading was significantly correlated with oxidizing and reducing power, existing forms of nitrogen and with the pH of the meat matrix. Changes in the internal environment of the sample initially influenced L* and b* values, and subsequently a*.

Lipid stability, antioxidant potential and fatty acid composition of broilers breast meat as influenced by quercetin in combination with α-tocopherol enriched diets

Background

Dietary supplementation of antioxidants is a vital route to affect the oxidative stability and fatty acid profile of broiler meat. The supplementation of feed with antioxidants decreases degradation of lipids in muscles thereby enhances meat stability.

Methods

The present study was carried out to investigate the influence of dietary quercetin in combination with α-tocopherol on growth performance, antioxidant potential, lipid stability and fatty acid composition in breast meat of birds. Accordingly, one day old 300 Hubbard strain male broiler birds were given three levels of quercetin @100, 200 and 300 mg/kg feed in combination with α-tocopherol @150, 225 and 300 mg/kg feed. The resultant meat was subjected to antioxidant assay, lipid stability, quantification of antioxidants followed by fatty acid profile of broiler breast meat.

Results

The results explicated that feed treatments imparted momentous effect on gain in weight, and feed conversion efficiency however, intake of feed in birds affected non-momentously. The highest weight gain recorded in T9 as 2374.67 & 2388 g/bird followed by T8 & T6 2350 & 2353.33 and 2293.33 & 2307 g/bird, respectively whilst the lowest in T0 as 1992.67 & 1999 g/bird during the experimental year 2013 and 2014. The results regarding antioxidant potential revealed that among treatments, T9 exhibited highest values for total phenolic contents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) & ferric reducing antioxidant power assay (FRAP) i.e. 158.70 ± 0.84 mg GAE/100 g, 82.40 ± 0.93 % and 682 ± 2.11 μmol/Fe^+2/g, respectively as compared to T0 104.27 ± 1.64 mg GAE/100 g, 54.71 ± 0.64 % and 542.67 ± 1.74 μmol/Fe⁺² /g of meat, correspondingly. The TBARS assay indicated that malondialdehydes production in meat increased during storage however, antioxidants deposition varied significantly among treatments. Fatty acid compositional analysis revealed that addition of quercetin with α-tocopherol in the bird’s diet decreased the fatty acid generation particularly saturated fatty acids.

Conclusion

Conclusively, dietary supplementation of quercetin along with α-tocopherol improves growth performance, antioxidant capacity, stability of lipids and fatty acid composition in breast meat of birds.

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation in cooked pork meat patties enriched with n-3 fatty acids

BACKGROUND

The effect of olive leaf extracts on lipid and protein oxidation of cooked pork patties refrigerated stored for 9 days was evaluated. Patties were prepared from longissimus dorsi muscle of pigs, and dietary supplemented with linseed oil.

RESULTS

Results showed that dietary linseed oil modified the fatty acid composition of pork patties by increasing (P ≤ 0.05) n-3 (α-linolenic acid) and decreasing (P ≤ 0.05) n-6 (linoleic acid) fatty acids. Olive leaf extracts at supplementation levels of 200 and, especially, of 300 mg gallic acid equivalents kg⁻¹ meat, delayed lipid oxidation by reducing (P ≤ 0.05) both primary (conjugated dienes and hydroperoxides) and secondary (malondialdehyde) oxidation products. They also inhibited protein oxidation in a concentration-dependent manner by reducing (P ≤ 0.05) protein carbonyls and increasing (P ≤ 0.05) protein sulfhydryls. In addition, they improved sensory attributes of the n-3 enriched patties.

CONCLUSION

Results suggested that olive leaf extracts might be useful to the meat industry as an efficient alternative to synthetic antioxidants.

Application of KRL test to assess total antioxidant activity in pigs: sensitivity to dietary antioxidants

The application of Kit Radicaux Libres (KRL) test to assess total blood antioxidant activity in pigs was evaluated. The KRL has been validated and is widely used in humans for assessing the effectiveness of natural or pharmaceutical treatments, and in vitro to evaluate the antioxidant activities of natural or synthetic antioxidants. In this study the sensitivity of the KRL test in assessing the effectiveness of dietary antioxidant supplementation (vitamin E and plant extract) was evaluated in two different phases of pig breeding. The first trial, in post-weaned piglets (40 piglets/group) fed dietary vitamin E supplementation for 60 days, indicated that there was a higher total antioxidant activity (P=0.032) of whole blood and of red blood cells (P=0.001) than for control pigs. The second trial indicated that long-term supplementation of water soluble plant extract (20 pigs/group) from the leaves of Verbenaceae (Lippia spp.) tended (P=0.091) to increase antioxidant activity in the whole blood of treated, rather than control pigs. These results indicate that the KRL might be recommended as one of efficient means for evaluating antioxidant activity of dietary ingredients fed to pigs.

Lipid and protein oxidation of α-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or α-tocopheryl acetate

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or α-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with α-linolenic acid through diet supplementation with linseed oil enhanced (p≤0.05) lipid oxidation in both raw and cooked chops but had no effect (p>0.05) on protein oxidation during refrigerated storage while decreasing (p≤0.05) the sensory attributes of cooked pork. Diet supplementation with olive leaves or α-tocopheryl acetate had no effect (p>0.05) on the fatty acid composition of pork but decreased (p≤0.05) lipid oxidation while exerting no effect (p>0.05) on protein oxidation in both raw and cooked α-linolenic acid-enriched chops stored and chilled for 9 days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10 g/kg and 200mg/kg diet, respectively, exerted (p≤0.05) a beneficial effect on the sensory attributes of cooked α-linolenic acid-enriched pork chops.

Changes in the color of white chocolate during storage: potential roles of lipid oxidation and non-enzymatic browning reactions

Three different samples of white chocolate were prepared: a sample with a synthetic antioxidant, another with casein peptides as natural antioxidant, and a third sample without any kind of antioxidant. Parameters associated with lipid oxidation and non-enzymatic browning were evaluated in the different samples of white chocolate during 10 months storage at 20 and 28°C. Acidity, thiobarbituric acid reactive substances and peroxide values increased with the incubation time. Samples stored at 20°C often showed lower values for these parameters than those stored at 28°C, although the differences were not always significant. The values for water activity increased from 0.4 to 0.53-0.57 during the period of 10 months. The color parameter a* was increased in samples stored at 28°C from month 5, and the parameter b* was lower in samples containing antioxidants from month 2. The addition of antioxidants did not significantly influence most the parameters studied, suggesting that the main parameters governing the alterations of white chocolate during its shelf-life was the storage temperature and increase in water activity.

Effect of cooking on protein oxidation in n-3 polyunsaturated fatty acids enriched beef. Implication on nutritional quality

The effect of cooking on protein oxidation was investigated in M. Longissimus thoracis of eight Normand cows fed during a 100 days finishing period with two different diets: a conventional diet (concentrate/straw based diet) and a diet rich in n-3 polyunsaturated fatty acids (PUFAs), obtained by addition to the conventional diet of a mixture of extruded linseed and extruded rapeseed. After 11 days storage, at 4 degrees C under vacuum, meat was cooked by applying jets of steam. Three experimental heating treatments were tested: two with constant surface temperatures of 65 and 96 degrees C during 300s, and one with a continuous increasing surface temperature up to 207 degrees C. Protein oxidation was evaluated by the measurement of carbonyls, aromatic amino acids, and free thiols content. The formation of Schiff bases due to the reaction of proteins with aldehydic products of the lipid oxidation was also evaluated. Cooking resulted in a significant increase of carbonyl groups and Schiff bases as well as a significant degradation of tyrosine and tryptophan. Nevertheless, enrichment of the animal diet in n-3 PUFAs had minor effects on protein oxidation induced by cooking which are unlikely to be of nutritional significance.

Influence of different dietary doses of n-3- or n-6-rich vegetable fats and alpha-tocopheryl acetate supplementation on raw and cooked rabbit meat composition and oxidative stability

This study evaluates the effects of replacing beef tallow added to rabbit feeds (3% w/w) by different doses (0%, 1.5% and 3% w/w) of n-6- or n-3-rich vegetable fat sources (sunflower and linseed oil, respectively) and alpha-tocopheryl acetate supplementation (0 and 100 mg/kg) on the fatty acid composition, alpha-tocopherol content, and oxidation levels [assessed by analyzing thiobarbituric acid (TBA) and lipid hydroperoxide values] in rabbit meat. We also measured these parameters after cooking and refrigerated storage of cooked rabbit meat. Both dietary alpha-tocopheryl acetate supplementation and the dose and source of fat added to feeds influenced meat fatty acid composition, modifying the n-6/n-3 ratio, which was more nutritionally favorable when linseed oil was used. Furthermore, the addition of linseed oil and the supplementation with alpha-tocopheryl acetate enhanced long-chain PUFA biosynthesis. However, the addition of 3% linseed oil increased meat oxidation, and although it was reduced by dietary supplementation with alpha-tocopheryl acetate in raw meat, this reduction was not as effective after cooking. Therefore, dietary supplementation with 1.5% linseed oil plus 1.5% beef tallow and with alpha-tocopheryl acetate would be recommended to improve the nutritional quality of rabbit meat.

Effect of dietary rosemary and α-tocopheryl acetate on the oxidative stability of raw and cooked pork following oxidized linseed oil administration

The effect of a 2% dietary administration to pigs of oxidized linseed oil (targeted level of 150mEq.O(2)/kg oil after heating at 50°C and exposure to air for 3-4 days following addition of 10ppm CuSO(4)), either or not in combination with antioxidants, on the oxidative stability of raw and cooked pork during illuminated chill storage was assessed. The antioxidant treatments were: 40ppm α-tocopheryl acetate, 40ppm rosemary extract, 40ppm rosemary extract+2ppm gallic acid, and 40ppm α-tocopheryl acetate+40ppm rosemary extract. A total of 20ppm of α-tocopheryl acetate (ATA) was added to all diets in order to meet the physiological requirement of the animals. The antioxidant treatments did not exert any effect on colour and protein oxidation. Lipid oxidation was only decreased by dietary ATA when comparing the ATA supplemented groups combined versus a control treatment group for raw but not for cooked meat. This was due to a higher content of α-tocopherol in the meat and subcutaneous fat. The lipid oxidation results suggested a lack of antioxidant effect for the rosemary extract. No evidence for a synergistic effect of the antioxidant combinations was observed.