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1.
Food Chem ; 310: 125852, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31735464

RESUMO

The objective was to characterize the effect of wooden breast (WB) myodegeneration on the metabolite profile of chicken meat by 1H NMR and multivariate data analysis. The results displayed that the metabonome of chicken breast consisted predominantly of 30 metabolites, including amino acids, organic acids, carbohydrates, alkaloids, nucleosides and their derivatives. WB-affected samples showed higher leucine, valine, alanine, glutamate, lysine, lactate, succinate, taurine, glucose, and 5'-IMP levels, but lower histidine, ß-alanine, acetate, creatine, creatinine, anserine and nicotinamide adenine dinucleotide levels compared to normal fillets (p < 0.05). In conclusion, results indicated that WB-affected fillets possessed a unique biochemical signature. This unique profile could identify candidate biomarkers for diagnostic utilization and provide mechanistic insight into biochemical processes leading to WB myopathy in commercial broiler chickens.

2.
Food Chem ; 308: 125576, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31648092

RESUMO

This study investigated the effects of cold storage at different temperatures (4, -0.5, -3, and -20 °C) on protein degradation and its relationship to structural changes of black carp muscle. At -0.5 and 4 °C, major structural changes occurred, including the formation of gaps between myofibers and myofibrils, breakage of myofibrils and myofibers, and degradation of sarcoplasmic reticulum. Gel-based proteomic analysis showed that these structural changes were accompanied by degradation of a series of myofibrillar proteins, including titin, nebulin, troponin, myosin, myomesin, myosin-binding protein, and α-actinin. Loss of extractable gelatinolytic and caseinolytic protease activities was also observed. At -3 and -20 °C, formation of ice crystals was the most noticeable change. The major proteins were degraded at different locations in the black carp muscle, and gelatinolytic and caseinolytic proteases appear to contribute to the degradation of those proteins.


Assuntos
Carpas/metabolismo , Actinina/metabolismo , Animais , Proteínas de Transporte , Temperatura Baixa , Conectina/metabolismo , Cyprinidae/metabolismo , Proteínas Musculares/metabolismo , Miofibrilas/metabolismo , Miosinas/metabolismo , Proteólise , Proteômica
3.
Food Chem ; 299: 125104, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31279125

RESUMO

The role of protein denaturation in formation of thaw loss is currently not well understood. This study investigated denaturation of myofibrillar and sarcoplasmic proteins of pork loins caused by freezing-thawing in relation to freezing rate. Compared to fast freezing, slow freezing caused 28% larger thaw loss, decreased water-holding capacity of myofibrils and increased surface hydrophobicity, indicating more pronounced denaturation of myofibrillar proteins. We here propose a model: In slow freezing protons are concentrated in the unfrozen water resulting in reduced pH in proximity of structural proteins causing protein denaturation. In parallel, large ice crystals are formed outside of muscle fibers resulting in transversal shrinkage. In fast freezing small ice crystals trap protons and cause less severe protein denaturation and reduced thaw loss. Differential scanning calorimetry and tryptophan fluorescence spectra indicated sarcoplasmic protein denaturation in drip due to freezing-thawing. However, sarcoplasmic protein denaturation was independent of freezing rate.


Assuntos
Congelamento , Proteínas Musculares/química , Miofibrilas/química , Desnaturação Proteica , Carne Vermelha , Animais , Varredura Diferencial de Calorimetria , Conservação de Alimentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Gelo , Músculos Paraespinais/química , Carne Vermelha/análise , Espectrometria de Fluorescência , Triptofano/química , Água/química
4.
Crit Rev Food Sci Nutr ; 59(22): 3564-3578, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30040449

RESUMO

Protein oxidation readily occurs in postmortem muscle during storage and processing. Over the past decade new analytical methods have been developed and new aspects of protein oxidation in meat have been studied, such as the reaction mechanism, and impacts on eating quality and nutritional value. It is now evident that amino acid side chains in myofibrillar proteins undergoes modifications due to oxidative stress. In turn this will lead to formation of new protein-protein cross-links in structural proteins, however, also the overall level of fixed-charge groups attached to the peptide backbones is modified. Meat texture and water-holding are important quality attributes and they are affected by the oxidation of structural proteins. Different mechanisms have been suggested to explain the oxidation-induced quality changes, focusing mainly on reduced proteolysis and formation of cross-links. This review explores the current understanding of protein oxidation in fresh meat in relation to texture and water-holding. The consequences of protein oxidation at molecular level in relation to oxidation-induced cross-linking and changes in net charges of myofibrillar proteins, and the impacts on texture and water-holding are discussed.

5.
Meat Sci ; 145: 375-382, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30036842

RESUMO

This study aimed to determine the effect of frozen-then-chilled storage on free Ca2+, proteolytic enzyme activity of calpains and the proteasome, water-holding capacity and shear force of porcine longissimus thoracis et lumborum muscle. Pork loins were subjected to either chilled storage at 2 ±â€¯1 °C for 1, 2, 4, 6 and 9 days, or frozen-then chilled storage (-20 ±â€¯1 °C for 1 week followed by thawing overnight). Free Ca2+ increased with chilled storage in the non-frozen group. Frozen-then-chilled storage increased free Ca2+ concentration, followed by a faster decrease of calpain-1 activity and activation of around 50% of calpain-2. Proteasome activity was reduced by around 40% following freezing-thawing. Purge loss increased and water-holding capacity of myofibrils decreased in the frozen-thawed group, suggesting considerable denaturation of myofibrillar proteins. Shear force was not affected by freezing-thawing, and we speculate that the tenderizing effect of calpain activation was counteracted by loss of proteasome activity and substantial exudate loss.


Assuntos
Cálcio/análise , Calpaína/análise , Congelamento , Proteínas Musculares , Proteólise , Carne Vermelha/análise , Água , Animais , Armazenamento de Alimentos/métodos , Humanos , Músculo Esquelético/citologia , Miofibrilas , Complexo de Endopeptidases do Proteassoma , Estresse Mecânico , Suínos
6.
Meat Sci ; 143: 87-92, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29715665

RESUMO

Lard from pork back fat was dry fractionated based on crystallization temperature, resulting in fractions with a ratio of saturated to unsaturated fatty acids of 1.10 and 0.61. Lean minced pork was mixed with the saturated and unsaturated fat fraction and stored in modified atmosphere (80% O2 and 20% CO2) at 5 °C for 2, 5, 7, 9, and 12 days under light to investigate the effect on oxidative stability of lipids and proteins. The saturated fat group developed higher TBARS values and lower levels of free thiol groups during storage, indicating that the unsaturated fat fraction in minced pork promoted increased oxidative stability of both lipids and proteins. A higher content of α-tocopherol in the unsaturated fat fraction suggests that the differences in oxidative stability is causatively linked to the balance between the fatty acid composition and content of antioxidants. The TBARS values and free thiol content were negatively correlated, suggesting a relationship between lipid and protein oxidation.


Assuntos
Gorduras Insaturadas na Dieta/análise , Gorduras na Dieta/análise , Proteínas na Dieta/análise , Qualidade dos Alimentos , Produtos da Carne/análise , Estresse Oxidativo , alfa-Tocoferol/análise , Matadouros , Animais , Antioxidantes/análise , Antioxidantes/química , Proteínas na Dieta/química , Embalagem de Alimentos , Armazenamento de Alimentos , Humanos , Valor Nutritivo , Oxirredução , Estabilidade Proteica , Refrigeração , Compostos de Sulfidrila/análise , Compostos de Sulfidrila/química , Sus scrofa , Substâncias Reativas com Ácido Tiobarbitúrico/análise
7.
Meat Sci ; 143: 104-113, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29730528

RESUMO

Heat treatment of meat at temperatures between 50 and 65 °C, for extended periods of time, is known as low-temperature long-time (LTLT) cooking. This cooking method produces meat that has increased tenderness and better appearance than when cooked at higher temperatures. Public concerns regarding this method have focused on the ability to design heat treatments that can reach microbiological safety. The heat treatment induces modification of the meat structure and its constituents, which can explain the desirable eating quality traits obtained. Denaturation, aggregation, and degradation of myofibrillar, sarcoplasmic and connective tissue proteins occur depending on the combination of time and temperature during the heat treatment. The protein changes, especially in relation to collagen denaturation, along with proteolytic activity, have often been regarded to be the main contributors to the increased meat tenderness. The mechanisms involved and the possible contribution of other factors are reviewed and discussed.


Assuntos
Comportamento do Consumidor , Culinária , Preferências Alimentares , Qualidade dos Alimentos , Mastigação , Produtos da Carne/análise , Carne/análise , Animais , Fenômenos Químicos , Proteínas na Dieta/análise , Proteínas na Dieta/química , Dureza , Temperatura Alta/efeitos adversos , Humanos , Carne/efeitos adversos , Carne/microbiologia , Produtos da Carne/efeitos adversos , Produtos da Carne/microbiologia , Viabilidade Microbiana , Proteínas Musculares/análise , Proteínas Musculares/química , Pigmentos Biológicos/análise , Pigmentos Biológicos/química , Desnaturação Proteica , Estabilidade Proteica , Proteólise , Paladar , Fatores de Tempo , Água/análise
8.
Meat Sci ; 135: 102-108, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28968552

RESUMO

Hypochlorous acid (HClO) is a strong oxidant that is able to mediate protein oxidation. In order to study the effect of oxidation on charges, aggregation and water-holding of myofibrillar proteins, extracted myofibrils were oxidized by incubation with different concentrations of HClO (0, 1, 5, and 10mM). Loss of free thiols, loss of histidine and formation of carbonyls were greater with increasing oxidation level and the particle size increased. Water-holding in the 5 and 10mM HClO groups were greater than in the non-oxidized control. Isoelectric focusing (IEF) showed that the isoelectric point (pI) of oxidized proteins were lower compared to non-oxidized ones. The lower pI values of oxidized proteins suggests that oxidation increased the overall net negative charge of myofibrillar proteins solubilized for IEF. Here we propose a hypothesis that oxidation-induced increase in net negative charges is the driving force for improved water-holding in myofibrils, whereas protein cross-linking and aggregation have an opposing effect by decreasing the water-holding.


Assuntos
Proteínas Musculares/fisiologia , Miofibrilas/química , Oxirredução , Aminoácidos/análise , Animais , Histidina , Ácido Hipocloroso/farmacologia , Ponto Isoelétrico , Compostos de Sulfidrila , Suínos , Água/metabolismo
9.
Poult Sci ; 96(9): 3465-3472, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28595272

RESUMO

Recently the poultry industry faced an emerging muscle abnormality termed wooden breast (WB), the prevalence of which has dramatically increased in the past few years. Considering the incomplete knowledge concerning this condition and the lack of information on possible variations due to the intra-fillet sampling locations (superficial vs. deep position) and aging of the samples, this study aimed at investigating the effect of 7-d storage of broiler breast muscles on histology, texture, and particle size distribution, evaluating whether the sampling position exerts a relevant role in determining the main features of WB. With regard to the histological observations, severe myodegeneration accompanied by accumulation of connective tissue was observed within the WB cases, irrespective of the intra-fillet sampling position. No changes in the histological traits took place during the aging in either the normal or the WB samples. As to textural traits, although a progressive tenderization process took place during storage (P ≤ 0.001), the differences among the groups were mainly detected when raw meat rather than cooked was analyzed, with the WB samples exhibiting the highest (P ≤ 0.001) 80% compression values. In spite of the increased amount of connective tissue components in the WB cases, their thermally labile cross-links will account for the similar compression and shear-force values as normal breast cases when measured on cooked samples. Similarly, the enlargement of extracellular matrix and fibrosis might contribute in explaining the different fragmentation patterns observed between the superficial and the deep layer in the WB samples, with the superficial part exhibiting a higher amount of larger particles and an increase in particles with larger size during storage, compared to normal breasts.


Assuntos
Carne/análise , Músculos Peitorais/fisiologia , Refrigeração , Animais , Galinhas/anormalidades , Armazenamento de Alimentos , Tamanho da Partícula , Músculos Peitorais/anormalidades , Músculos Peitorais/citologia
10.
Meat Sci ; 131: 48-55, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28463752

RESUMO

The purpose of this study was to increase the knowledge on the relationship between proteolysis of myofibrillar proteins and the water-holding of meat. Myofibrils isolated from porcine longissimus thoracis et lumborum muscle were used as a model system. Myofibrils were incubated with either calpain-2, the proteasome or a lysosomal extract at 25°C for 2h. All three proteolytic systems improved the relative water-holding and generally there was a larger effect with increasing amount of enzymes in the incubation. The improved water-holding occurred in parallel to degradation of myofibrillar proteins. Desmin was degraded by calpain-2 as well as by lysosomal enzymes and α-actinin was released by the proteasome. We here propose a model in which degradation of proteins in and around the Z-disk allows overall swelling of the filament lattice and more specifically in the I-band area. In conclusion, proteolytic degradation of myofibrillar proteins by calpain-2, the proteasome or lysosomal enzymes improves the water-holding of myofibrils.


Assuntos
Calpaína/farmacologia , Miofibrilas/efeitos dos fármacos , Miofibrilas/metabolismo , Complexo de Endopeptidases do Proteassoma/farmacologia , Proteólise/efeitos dos fármacos , Carne Vermelha/análise , Água/metabolismo , Actinina/efeitos dos fármacos , Animais , Desmina/efeitos dos fármacos , Lisossomos/química , Proteínas Musculares/metabolismo , Músculo Esquelético , Sus scrofa
11.
Meat Sci ; 132: 139-152, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28552497

RESUMO

The basic contractile unit of muscle, the sarcomere, will contract as the muscle goes into rigor post-mortem. Depending on the conditions, such as the rate of pH decline, the cooling rate and the mechanical restraints on the muscles, this longitudinal shortening will result in various post-mortem sarcomere lengths as well as lateral differences in the distances between the myosin and actin filaments. This shortening is underlying the phenomena described as rigor contraction, thaw rigor, cold shortening and heat shortening. The shortening in combination with the molecular architecture of the sarcomere as defined by the myosin filaments and their S-1 and S-2 units, the interaction with the actin filaments, and the boundaries formed by the Z-disks will subsequently influence basic meat quality traits including tenderness and water-holding capacity. Biochemical reactions from proteolysis and glycogen metabolism interrelate with the sarcomere length in a complex manner. The sarcomere length is also influencing the eating quality of cooked meat and the water-holding in meat products.


Assuntos
Carne/análise , Contração Muscular/fisiologia , Sarcômeros , Actinas/química , Animais , Culinária , Qualidade dos Alimentos , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/química , Miosinas/química , Rigor Mortis , Água/química
12.
Food Chem ; 230: 475-481, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28407937

RESUMO

Minced beef was stored for 8days and myofibrillar protein (MP) was extracted to investigate the effect of oxygen concentration (0, 20, 40, 60, and 80%) in modified atmosphere packaging (MAP) on heat-induced gel properties. Compression force of gels was lower when prepared from beef packaged in 0% oxygen, intermediate in 20 to 60% oxygen and greater in 80% oxygen. Total water loss of gels prepared from beef packaged with oxygen (20-80%) was higher and rheology measurements presented higher G' and G″ values. Additionally, gels from beef packaged without oxygen exhibited higher J (t) values during creep and recovery tests, demonstrating that oxygen exposure of meat during storage in MAP affect MP in such a way that heat-induced protein gels alter their characteristics. Generally, storage with oxygen in MAP resulted in stronger and more elastic MP gels, which was observed already at a relative low oxygen concentration of 20%.


Assuntos
Embalagem de Alimentos/métodos , Oxigênio/química , Carne Vermelha/análise , Animais , Bovinos , Géis , Reologia
13.
Meat Sci ; 121: 189-195, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27341620

RESUMO

Patties were made from raw minced beef after storage for 6days in modified atmosphere (0, 20, 40, 60, and 80% oxygen) to study the combined effect of oxygen concentration and cooking temperature on hardness and color. Increased oxygen concentrations generally led to larger (P<0.01) thiobarbituric acid-reactive substances (TBARS) values, greater (P<0.01) loss of free thiols and more formation of cross-linked myosin heavy chain. Hardness of cooked patties was generally lower (P<0.01) without oxygen. Premature browning of cooked patties was observed already at a relative low oxygen concentration of 20%. The internal redness of cooked patties decreased (P<0.05) with increasing oxygen concentrations and increasing cooking temperatures. Mean particle size (D(3,2)) of homogenized cooked meat generally increased (P<0.05) with increasing cooking temperatures and increasing oxygen concentrations, and particle size was correlated (r=0.80) with hardness of cooked patties.


Assuntos
Embalagem de Alimentos , Oxigênio/análise , Carne Vermelha , Animais , Bovinos , Cor , Culinária , Concentração de Íons de Hidrogênio , Metabolismo dos Lipídeos/efeitos dos fármacos , Proteínas Musculares/análise , Tamanho da Partícula , Compostos de Sulfidrila/análise , Temperatura Ambiente , Substâncias Reativas com Ácido Tiobarbitúrico/análise
14.
Meat Sci ; 119: 32-40, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27129081

RESUMO

The role of heat-denatured sarcoplasmic proteins in water-holding is not well understood. Here we propose a new hypothesis that in PSE-like conditions denatured sarcoplasmic proteins aggregate within and outside myofilaments, improving the water-holding of denatured myofibrils. The process is compartmentalized: 1) within the filaments the denatured sarcoplasmic proteins shrink the lattice space and water is expelled; and 2) between the myofibrils and in the extracellular space, the coagulated sarcoplasmic proteins trap the expelled water from interfilamental space. The effect of sarcoplasmic proteins on the water-holding of myofibrils following incubation for 1h at 21 to 44°C was investigated. Our results were consistent with the new hypothesis. Myofibrils without sarcoplasm had the poorest water-holding. With increasing amount of denatured sarcoplasmic proteins, the water-holding of heat-denatured myofibrils improved proportionally. X-ray diffraction was used to measure the lattice space between the filaments. Precipitated sarcoplasmic proteins shrank (P<0.001) the lattice spacing by 6.3% at 44°C.


Assuntos
Carne , Proteínas Musculares/química , Miofibrilas/química , Desnaturação Proteica , Retículo Sarcoplasmático/química , Animais , Temperatura Alta , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Água/química , Difração de Raios X
15.
Food Chem ; 197(Pt A): 670-5, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26617002

RESUMO

Protein oxidation is considered an ongoing deteriorative process during storage of fresh and processed meat. Carbonyl compounds have traditionally been detected spectrophotometrically after derivatization with 2,4-dinitrophenylhydrazine (DNPH) to form protein-bound hydrazones with absorbance at 370 nm. Here we describe a novel DNPH-based method to quantify protein carbonylation in muscle and meat. The additional steps of the novel method aimed at increasing the protein solubility and inducing protein unfolding before labeling with DNPH. Compared to the traditional method, the new procedure reflected an increased protein carbonylation level measuring overall two to fourfold more carbonyls in muscles from different species as well as in soluble, salt-soluble and insoluble protein fractions. The study suggested that protein unfolding is a more important phenomenon than solubilization for increased DNPH labeling. The novel method resulted in three to fourfold larger carbonyl content determined in chicken, pork and beef (2.8, 3.6 and 3.1 nmol/mg of protein, respectively).


Assuntos
Hidrazinas/análise , Carne/análise , Músculo Esquelético/química , Carbonilação Proteica , Animais , Bovinos , Galinhas , Proteínas na Dieta/química , Análise de Alimentos , Manipulação de Alimentos , Espectrofotometria , Suínos
16.
Meat Sci ; 110: 174-9, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26241463

RESUMO

Pork loins were stored at 5°C for 14 days to investigate the effect of oxygen concentration in modified atmosphere packaging (MAP) on shear force and oxidation of lipids and proteins. The modified atmosphere contained 0 to 80% O2, 20% CO2, and balanced with N2. The results showed that shear force and thiobarbituric acid-reactive substances (TBARS) values increased with increasing oxygen concentration. Protein oxidation when measured as loss of free thiol groups, was greater in meat packaged under oxygen (20-80%). Myosin heavy chain (MHC) cross-linking, another marker of protein oxidation, was greater in MAP with 80% oxygen than 0% and 20% oxygen. Desmin degradation was not affected by the presence of oxygen, suggesting that the mechanism of oxygen-induced toughening of meat is through protein oxidation leading to cross-linking of structural proteins rather than through inactivation of proteolytic enzymes leading to reduced proteolysis.


Assuntos
Embalagem de Alimentos/métodos , Carne/análise , Oxigênio , Animais , Desmina , Conservação de Alimentos , Oxirredução , Resistência ao Cisalhamento , Compostos de Sulfidrila , Suínos , Substâncias Reativas com Ácido Tiobarbitúrico
17.
Asian-Australas J Anim Sci ; 28(8): 1178-86, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26104527

RESUMO

Lipid oxidation, colour stability and physico-chemical quality of pork frankfurters with the incorporation of 0.30% sea buckthorn (SBT), 0.10% grape seed (GSE), 0.03% green tea (GTE), 0.12% fenugreek seed (FSE) and 0.10% Acacia catechu (ACE) were studied during 20 days of refrigerated aerobic storage. The SBT and ACE were identified as being the most effective antioxidants to retard lipid oxidation with the potency decreasing in the following order: SBT>ACE>GSE>GTE>FSE based on thiobarbituric acid reacting substances, peroxide value and free fatty acids. In all samples pH and aw decreased during storage period. The L* value of treated as well as control samples decreased over time while SBT and ACE exhibited an increased redness producing higher a* values than other treatments. However, GTE was more effective in increasing b* values than other treatments at the end of storage. The results suggest that functional plant-derived extracts can be valuable to the modification of frankfurter formulations for improved oxidative stability as well as quality characteristics.

18.
Meat Sci ; 98(2): 124-8, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24927048

RESUMO

Denaturation of myofibrillar proteins in porcine longissimus thoracis et lumborum muscle was investigated after pre-rigor temperature incubation at 20, 30 and 40°C. At 24h myofibrils were isolated and myosin was further cleaved by chymotrypsin. High temperature pre-rigor induced release of myosin S1 (subfragment-1), less (P < 0.05) Ca(2+)-ATPase activity and structural alterations of the region of the myosin molecule that harbors S1. Surface hydrophobicity of myofibrils from the 40°C group increased (P<0.001), suggesting a temperature-induced structural rearrangement exposing hydrophobic groups on the surface of myofibrils which in turn may explain the reduced water-holding of PSE meat.


Assuntos
Temperatura Alta , Carne/análise , Músculo Esquelético/química , Subfragmentos de Miosina/química , Desnaturação Proteica , Animais , ATPase de Ca(2+) e Mg(2+)/metabolismo , Quimotripsina/metabolismo , Eletroforese em Gel de Poliacrilamida , Interações Hidrofóbicas e Hidrofílicas , Miofibrilas/química , Suínos
19.
Meat Sci ; 93(4): 787-95, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23305828

RESUMO

The aim of the current study was to elucidate whether cows and young bulls require different combinations of heating temperature and heating time to reduce toughness of the meat. The combined effect of heating temperature and time on toughness of semitendinosus muscle from the two categories of beef was investigated and the relationship to properties of connective tissue was examined. Measurements of toughness, collagen solubility, cathepsin activity and protein denaturation of beef semitendinosus heated at temperatures between 53°C and 63°C for up to 19 1/2 h were conducted. The results revealed that slightly higher temperatures and prolonged heating times were required to reduce toughness of semitendinosus from cows to the same level as in young bulls. Reduced toughness of semitendinosus as a result of low temperature for prolonged time is suggested to result from weakening of the connective tissue, caused partly by denaturation or conformational changes of the proteins and/or by solubilization of collagen.


Assuntos
Colágeno/química , Tecido Conjuntivo/química , Manipulação de Alimentos/métodos , Temperatura Alta , Carne/análise , Desnaturação Proteica , Estresse Mecânico , Animais , Bovinos , Dieta , Feminino , Humanos , Masculino , Proteínas Musculares/química , Solubilidade , Temperatura Ambiente
20.
Meat Sci ; 91(1): 50-5, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22226362

RESUMO

The experiment was conducted to determine the effect of temperature during post-mortem muscle storage on the activity of the calpain system, the myofibril fragmentation and the free calcium concentration. Porcine longissimus muscle were incubated from 2h post-mortem at temperatures of 2, 15, 25 and 30 °C and sampling times were at 2, 6, 24, 48 and 120 h post-mortem. After 120 h at 30 °C the free calcium concentration increased to 530 µM from 440 µM at 2 °C. Incubation at temperatures higher than 2 °C resulted in the appearance of autolyzed m-calpain activity and a decrease of native m-calpain activity. Native m-calpain decreased more slowly than native µ-calpain, and the autolysis process started later. Myofibril fragmentation increased with storage time and incubation temperature, while calpastatin activity decreased. The study showed that high temperature incubation not only rapidly activated µ-calpain but at higher temperatures and later time points also m-calpain.


Assuntos
Proteínas de Ligação ao Cálcio/farmacologia , Calpaína/metabolismo , Inibidores de Cisteína Proteinase/farmacologia , Manipulação de Alimentos , Carne/análise , Músculo Esquelético/enzimologia , Animais , Autólise/prevenção & controle , Cálcio/análise , Proteínas de Ligação ao Cálcio/isolamento & purificação , Calpaína/antagonistas & inibidores , Calpaína/isolamento & purificação , Inibidores de Cisteína Proteinase/isolamento & purificação , Músculo Esquelético/química , Músculo Esquelético/efeitos dos fármacos , Miofibrilas/química , Miofibrilas/efeitos dos fármacos , Miofibrilas/metabolismo , Tamanho da Partícula , Proteólise/efeitos dos fármacos , Sarcômeros/química , Sarcômeros/efeitos dos fármacos , Sarcômeros/metabolismo , Sus scrofa , Temperatura Ambiente , Fatores de Tempo
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