Differences in muscle histidine-containing dipeptides in broilers.

BACKGROUND: Poultry meat has high levels of histidine-containing dipeptides (HCD) and consumption of meat rich in HCD may elicit certain health benefits. The aim of this work was to compare the HCD content (anserine and carnosine) in the breast and thigh muscles of two broiler strains differing in growth rate, feeding regime, and age at slaughter. A 3 (production system) × 2 (sex) × 2 (age at slaughter) full factorial arrangement was applied with fast-growing Ross 308 chicks fed ad libitum (ROSS-AL), slow-growing Sasso T451 chicks fed ad libitum (SASSO-AL), and Ross 308 chicks given limited feeding (ROSS-LIM). At the age of 40 and 62 days, eight birds per production system × sex combination were randomly selected for sampling of the breast and thigh muscle. Muscle HCD content was determined by high-performance liquid chromatography (HPLC). RESULTS: Across treatments, levels of anserine were 2.5- and 1.9-fold higher than carnosine in breast and thigh muscle respectively (P < 0.001), and levels of anserine and carnosine were 2.2- and 2.8-fold higher respectively in breast versus thigh muscle (P < 0.001). In breast muscle, SASSO-AL had higher levels of HCD than ROSS-AL and ROSS-LIM (P < 0.001). Considering different market meat types, breast muscle of 62-day-old SASSO-AL birds had more than threefold higher content of HCD compared to thigh muscle of 40-day-old ROSS-AL birds (P < 0.001). CONCLUSION: Large differences in muscle HCD content were found, varying according to type of muscle and broiler. © 2019 Society of Chemical Industry.

Polyphenol Oxidase Containing Sidestreams as Emulsifiers of Rumen Bypass Linseed Oil Emulsions: Interfacial Characterization and Efficacy of Protection against in Vitro Ruminal Biohydrogenation.

The low transfer in ruminants of dietary polyunsaturated fatty acids to the milk or peripheral tissues is largely due to ruminal biohydrogenation. Lipids emulsified by a polyphenol oxidase (PPO) rich protein extract of red clover were shown before to be protected against this breakdown after cross-linking with 4-methylcatechol. Protein extracts of 13 other vegetal resources were tested. Surprisingly, the effectiveness to protect emulsified lipids against in vitro ruminal biohydrogenation largely depended on the origin of the extract and its protein concentration but was not related to PPO activity. Moreover, PPO isoforms in vegetal sources, effectively protecting emulsified lipids, were diverse and their presence at the emulsion interface did not seem essential. Potato tuber peels were identified as an interesting biological source of emulsifying proteins and PPO, particularly since protein extracts of industrial potato sidestreams proved to be suitable for the current application.

Supra-nutritional levels of α-tocopherol maintain the oxidative stability of n-3 long-chain fatty acid enriched subcutaneous fat and frozen loin, but not of dry fermented sausage.

BACKGROUND: Meat products enriched with n-3 fatty acids are more prone to oxidation. The aim was to investigate whether supra-nutritional levels of α-tocopherol can enhance the colour and lipid oxidative stability of n-3 fatty acids enriched dry fermented sausages, frozen loins and subcutaneous fat. Pigs were fed a diet supplemented with 18 g kg(-1) fish oil and 50, 150 or 300 mg kg(-1) α-tocopheryl acetate. The control group received 12 g kg(-1) soy oil and 150 mg kg(-1) α-tocopheryl acetate. RESULTS: α-Tocopherol levels of the frozen loin, dry fermented sausage and subcutaneous fat were elevated as a result of the dietary α-tocopherol supplementation. Lipid oxidation occurred to the same extend in the n-3 fatty acid enriched frozen loins when compared to the control group. In the subcutaneous fat enriched with n-3 fatty acids reduced lipid oxidation was found when comparing 50 mg kg(-1) versus 150 and 300 mg kg(-1) . However, in the dry fermented sausages no such effect was observed and higher TBARS values were found in the n-3 fatty acid enriched sausages compared to the control group. Colour parameters of the loin and subcutaneous fat were not affected, whereas some significant differences in the dry fermented sausages were found. The colour stability of the frozen loins was not affected by the dietary treatments. CONCLUSION: Supra-nutritional levels of α-tocopherol maintain the oxidative stability of n-3 fatty acid enriched frozen loins and subcutaneous fat, but not of dry fermented sausages. © 2016 Society of Chemical Industry.

Reducing Compounds Equivocally Influence Oxidation during Digestion of a High-Fat Beef Product, which Promotes Cytotoxicity in Colorectal Carcinoma Cell Lines.

We studied the formation of malondialdehyde, 4-hydroxy-nonenal, and hexanal (lipid oxidation products, LOP) during in vitro digestion of a cooked low-fat and high-fat beef product in response to the addition of reducing compounds. We also investigated whether higher LOP in the digests resulted in a higher cyto- and genotoxicity in Caco-2, HT-29 and HCT-116 cell lines. High-fat compared to low-fat beef digests contained approximately 10-fold higher LOP concentrations (all P < 0.001), and induced higher cytotoxicity (P < 0.001). During digestion of the high-fat product, phenolic acids (gallic, ferulic, chlorogenic, and caffeic acid) displayed either pro-oxidant or antioxidant behavior at lower and higher doses respectively, whereas ascorbic acid was pro-oxidant at all doses, and the lipophilic reducing compounds (α-tocopherol, quercetin, and silibinin) all exerted a clear antioxidant effect. During digestion of the low-fat product, the hydrophilic compounds and quercetin were antioxidant. Decreases or increases in LOP concentrations amounted to 100% change versus controls.

Determination of α-tocopherol by reversed-phase HPLC in feed and animal-derived foods without saponification.

BACKGROUND: The analysis of α-tocopherol in feed and animal-derived foods usually involves a saponification step. However, since saponification often leads to losses of α-tocopherol, a method for the determination of α-tocopherol in feed and in animal-derived foods was developed without a saponification step. RESULTS: In this method, α-tocopherol is extracted with hot ethanol and the co-extracted fat is removed by centrifugation. Removal of the fat fraction is made possible by the addition of water, to achieve an ethanol:water ratio of 40:7, followed by cooling on ice before centrifugation. This procedure allows removal of the fat fraction, while α-tocopherol is retained. Matrices differing in gross composition and α-tocopherol content were analyzed: fresh pork, cooked ham, subcutaneous fat, liver, egg yolk, milk and a compound pig feed. Higher α-tocopherol concentrations were found for this novel method compared to a conventional method with saponification, particularly for subcutaneous fat (P < 0.05). Recoveries were higher (P < 0.05) for the novel method (82-103%), compared to the saponification method (66-90%; for subcutaneous fat < 25%). CONCLUSION: Determining α-tocopherol in feed and animal-derived foods using pure ethanol without saponification results in higher extraction yields and recoveries compared to the saponification method.

Biomechanical and biochemical properties of the thoracic aorta in warmblood horses, Friesian horses, and Friesians with aortic rupture.

BACKGROUND: Thoracic aortic rupture and aortopulmonary fistulation are rare conditions in horses. It mainly affects Friesian horses. Intrinsic differences in biomechanical properties of the aortic wall might predispose this breed. The biomechanical and biochemical properties of the thoracic aorta were characterized in warmblood horses, unaffected Friesian horses and Friesians with aortic rupture in an attempt to unravel the underlying pathogenesis of aortic rupture in Friesian horses. Samples of the thoracic aorta at the ligamentum arteriosum (LA), mid thoracic aorta (T1) and distal thoracic aorta (T2) were obtained from Friesian horses with aortic rupture (A), nonaffected Friesian (NA) and warmblood horses (WB). The biomechanical properties of these samples were determined using uniaxial tensile and rupture assays. The percentages of collagen and elastin (mg/mg dry weight) were quantified. RESULTS: Data revealed no significant biomechanical nor biochemical differences among the different groups of horses. The distal thoracic aorta displayed an increased stiffness associated with a higher collagen percentage in this area and a higher load-bearing capacity compared to the more proximal segments. CONCLUSIONS: Our findings match reported findings in other animal species. Study results did not provide evidence that the predisposition of the Friesian horse breed for aortic rupture can be attributed to altered biomechanical properties of the aortic wall.

Protein oxidation affects proteolysis in a meat model system.

The effect of hydrogen peroxide-induced protein oxidation and pH (4.8 and 5.2) on meat proteolysis was investigated in a meat model system for dry fermented sausages. In oxidised samples, increased protein carbonyl contents and decreased thiol concentrations were found. The initial concentration of protein carbonyls was significantly lower in oxidised samples at pH4.8 than in ones at pH5.2, but after ten days comparable levels were reached. The inhibition of proteolysis by the addition of a protease inhibitor cocktail did not influence protein oxidation. Yet, proteolysis was negatively affected by low pH values as well as by oxidation, resulting in a reduced release of amino acids during ripening.

Effect of muscle and post-mortem rate of pH and temperature fall on antioxidant enzyme activities in beef.

The aim of this study was to investigate the effect of muscle, inner and outer Musculus biceps femoris (IBF and OBF respectively) and Musculus longissimus dorsi (LD), on the post-mortem rate of pH and temperature fall, and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) during simulated retail display. At day 0 of display (2 days post-mortem), the CAT and GSH-Px activities were lower in IBF than in OBF and LD (P<0.001), and the SOD activity was lower in OBF compared to IBF and LD (P<0.001). At day 10 of display, SOD and CAT activities had decreased in all three muscles compared to day 0 (P<0.001), whereas the GSH-Px activity did increase with time of display. Across muscles, there were significant relationships between temperature fall, colour, lipid and colour stability and antioxidant enzyme activities.

Effect of light, packaging condition and dark storage durations on colour and lipid oxidative stability of cooked ham.

The colour and lipid oxidative stability of sliced cooked ham stored at 4 °C were studied in relation to dark storage duration, lighting and packaging conditions. Colour stability was monitored by instrumental colour measurement (CIE L*a*b* colour space) whereas lipid stability was measured by the determination of the 2-thiobarbituric acid reactive substances (TBARS). A significantly higher discoloration observed in products wrapped in foil and kept in light than products wrapped in foil and kept in dark. Colour loss was estimated by loss of redness (a*), a*/b*, nitrosomyoglobin, chroma (C); or increase of lightness (L*), MetMb, hue angle (H°). Colour loss was more dependent upon photochemical process than dark storage duration and packaging types. Lipid oxidation was not significantly affected by light exposure. However lipid oxidation was significantly affected by dark storage duration as noticed from better lipid stability of products stored for short duration in dark. Better colour stability was observed on products packed in MAP with less residual oxygen.

Antioxidant enzyme activities and antioxidant capacity in longissimus muscle from bulls fed diets rich in polyunsaturated fatty acids.

The effect of a treatment diet composed of grass silage and concentrate including rapeseed (with/without feeding restriction) was compared with a control diet of maize silage/grass silage (70:30) and concentrate including soybean, on the antioxidant enzyme activities of fresh longissimus muscle from German Simmental bulls. Additionally, the effect of diet on antioxidant capacity (AOC) of hydrophilic and lipophilic antioxidants was evaluated in fresh and stored beef muscle using the FRAP-ferric reducing ability and TEAC - Trolox-equivalent antioxidant capacity assays at different reaction times. Catalase and superoxide dismutase activities were significantly higher in the treatment diet groups, and glutathione peroxidase activity was not different. AOC was not affected by the diet. However, storage affected the values of FRAP and TEAC assays, and the results were time-depending. 30min were found like a minimum reaction time for both assays. Generally, AOC values of the hydrophilic antioxidants were significantly higher than lipophilic values.

Stable carbon isotope analysis of different tissues of beef animals in relation to their diet.

As part of a larger experiment, 31 young bulls, divided into three groups, were given different diets containing either C(3) plants or a combination of C(3) and C(4) plant-based feeds in three feeding periods before slaughter. Variation in the proportion of C(4) plant material in the diets was made by including or not maize or maize-derived ingredients, whereas the other dietary constituents were from C(3) plants. Analysis of stable carbon isotope ratios (delta(13)C value) was performed on different tissues taken at slaughter: blood, plasma, liver, kidney fat, hair, muscle and ruminal contents. Blood and plasma samples were also taken at the beginning of each period. A highly significant difference was found in the delta(13)C values of blood and plasma samples taken from animals that had received a diet of only C(3) plants or with 59% C(4) material for 70 days. The delta(13)C values of all different samples taken at slaughter were highly significantly different between the three feeding groups that had received diets with 0, 13.5 or 35% C(4) material for on average 137, 139 and 83 days, respectively. For the three groups, samples of hair, muscle, plasma, whole blood and liver were significantly enriched in (13)C compared with the diet (except for liver in one group), whereas kidney fat was significantly depleted. The proportion of C(4) plant material could be accurately estimated from the delta(13)C values of different tissue samples. Stable carbon analysis of different tissues from beef animals can be used to trace back diets containing variable proportions of C(3) and C(4) plant material.

Effect of diets rich in N-3 polyunsatured fatty acids on muscle lipids and fatty acids in Belgian Blue double-muscled young bulls.

The present study was aimed at investigating the effect of duration and time of feeding n-3 fatty acids on the fatty acid composition of intramuscular fat and adipose tissue of bulls at slaughter. Four groups of bulls were given during three periods different diets, mainly differing in the presence of linseed as the predominant n-3 fatty acid source in the concentrate either or not in combination with grass (silage) as the roughage. The results show that the fatty acid composition of the feed during the earlier periods of life of the animal were important and influenced the final intramuscular fatty acid composition. Feeding n-3 PUFA during the phases before the finishing diet increased the long chain n-3 PUFA (C20:5n-3, C22:5n-3 and C22:6n-3) compared to animals which were fed only a C 18:3n-3 rich concentrate in the finishing period. The cis-9,trans-11CLA content was increased by feeding linseed in the fattening period and was mainly deposited in the triacylglycerol fraction of the intramuscular fat.