Involvement of protein degradation, calpain autolysis and protein nitrosylation in fresh meat quality during early postmortem refrigerated storage

Fresh meat quality including meat tenderness and water holding capacity are important for consumer acceptance and industry profitability in the US. Exploring the basic mechanism that regulates the development of meat quality attributes is critical for delivering consistently high quality fresh meat to consumers. The overall hypothesis of this study was that biochemical factors that influence proteolysis during the antemortem or the early postmortem period can contribute to variations in fresh meat quality. The objective was to determine the extent to which protein modifications including protein degradation, protein nitrosylation and calpain autolysis affect the development of fresh meat quality. The first experiment was designed to test the hypothesis that protein degradation and calpain activation could influence water holding capacity of fresh pork. Intensity of intact desmin was positively correlated with moisture loss, while intensity of intact integrin was negatively correlated with moisture loss during postmortem storage. Significant correlations were found between different calpain autolysis products and intensity of intact desmin and moisture loss. These results support the hypothesis that proteolysis of desmin contributes to greater water holding capacity. The second experiment hypothesized that the properties of calpains could be regulated by a nitric oxide donor S-nitrosoglutathione. S-Nitrosoglutathione could further nitrosylate y-calpain in both the absence and the presence of calcium especially at pH 6.5. The combination of S-nitrosoglutathione and calcium affected the activity of m- and y-calpain and regulated the rate of y-calpain autolysis. In the third experiment, the hypothesis that the muscle fiber type could be related to the levels of protein nitrosylation in postmortem beef was tested. Beef longissimus dorsi muscle showed higher percentage of type IIA/X and lower percentage of type I myosin heavy chain isoforms than psoas major muscle. The intensity of protein nitrosylation in longissimus dorsi muscle was greater compared to psoas major muscle in samples prepared 1 d postmortem. In conclusion, biochemical and biophysical reactions during preslaughter and postmortem storage can mediate the development of fresh meat quality during postmortem aging

Changes of Hormone Sensitive Lipase, Adipose Tissue Triglyceride Lipase, and Free Fatty Acids in Subcutaneous Adipose Tissues throughout the Ripening Process of Dry-cured Ham

Changes in adipose triglyceride lipase (ATGL) and hormone sensitive lipases (HSL) in subcutaneous adipose tissue of Xuanwei ham at different ripening stages were studied. Green hams were salted for 40 d and then ripened in a ventilated chamber for 15 months. Adipose triglyceride lipase and HSL could be detected during the whole ripening period of Xuanwei ham, but their protein levels decreased as the ripening time increased. The decrease of lipase proteins could be attributed to the decrease in protein synthesis as ripening time progressed. The level of free fatty acids (FFAs) increased at the first stage but HSL protein remained constant indicating that HSL was more important than ATGL for adipose tissues lipolysis. The main FFAs produced during the ripening period of Xuanwei ham were oleic acid, linoleic acid and palmitic acid, suggesting that the triacylglycerols containing these three FFAs were preferential substrates for ATGL and HS

Consumption of Oxidized Oil Increases Oxidative Stress in Broilers and Affects the Quality of Breast Meat

A total of 120 4-week-old broiler chickens were allotted to 12 pens and fed one of three diets including control, oxidized diet (5% oxidized oil), or antioxidant-added diet (500 IU vitamin E) for 2 weeks. Blood samples were collected at the end of feeding trial, and breast muscles were sampled immediately after slaughter. Breast meats were also collected 24 h after slaughter and used for meat quality measurements. Oxidative stress in blood, lipid and protein oxidation, and sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity of breast muscle were determined. The oxidized diet increased oxidative stress in blood and increased carbonyl content in breast meat compared with the other two dietary treatments (P \u3c 0.05). Lipid oxidation of breast muscles with the antioxidant-supplemented diet was lower than that with the oxidized and control diet groups (P \u3c 0.05). Meat from birds fed the oxidized diet showed higher drip loss after 1 and 3 days of storage and greater 0−1 h post-mortem pH decline (P \u3c 0.05). Significant differences in specific SERCA activity in breast muscles from birds fed control and oxidized diets (P \u3c 0.05) were detected. This suggested that dietary oxidized oil induced oxidative stress in live birds and increased lipid and protein oxidation in breast muscle. Decrease in SERCA activity in breast muscles due to oxidative stress in live animals accelerated post-mortem glycolysis, which sped the pH drop after slaughter and increased drip loss, indicating that oxidation of diet can cause PSE-like (pale, soft, and exudative) conditions in broiler breast muscles

Effects of Dietary Oxidation on the Quality of Broiler Breast Meat

One hundred and twenty 4-week-old broilers were randomly assigned to one of the three dietary treatments including control (none), oxidized oil (5% of diet) and antioxidants (500 IU vitamin E and 200 ppm BHT) and fed for 2 weeks. Blood samples were collected 1day before slaughter and breast muscles were sampled immediately after slaughter. Degree of lipids and protein oxidation in blood and breast muscle, and meat quality parameters were determined. Compared to control group, broilers fed diet with oxidized oil significantly increased lipid oxidation in both blood (P \u3c 0.05). Dietary oxidized oil tended to increase carbonyl content in blood and muscle (P \u3c 0.05). Addition of antioxidants significantly decreased lipid oxidation in both blood and muscle samples and arrested protein oxidation in muscle (P \u3c 0.05). Meats from oxidized oil treatment showed higher drip loss at days 1 and 3 and lower water holding capacity at day 1 than control group (P \u3c 0.05). No significant difference was found about drip loss and water holding capacity between control and antioxidant treatments. The rate of pH decline in breast meat from oxidized oil treatment was significantly higher than that of control between 0 and 1 hour after slaughter (P \u3c 0.05). However, dietary treatments did not show significant effects on body weight gain, feed consumption and feed efficiency of live birds, and cooking loss and color of breast meat. This suggested that degree of oxidation in diet increased the oxidation in blood and muscle, and the oxidative stress in live birds were related to the variations in quality parameters including pH decline, drip loss, and protein and lipid oxidation of broiler breast meat

Evaluation of the Antioxidant and Antimicrobial Activities of Porcine Liver Protein Hydrolysates Obtained Using Alcalase, Bromelain, and Papain

peer-reviewedIn order to make the by-products generated from the porcine industry more valuable, pig livers were used in this trial to obtain protein hydrolysates. Three proteases (alcalase, bromelain, and papain) were utilized for enzymatic hydrolysis with two different durations, 4 and 8 hours. Ultrafiltration process was used for the recovery of the extracts, employing three different membrane pore sizes (30, 10, and 5 kDa). The porcine livers contained considerable amounts of protein (19.0%), considering they are almost composed of water (74.1%). The antioxidant activity of the obtained hydrolysates was investigated using four antioxidant methods (2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2-2′-Azino-di-[3-ethylbenzthiazoline sulfonate] (ABTS) radical scavenging activity, ferric reducing antioxidant power assay (FRAP), and oxygen radical absorbance capacity assay (ORAC)). Antibacterial properties were also measured against Gram-negative and Gram-positive bacteria. Results indicated that the three studied factors (type of enzyme, membrane pore size, and time) significantly affected the parameters evaluated. Hydrolysates obtained at 8 hours with alcalase had the best antioxidant properties. The 30 kDa alcalase extracts exhibited the highest DPPH (562 µg Trolox/g), FRAP (82.9 µmol Fe2+/100 g), and ORAC (53.2 mg Trolox/g) activities, while for ABTS the 10 kDa alcalase showed the higher values (1068 mg ascorbic acid/100 g). Concerning the antibacterial activity, 30 kDa hydrolysates obtained with bromelain for 4 hours exhibited the highest antimicrobial capacity, providing an inhibition of 91.7%

A Comprehensive Review on Lipid Oxidation in Meat and Meat Products

peer-reviewedMeat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Nonetheless, despite lipid oxidation being widely investigated for decades, the complex reactions involved in the process, as well as the different pathways and factors that influenced them, make that lipid oxidation mechanisms have not yet been completely understood. Thus, this article reviews the fundamental mechanisms of lipid oxidation, the most important oxidative reactions, the main factors that influence lipid oxidation, and the routine methods to measure compounds derived from lipid oxidation in meat

Solution and type curves for the seepage model of the water-bearing coalbed with leakage recharge

To analyze the effects of the leakage recharge of the aquifer on the initial dewatering of coalbed methane wells, the mathematical seepage model of water in the coalbed considering the aquifer leakage was established by using the leakage coefficient according to the unsteady seepage theory. The model was solved after Laplace transform and the Stehfest numerical reverse inversion was used to obtain the solution in right space. Then, the log-log type curves of pressure and pressure derivative were created with new combinations of parameters. Based on the natural seepage mechanism, the influence of aquifer leakage on curve shape was judged. It is found that the radial flow ends earlier as the leakage coefficient increases. Moreover, it was proposed to obtain reservoir permeability, skin factor, and leakage coefficient by using type curve matching. The type curves are useful for quantitatively evaluating the level of leakage, thereby guiding the adjustment of the following production system for CBM wells.Este estudio estableció el modelo matemático de filtración de agua en una capa carbonífera al estimar la salida acuífera con el uso del coeficiente de fuga, de acuerdo con la teoría de filtración inestable, para analizar los efectos en la recarga de pérdida de fluidos de un acuífero en el drenado inicial para pozos de gas metano.  El modelo se resolvió tras usar la transformación Laplace y la inversión numérica Stehfest para encontrar la respuesta en el lugar indicado. Luego, se creó la representación algorítmica de la presión y la presión derivativa con nuevas combinaciones de parámetros. Se evaluó la influencia de la pérdida de fluido del acuífero en la forma de la curva con base al mecanismo físico de filtración. Se estableció que el flujo radial finaliza antes de que el coeficiente de pérdida de fluido se incremente. Además, se propone el uso de la curva tipo correspondiente para obtener la permeabilidad del reservorio, el factor de daño y el coeficiente de pérdida de fluido. Las curvas tipo son útiles para evaluar cuantitativamente el nivel de la pérdida de fluido, y de esta manera guiar el ajuste de un sistema de producción consecuente para pozos de gas metano de carbón

Seaweeds as promising resource of bioactive compounds: Overview of novel extraction strategies and design of tailored meat products

peer-reviewedBackground Meat and meat products have been recently perceived by consumers as unhealthy foods. To avoid this drawback, the reformulation is a feasible approach that allows obtaining custom meat-based products that incorporate compounds with certain beneficial properties for health and remove other attributes considered negative. In this framework, the edible seaweeds have been proposed to offer interesting possibilities in the meat sector to develop functional foods as they are an excellent natural source of nutrients and biocompounds with myriad functionalities. Scope and approach This review collects aspects related to the recent technologies employed to obtain and isolate biocompounds from seaweeds. The use of whole seaweeds and their bioactive extracts to develop meat foods that confer them health properties while simultaneously reducing components considered unhealthy in meat are reviewed. Furthermore, the prevention of oxidation events was also described. Key findings and conclusions Several studies have demonstrated that the incorporation of whole seaweeds and their bioactives to reformulate meat products is an excellent approach to improve certain nutritional aspects considered “bad”. However, there are still some challenges regarding the organoleptic and sensory properties of the resulting products that affect the consumer acceptability. In conclusion, more research is necessary to overcome these gaps allowing put in the market seaweeds -based meat products.Axencia Galega de Innovació