Biochemical and Utralmicroscopic Evaluation of Myofibril Proteins and Collagen during Ageing in Broiler Chicken PSE (Pale, Sof, Exudative) Meat

Abstract The aim of this work was to study the myofibril proteins and collagen fraction changes in broiler chickens PSE (pale, soft, exudative) meat during ageing and their relationship to meat quality. The results presented an increase of myofibril proteins and collagen solubility promoted by the enhanced proteases activities during storage. Ultramicroscopically, the PSE meat samples revealed intracellularly a sarcomere super contraction and lacunas within the A and I bands while Z-lines appeared very dense and fragmented in comparison to normal samples. This observation was noticed already at 4h storage while extracellularly collagen fibrils decreased visually within the endomysium only after 24h of conditioning. These results influenced the quality as the PSE meat presented better functional properties at the first hours of conditioning before further proteins degradation by proteases. Thereafter, at the later ageing stage a further disintegration of the abnormal meat structure would affect the meat functional properties.

Turkey Meat. Seasonal Effect on Meat Quality and on Dead on Arrival Index in a Commercial Plant

ABSTRACT The objective of this study was to determine the incidence of Pale, Soft, Exudative (PSE) meat and to characterize the Dark, Fim, Dry (DFD) meat as well as the Dead on Arrival (DOA) index in a commercial turkey slaughterhouse in southern Brazil during the summer and winter seasons. The journeys (n=64) were over a distance of 36 ± 20 km and took approximately 95 ± 20 min. Color (L*) and pH distribution of turkey breast meat (n=5,352) were evaluated from different farms (n=64) during the 2015-2016 years. The pH, water-holding capacity, color (L*, a*, b*) were used to establish cutoff values for DFD meat (L* < 44.0 and pH > 5.90) and presented correlation among them. The L* value was the highest during the summer (P<0.01), indicating the highest incidence of PSE meat (28.35 %), and lowest during winter, observing the highest incidence of DFD meat (10.3 %). Finally, the obtained summer DOA index was 0.23 % higher in relation to winter.

Influence of Cooling on the Glycolysis Rate and Development of PSE (Pale, Soft, Exudative) Meat

The aim of this work was to evaluate pH values fall rate in chicken breast meat under commercial refrigeration processing conditions and the development of PSE (pale, soft, exudative) meat. Broiler breast samples from the Cobb breed, both genders, at 47 days of age (n = 100) were taken from refrigerated carcasses (RS) immersed in water and ice in a tank chilled at 0°C (±2). pH and temperature (T) values were recorded at several periods throughout refrigeration in comparison to samples left at room T as control (CS). The ultimate pH (pHu) value of 5.86 for RS carcasses were only reached at 11°C after 8.35 h post mortem (PM) while, for CS samples, pHu value was 5.94 at 22°C after 4.08 h PM. Thus, under commercial refrigeration conditions, the glycolysis rate was retarded by over 4.0 h PM and the breast meat color was affected. At 24.02 h PM, PSE meat incidence was 30% while for CS, meat remained dark and PSE meat was not detected. Results show retardation in the glycolysis rate and PSE meat development was promoted by the refrigeration treatment when compared with samples stored at processing room temperature.

Broiler chicken PSE (Pale, Soft, Exudative) meat and water release during chicken carcass thawing and brazilian legislation

The objective of this work was to investigate the relationship between poultry PSE meat and water loss of frozen chicken carcass in two experiments. The first experiment was carried out in commercial abattoir. Poultry carcass were classified as PSE meat (n=59) (pH <5.8) and control samples (n=55) (pH >5.8). Water absorption and drip test were performed according to the Brazilian legislation methodologies. The second experiment was carried out with commercial whole five brands frozen carcasses purchased from the local supermarkets (n=30) and analyzed for pH, water holding capacity (WHC) and drip test. PSE poultry meats absorbed 3.59% of water during the processing similar to the control samples; however, released 0.38% more water during thawing of the carcasses. From these five brands evaluated, three presented drip values above 6.0%. The highest drip value was showed by the brand sample that had pH and WHC values characteristics of PSE meat. It could be postulated that PSE meat phenomenon promoted more water release during thawing leading to a misinterpretation in relation to the Brazilian legislation for water carcass liberation during thawing.

Commercial preslaughter blue light ambience for controlling broiler stress and meat qualities

The objective of this work was to study the effect of blue light diffuser on the broiler stress control by measuring the occurrence of PSE meat just before slaughtering. Birds were divided into the following two groups before slaughter at the point of being hung on shackles: broiler group under low intensity blue light ambience (475, 17-20 lx) and control group under white light (550-650nm, 321-332 lx). Birds' stressful conditions were measured by the occurrence of PSE meat. Breast fillets were classified as PSE meat based on pH (<5.8) and lightness (L*> 53.0). The fillet samples in the control group had the following characteristics: pHu=5.77, L* = 54.26 and b*= 6.27. The fillet samples from birds under blue light ambience had the following characteristics: pHu=5.81, L* = 52.86 and b* = 5.22 (p < 0.05). These results revealed that the treatment of blue light ambience just before slaughtering contributed to the alleviation of ante mortem stress of the birds, which was observed by a 14% decrease in the occurrence of PSE meat. Exposure to blue light just before slaughtering was shown to have potential to be used in modern slaughterhouses to offer a comfortable atmosphere, thereby maintaining breast meat quality.

Effect of carrageenan addition on the yield and functional properties of charqui (Jerked Beef)

The objective of this work was to evaluate the application of carrageenan (CAR) to improve the functional properties of the jerked beef (JF) and to increase its processing yield. JB produced from Vastus lateralis with CAR (1.0%) at 25ºC and NaCl (15.0%) had approximately 15.0% higher moisture and a 32.0% higher processing yield in comparison to the control samples.JB-CAR presented shear force approximately 5.0 and 20% lower in the samples uncooked salted and desalted cooked, respectively, and sensorial acceptance above 80%. The results demonstrated the possibility of applying carrageenan to jerked beef in order to obtain an increase in the processing yield and a tender product while maintaining the sensorial quality and its intermediate-moisture meat product nature.

Lipid and protein oxidation in charqui meat and jerked beef

In this study, the changes in the lipid (Lox) and protein oxidation (Pox) were measured quantitatively by TBARS and carbonyl methods, respectively, throughout the salting and drying steps of charqui meat (CH) and jerked beef (JB) preparation and their storage up to 60 days. The experiment was carried out on CH samples treated with brine (20.0%) and JB with same brine solution added with sodium nitrite (0.02%). After 60 days of storage, the carbonyl substances in CH were 2.77nmol mg-1 while in the JB samples, there was 61.0% oxidation inhibition. The TBARS determination revealed a Lox inhibition by approximately 5-fold in the latter samples. These results indicated that in the metmyoglobin molecule, the nitrite kept the Fe in the Fe2+ state in JB samples whereas in CH, the Fe was oxidized to Fe3+, which catalyzed the oxidation reactions more efficiently, leading to the higher development of Lox and Pox.

APLICAÇÕES TECNOLÓGICAS E ALTERNATIVAS PARA REDUÇÃO DO CLORETO DE SÓDIO EM PRODUTOS CÁRNEOS / TECHNOLOGY APPLICATIONS AND ALTERNATIVES TO REDUCE SODIUM CHLORIDE IN MEAT PRODUCTS

O objetivo deste trabalho foi revisar as aplicações tecnológicas e alternativas para redução do uso de cloreto de sódio em produtos cárneos. Foram abordadas as características do consumo de cloreto de sódio, destacando sua ação hipertensiva, as aplicações tecnológicas do cloreto de sódio em produtos cárneos, incluindo a promoção do gosto salgado, seu efeito sobre a atividade de água e a estabilidade microbiológica, além da sua influência nas propriedades funcionais das proteínas cárneas. Também foram apontados os métodos disponíveis para redução dos níveis de NaCl nos derivados cárneos, como o uso de sais não sódicos, novos ingredientes e métodos de conservação alternativos. A preocupação dos consumidores relacionada aos efeitos prejudiciais à saúde, associada ao consumo excessivo de sódio, exigirá das indústrias alimentícias continua redução do uso de sal nos alimentos. Essa limitação enfrenta maior complexidade no segmento cárneo, pois além de prover palatabilidade, o NaCl é responsável por diversas propriedades funcionais. A busca de alternativas para redução do uso de NaCl, sem prejuízo para a qualidade sensorial dos produtos, constitui desafio a ser enfrentado pela indústria, visando manter a aceitação e consumo dos derivados cárneos.

Broiler transportation conditions in a Brazilian commercial line and the occurrence of breast PSE (Pale, Soft, Exudative) meat and DFD-like (Dark, Firm, Dry) meat

The objective of this work was to investigate the effect of road transportation conditions on the occurrence of broiler PSE-(Pale, Soft, Exudative) and DFD-like (Dark, Firm, Dry) meats in the Brazilian commercial slaughterhouse plant. Samples of Pectoralis major m from 47-day-old broilers of commercial lineage were analyzed. The results indicated that water-bathing birds just before journey over 3.0km promoted the occurrence of 46.0 percent of PSE and 4.0 percent of DFD-like meat, while birds under non-water bathing conditions presented 14.7 and 2.0 percent, respectively. For a distance of 68.0km, the occurrences of PSE-and DFD-like meat were 44.0 and 0.0 percent under water bathing conditions, and 52.0 and 0.0 percent without water bathing, respectively. Water bathing at the farm was a critical manoeuvre for increasing the unfavourable truck microenvironment for short journey, whereas conversely for longer journey it was less stressful influencing the broiler breast meat quality.

O objetivo deste trabalho foi investigar o efeito das condições do transporte na ocorrência das carnes PSE (Pale, Soft, Exudative) e a-DFD (Dark, Firm, Dry) de frangos nas condições brasileiras em uma planta de um frigorífico comercial. Foram analisadas amostras de peito de frango (Pectoralis major m.) da ave de 47 dias de linhagem comercial. Os resultados indicaram que o banho dos frangos imediatamente antes da viagem de 3,0km promoveu a ocorrência de 46,0 por cento de PSE e 4,0 por cento de a-DFD enquanto que frangos sem banho apresentaram 14,7 e 2,0 por cento, respectivamente. Para uma distância de 68,0km, a ocorrência de carnes PSE e a-DFD foram 44,0 e 0,0 por cento, respectivamente, de aves que sofreram banho e 52,0 e 0,0 por cento sem banho, respectivamente. O banho ainda na granja foi uma atividade crítica aumentando as condições desfavoráveis no microambiente do caminhão para curtas distâncias e contrariamente para distâncias longas foi menos estressante influenciando na qualidade do peito do frango.

Lipid oxidation and fatty acid profile related to broiler breast meat color abnormalities

The aim of this work was to study the influence of lipid oxidation on broiler breast meat (Pectoralis major m) color abnormalities. There were 27.0 percent more lipid oxidation in PSE in relation to normal meat and 41.0 percent more in relation to DFD-like meat (p<0.05). The fatty acid profile was also significantly different since the arachidonic acid (AA) fraction increased 38.6 and 70.5 percent in PSE meat comparing to normal and DFD-like meats, respectively. The ratio PUFA/SFA changed in these three types of meat: 0.736, 0.713 and 0.694 for PSE, normal and DFD-like meat respectively, reflecting the highest production of polyunsaturated fatty acids in the PSE meat samples. Results indicated that phospholipase A2 enzyme activities played a relevant role towards the development of PSE-meat syndrome in a cascade of biochemical reactions promoting the formation of free radicals from AA, which ultimately damaged the muscle membrane systems.

A influência da oxidação lipídica no surgimento das anormalidades das cores do filé do peito de frango (Pectoralis major) foi avaliado. A oxidação lipídica foi 27 por cento maior em carnes PSE em relação ao normal e 41,0 por cento em relação ao análogo DFD (p< 0.05). O perfil dos ácidos graxos foi também significantemente diferente desde que a fração do ácido araquidônico (AA) aumentou 38,6 por cento e 70,5 por cento em carnes PSE em comparação às carnes normais e análogas ao DFD, respectivamente. A razão PUFA/SFA se alterou nos três tipos de carne, 0,736, 0,713 e 0,694 para carnes PSE, normal e análogo ao DFD, respectivamente, refletindo a maior produção dos ácidos graxos polinsaturados em amostras PSE. Esses resultados corroboram os nossos anteriores, indicando que a atividade da enzima fosfolipase A2 tem um papel relevante no desenvolvimento da síndrome do PSE em uma cascata de reações bioquímicas promovendo a formação dos compostos radicais livres do AA que finalmente compromete os sistemas das membranas celulares do músculo.

Quantitative differential expression of alpha and beta ryanodine receptor genes in PSE (Pale, Soft, Exudative) meat from two chicken lines: broiler and layer

Total RNA isolated from Pectoralis major muscle from PSE (L*24h>53.0, pH<5.8) and non-PSE (44<"L*24h>"53) meats of two phenotypically distinct chicken lines, broiler and layer, was used to investigate the α-ryr and β-ryr gene expression by real-time RT-PCR approach. Mean relative quantification (RQ) values were lower (p<0.05) for β-ryr in PSE chickens from both lines when compared to non-PSE chickens, while there was no difference (p>0.05) in α-ryr gene expression regardless of line studied. The β-ryr RQ results suggested that in PSE samples an alteration might occur in the regular ratio (1:1) of α-RyR/β-RyR normally found in avian muscles. These results provided the first evidence of PSE meat occurrence as a result of the differential expression of ryanodine receptor genes which might lead to an increased in Ca2+ availability at the cell milieu.

As proteínas α-RyR e β-RyR apresentam papéis distintos no mecanismo de excitação-contração com diferenças em seus mecanismos de ativação e respostas a ligantes. O RNA total de filé de peito (Pectoralis major m) com PSE (L*24h>53,0; pH 5,8) e não-PSE (44<"L*24h>53) de duas linhagens distintas, de corte e de postura, foram utilizadas para estudar a expressão gênica dos genes α-ryr β-ryr por PCR-em-tempo-real. Os valores médios de expressão gênicas relativas (RQ) foram inferiores (p<0,05) para em frangos PSE das duas linhagens quando comparadas aos frangos não-PSE. Por outro lado, não houve diferenças (p>0,05) na expressão do , independentemente da linhagem estudada. Os resultados de RQ para β-ryr indicaram nas amostras PSE, uma alteração na proporção (1:1) de α-RyR/β-RyR comumente encontrada em músculos de aves. Estes resultados originam a primeira evidência da ocorrência de carnes PSE como resultado de uma disponibilidade acentuada de Ca2+ no citosol pela expressão diferenciada de proteínas receptoras de rianodina.

Development of a gas chamber for detecting broiler chicken halothane sensitivity and PSE (Pale, Soft, Exudative) meat formation

The objective of this work was to investigate the use of a halothane to screen broiler chickens prone to develop PSE (Pale, Soft, Exudative) meat through a special gas chamber connected to a veterinarian anaesthetic apparatus developed in our laboratory. Anaesthesia was induced with approx. 3.0 percent halothane at a flow rate of 6.0 Lm-1 in pure oxygen for 5 min. Commercial male broilers (n=342) aged 46 days old were evaluated and classified as either halothane sensitive (HAL+) or insensitive (HAL-), depending on the leg rigidity response. Approximately 27.5 percent (n=94) of broilers were HAL+ and 72.5 percent (n=248) were HAL-. This is a simple and rapid technique to evaluate broiler sensitivity to halothane and identify broilers prone to develop PSE meat. The occurrence of PSE meat in HAL insensitive broiler chicken samples suggests that other factors are related to PSE occurrence.

O objetivo deste trabalho foi investigar o uso do halotano para avaliar e identificar frangos propensos ao desenvolvimento de carnes PSE (Pálida, Flácida, Exsudativa) por meio de uma câmara desenvolvida em nossos laboratórios. Esta foi conectada a um equipamento de anestesia veterinária e a anestesia foi então induzida com aproximadamente 3,0 por cento de halotano a um fluxo de 6,0 L/min em puro oxigênio. A sensibilidade de três frangos foi avaliada simultaneamente. Os frangos de linhagem comercial (n=352) com 46 dias de idade foram expostos à 3,0 por cento de halotano por 5 min e classificados como halotano sensível (HAL +) e não-sensível (HAL -), baseado no enrijecimento dos seus membros inferiores. Aproximadamente 27,5 por cento (n=94) frangos foram HAL+ e 72,5 por cento (n=248) HAL-. Amostras do músculo Pectoralis major (n=75) foram coletadas após o abate dos animais para as medidas de pH e cor, determinadas nos filés mantidos a 4 C por 24 h postmortem. Frangos HAL+ apresentaram maior porcentagem de carnes PSE quando comparadas ao grupo HAL-. Este é um teste simples e rápido para a avaliação da sensibilidade das aves ao halotano e identificar frangos propensos ao desenvolvimento de carnes PSE embora amostras de HAL - também apresentaram carnes PSE sugerindo que outros fatores estão relacionados com a formação da anormalidade.

Vehicle thermal microclimate evaluation during Brazilian summer broiler transport and the occurrence of PSE (Pale, Soft, Exudative) meat

The formation of a thermal microclimate within the vehicle during the transport of broilers from farm to slaughterhouse affects the birds' welfare and potentially promotes the development of PSE meat. Thus, the aim of this work was to evaluate the effects of routine commercial practices on the vehicle microclimate formed during transportation of broilers. Twenty-four hours postmortem Pectoralis major m. samples were classified as PSE meat by determining pH and color (L*, a* e b*). Results showed that broiler located at the rear of the truck and with longer journey presented higher amounts of PSE meat because birds were under harsh conditions of both temperature and relative humidity. The ventilation decreased gradually from the front to the rear of the truck, and the water bath at the farm was beneficial over a long distance by reducing the overall occurrence of PSE meat.

O microambiente térmico formado no caminhão de transporte de frangos da granja ao abatedouro pode ser a causa primária que compromete o bem estar das aves e a qualidade final da carne com o desenvolvimento de PSE (Pale, Soft, Exudative) em filés de peito de frango. O objetivo deste trabalho foi avaliar o efeito do microambiente formado durante o transporte por caminhão em uma linha comercial. Para classificação de filés de peito em PSE, o pH e a cor (L*, a* e b*) foram medidos nos filés de peito de frango 24 h postmortem. Os resultados mostraram que em jornadas longas, as aves transportadas nas regiões do meio e fundo do veículo apresentaram maior ocorrência de PSE devido às drámaticas condições de temperatura e umidade relativa no microambiente destas regiões. A ventilação diminuiu gradualmente da frente à trazeira do caminhão e a aplicação do banho de água sobre os frangos após o carregamento na granja foi benéfica em jornadas longas ao reduzir a ocorrência de carnes PSE.

The effect of management of transport and lairage conditions on broiler chicken breast meat quality and DOA (Death on Arrival)

The aim of this work was to evaluate the influence of time of broiler chicken transportation and lairage prior to slaughtering on the occurrence of PSE (Pale, Soft, Exudative) meat and Death On Arrival (DOA) under non-commercial conditions in the Brazilian summer. Male birds (n=250) from a commercial line were subjected to different periods of journey (30, 90, and 180 min) and lairage (0, 90, and 180 min) before slaughtering. The occurrence of PSE was higher in broilers subjected to shorter journeys and lairage periods, whereas DOA was more pronounced upon longer periods of transport and lairage. The DOA occurrence percentage was much higher in comparison to commercially available figures, confirming that broiler chickens are very sensitive to both transport and lairage maneuvers.

O objetivo desse trabalho foi avaliar a influência do tempo de transporte e período de descanso antes do abate dos frangos na ocorrência das carnes PSE (Pale, Soft, Exudative: Pálido, Amolecido e Exsudativo) e DOA (Dead On Arrival: Morte Na Chegada) nas condições não comerciais durante o verão brasileiro. Frangos machos (n=250) de uma linhagem comercial foram submetidos a diferentes periodos de jornada (30, 90 e 180 min) e descanso (0, 90 e 180 min) antes do abate. A ocorrência do PSE foi maior em frangos submetidos tanto em tempos para as viagens curtas como para o de descanso enquanto que DOA foi mais pronunciada em condições de jornadas longas e maior periodo de descanso. A porcentagem da ocorrência do DOA foi maior ao se comparar com os resultados obtidas por empresas comerciais confirmando que os frangos são sensiveis às condições das viagens e de descanso a que são submetidos.

Functional properties of PSE (Pale, Soft, Exudative) broiler meat in the production of mortadella

This work was carried out in order to evaluate whether the functional properties of broiler meat are affected by the factors that lead to PSE (Pale, Soft, Exudative). PSE meat was characterized by pH and L* values, and mortadella formulations consisted of isolated soy protein, sodium tripolyphosphate, and cassava starch in addition to PSE and normal meats. The functionality of the meat was evaluated by examining the water holding capacity (WHC), texture profile, emulsion stability (ES) and color of the final products. The results show that in mortadella prepared with PSE meat, the protein denaturation affected the ES. Additives are necessary to enhance the functional properties of PSE meat.

Este trabalho foi realizado para avaliar o efeito dos fatores que conduzem à formação das carnes PSE (Pale, Soft, Exudative) sobre as propriedades funcionais da carne de frango. Carnes PSE foram caracterizadas pelos valores de pH e L* e as formulações da mortadela consistiram de proteina isolada de soja, trifosfato de sódio, amido de mandioca e a adição das carnes normal e PSE. A funcionalidade da carne foi avaliada medindo a capacidade de retenção de água (CRA), perfil de textura, estabilidade de emulsão (EE), e cor dos produtos finais. Os resultados mostraram que na mortadela preparada com carnes PSE, as proteinas desnaturadas afetaram a EE. Aditivos são necessários para potencializar as propriedades funcionais da carne PSE.

Sensitivity to halothane and its relationship to the development of PSE (Pale, Soft, Exudative) meat in female lineage broilers

This work aimed to evaluate female lineage broilers for halothane sensitivity and for their susceptibility to the subsequent development of PSE meat. The halothane test was carried out in an anesthetic chamber with 3.0 percent halothane. The unconscious birds were examined for leg muscle rigidity. If one or both legs became extended and rigid, the birds were classified as halothane sensitive (HAL+), while unresponsive birds were classified as halothane negative (HAL-). The results showed that of 298 birds aged 42 days old, 95.6 percent were HAL- and 4.4 percent were HAL+. A sample of pectoralis major muscle was collected from HAL- (n=105) and HAL+ (n=13) birds. The pH and breast fillet color were determined at 4ºC, 24 hours post-mortem. Interestingly, only 2.5 percent of HAL+ birds displayed PSE meat characteristics compared to 12.7 percent of HAL- individuals. The halothane test demonstrated that female lineage broilers displayed very little sensitivity towards halothane, indicating that the development of PSE meat is related to other environmental factors.

O objetivo deste trabalho foi avaliar a sensibilidade de aves de uma linhagem fêmea ao halotano e sua relação com o desenvolvimento de carnes PSE. O teste do halotano foi conduzido com o auxílio de uma câmara anestésica com 3,0 por cento de halotano volatilizado. As aves inconscientes foram examinadas pelo enrijecimento dos seus membros inferiores. Quando ambos ou um dos membros permaneceram rígidos, os frangos foram classificados como sensíveis ao halotano (HAL+) e os frangos sem enrijecimento dos membros foram classificados como não-sensíveis (HAL-). Os resultados mostraram que de 298 frangos com 42 dias de idade, 95,6 por cento foram HAL-, e apenas 4,4 por cento HAL+. O peito foi coletado das aves HAL- (n=105) e HAL+ (n=13) em que o pH e Cor (L*,a*,b*) foram determinados a 4ºC, 24h postmortem. Interessantemente, apenas 2,5 por cento das aves HAL+ demonstraram carnes PSE, enquanto que as aves HAL- apresentaram 12,7 por cento de carnes PSE, em relação ao total de aves abatidas. O teste do halotano demonstrou que frangos da linhagem fêmea mostraram pouquíssima sensibilidade ao halotano, indicando que a ocorrência de carnes PSE está mais associada a fatores ambientais.

Molecular cloning of α RYR hotspot region 1 from broiler chicken

Samples of Pectoralis major m. were collected, and an RT-PCR analysis of the a-Ryanodine receptor (a RYR) from chicken mRNA hotspot region spanning aminoacid residues 386 to 540, numbered according to the turkey sequence, revealed two classes of transcripts. The sequences of the first class were similar to turkey and human with 97 percent and 74 percent of identity, respectively, and included all transcripts with substitutions in the nucleotide sequence. The second class was characterized by the deletion of nucleotides, leading to a premature stop codon and coding for a truncated and nonfunctional protein. These results are to date the first report related to the sequencing of the chicken αRYR hotspot region 1, which will possibility serve as a guide for further studies regarding a solution in the poultry production chain related to the problem of pale, soft and exudative (PSE) meat.

Amostras do músculo Pectoralis major foram coletadas e uma RT-PCR foi conduzida para avaliar a sequência do mRNA do αRYR, região compreendida entre os resíduos de aminoácido 386-540, numerado de acordo com a sequência de perus. Os resultados revelaram duas classes de transcritos. O primeiro teve 97 por cento e 74 por cento de identidade com as sequências de αRyR e RyR1 de perus e humanos, respectivamente, e incluiu todos os transcritos com substituições de nucleotídeos. A segunda classe de transcritos foi caracterizada pela deleção de bases que levaram a um stop códon prematuro e a uma proteína truncada não-funcional. Esses resultados são até o momento, o primeiro relato de sequenciamento do αRYR, região hotspot1 de frangos e podem servir como guia para estudos futuros na tentativa de se encontrar uma solução para os problemas na cadeia de produção de frangos relacionados com as carnes PSE (pálida, flácida e exsudativa).

Comparison of proximate chemical composition and texture of cupim, Rhomboideus m. and lombo, Longissimus dorsi m. of Nelore (Bos indicus)

The proximate chemical composition of hump, known in Brazil as cupim, Rhomboideus m. (RB), of Nelore (Bos indicus) aged 24 months revealed it to be a unique beef muscle. It presents a lipid fraction 14-fold as high as that of Longissimus dorsi m. (LD) taken from the same animal (p<0.05), the highest value reported so far. This was unequivocally observed by the histological evaluation. Proportionally more protein fraction and conversely less moisture were also observed in RB. Analysis of collagen and its crosslinking with hydroxylysylpyridinium (HP) showed there to be 22.9 percent more collagen and 14-fold as much HP in RB as in LD. Contrary to the expectations, the tenderness of fresh samples evaluated by Warner Bratzler shear force measurements led to values of 8.05 and 5.81 kgf for LD and RB, respectively (p<0.05). These results showed that the abundant fat in fresh RB acted as a lubricant for the needle penetration, irrespective of the quantity and quality of collagen fibres present.

A composição química percentual aproximada do cupim m. Rhomboideus (RB) derivado de Nelore (Bos indicus) de 24 meses de idade mostrou ser um músculo diferenciado. Há uma maior fração de material lipídico em RB chegando a ser 14 vezes proporcionalmente maior em comparação ao m. Longissimus dorsi (LD) (p<0,05) a maior quantidade de gordura relatada em amostras de carne em literatura científica. Esse fato foi também observado pela avaliação histológica. Há proporcionalmente maior concentração da fração protéica e menor quantidade de umidade em RB. O teor de colágeno foi de 22,9 por cento mais concentrado em RB enquanto que a quantidade da sua ligação cruzada, hidroxilisilpiridinolina (HP) foi 14 vezes maior indicando que cupim seria mais rígido. Contrariando essa expectativa, a maciez da carne crua avaliada pelo texturômetro mostrou valores de 8.05 e 5.81 kg/F para LD e RB, respectivamente (p<0.05). Tais resultados mostram que em músculo contendo abundante gordura esta funciona como lubrificante para a lamina penetrar sem muita resistência através do cupim a despeito dar quantidade e qualidade das fibras de colágeno.

Chemical basis for beef charqui meat texture

This work evaluated the relationship of charqui meat (CHM) chemical composition with the tenderness throughout its production. CHM was prepared from beef Vastus lateralis of 4-5 years old. Shear force of fresh CHM showed an approx. 3-fold increase in toughness compared to the raw material while, in the case of cooked CHM it was 6-fold increased in relation to the raw charqui. The moisture content decreased by 39.0 and 58.0 percent (p<0.05) for uncooked and cooked CHM, respectively, in relation to the raw material. Mathematical modeling of the influence of these meat components showed that shear force increased exponentially with the loss of moisture. The texture of CHM was the result of a multitude of factors involving myofibril proteins which promoted dynamic biochemical events such as the binding of water molecules. It was the amount of the latter which ultimately determine the final charqui meat texture.

Este trabalho avaliou a relação entre a composição química aproximada do charque (CHM) com a maciez durante todas as etapas de sua produção. CHM foi produzida do m. Vastus lateralis bovino (patinho) de aproximadamente 4-5 anos de idade. A força de cisalhamento do charque cru mostrou o valor aproximado de 3 vezes maior em dureza comparada à matéria prima enquanto que no caso do CHM cozido houve 6 vezes maior em aumento sob as mesmas condições.O índice de umidade diminui de 39 a 58 por cento (p<0,05) para CHM cru e cozido, respectivamente, em relação à matéria prima. O modelo matemático da influência destes componentes mostrou que a força de cisalhamento aumentou exponencialmente com a perda de umidade. A textura do charque é o resultado da associação de multifatores envolvendo proteínas miofibrilares que provocam eventos bioquímicos dinâmicos como a sua ligação com as moléculas da água. É a quantidade destas que determina a textura final do charque.

Uso de regressão linear para estimar parâmetros físico-químicos relacionados à qualidade do jerked beef / Use of linear regression to estimate physicochemical parameters associated to jerked beef quality

O jerked beef é oficialmente descrito como carne bovina salgada, curada e dessecada. Os parâmetros físico-químicos utilizados na determinação do seu padrão oficial de identidade e qualidade são a atividade de água e os teores de umidade, matéria mineral (ou cinzas) e nitrito residual. Neste trabalho, foi avaliada a evolução desses parâmetros durante o processamento do produto. Verificou-se haver uma correlação significativa entre eles, o que permitiu estabelecer equações estatísticas, que possibilitam estimar todos esses parâmetros através da aferição de apenas um deles.

Jerked beef is officially defined as salted, cured and dried beef. Water activity (Aw), moisture, ash and residual nitrite are the physicochemical parameters that define this product identity and quality standards. In this work, the behavior of these parameters during jerked beef processing was evaluated and a significant correlation among them was revealed. These results allowed the establishment of statistical equations that enable the estimation of all the physicochemical parameters from the results obtained in the measurement of just one of them.