Perdas de água em carcaças de suíno
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2018-05-11
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A produção de carne suína no atual contexto socioeconómico é um desafio multifatorial, constituído por diversas etapas de elevada sensibilidade. A refrigeração de carcaças representa uma dessas etapas, com elevado impacto não só na rentabilidade do negócio como na qualidade do produto. A sua influência em parâmetros de qualidade da carne está relacionada sobretudo com a taxa de arrefecimento. As primeiras 24 horas são cruciais sobretudo numa espécie como a suína, onde encontramos elevadas temperaturas musculares juntamente com baixos níveis de pH nas primeiras horas post mortem. Este binómio temperatura alta – pH baixo pode ter consequências nefastas, nomeadamente através da desnaturação proteica a nível múscular, que tem implicação direta na capacidade da carne em reter água e consequentemente em carateristicas como a tenrura, o sabor e o aspeto da mesma. O foco deste estudo incidiu sobre o sistema de refrigeração integrado no matadouro da empresa que nos propôs avaliar as condições de refrigeração, estudar as perdas de peso das carcaças resultantes desta e alguns parâmetros ante e post mortem que poderão influenciar a rentabilidade do processo. A avaliação do sistema de refrigeração e da sua capacidade foi realizada pela análise da evolução das temperaturas dos túneis e das câmaras ao longo da passagem das carcaças de teste, e ainda, pela determinação do tempo até se atingir 7ºC no interior da perna, através do uso de sondas de temperatura. Foram ainda registadas as variações de humidade relativa de cada câmara, parâmetro que merece também destaque no sentido de avaliar as causas para as perdas em água. A avaliação das perdas em água nas carcaças estudadas foi feita pela comparação dos pesos logo após o abate (30’ pm) e às 24 h post mortem. Para avaliar alguns parâmetros de qualidade da carne foi determinado o pH (aos 30’ pm e às 24h pm) e realizado o teste gravimétrico de Honikel para determinação da capacidade de retenção de água (CRA). Para além destes parâmetros que constituem o cerne deste estudo, foram ainda avaliados alguns fatores que se podem relacionar e produzir um impacto nas quebras de peso ou na qualidade da carne como: os tempos de viagem, de espera e de abegoaria e o tempo de jejum (com pesagem do trato gastrointestinal e mensuração da vesicula biliar na tentativa de encontrar um indicador de fácil leitura para os tempos de jejum na linha de abate)Os resultados revelaram alguns problemas a nível da capacidade do primeiro e segundo choques térmicos (primeiras 2h 15 minutos post mortem), que não conseguem manter uma eficácia constante ao longo do dia de trabalho na remoção de calor das carcaças, numa fase em que o desacelerar das reações bioquímicas a nível muscular é imperativo. Tudo isto se traduziu em perdas elevadas, de forma proporcional à hora de entrada no circuito de refrigeração (Carcaças a meio da manhã apresentaram menor rendimento de carcaça face às carcaças do inicio da manhã, assim como carcaças do final da manhã apresentaram menor rendimento de carcaça quando comparadas com carcaças do meio da manhã). A incidência de carcaças com condição PSE (Pale, Soft and Exsudative) não foi significativa (1,36%), bem como de carcaças com condição DFD (Dark, Firm and Dry) – 3,18%. A elevada disparidade entre os pesos das carcaças contribuiu também para uma falta de uniformização dos lotes, e consequentemente das características do seu arrefecimento. Os animais sofrem ainda tempos de espera (entre a carga e o abate) elevados, que, juntamente com o jejum de exploração, pode aumentar os níveis de stress crónico derivado da fome com potenciais perdas de peso. Concluiu-se então que uma uniformização dos lotes, a par de uma reestruturação a nível dos dois primeiros choques térmicos e da câmara de refrigeração poderão aumentar os níveis de rentabilidade através da redução das perdas por enxugo. Adicionalmente, um maior controlo e rigor relativamente aos tempos de espera e maneio do stresse dos animais poderá ser uma mais valia, também no sentido de reduzir potenciais fatores desestabilizadores.
Pork production nowadays represents a true challenge in the socioeconomical context that we live in, and its many steps are highly sensitive. Carcass refrigeration is one of them. A key step, which can cause high impact on the final product quality and on business profitability. This process step can affect meat quality traits, mainly through the cooling rate of the carcasses. The first 24 hours post mortem (pm) are crucial, even more when we are dealing with a highly sensitive species like pigs. Pigs, due to many stressor factors, exhibit high body temperatures and low muscular pH levels on the first pm hours. This high temperature – low pH binomial can bring some negative consequences, causing a significant increase in protein denaturation, which is going to dramatically decrease meat’s water holding capacity, affecting some main quality traits as tenderness, flavor and its visual appearance. The focus of the present study was over the refrigeration system of the slaughterhouse which allowed us to develop this work. They proposed us to evaluate the refrigeration conditions, analyse the weight losses and some ante mortem and post mortem parameters which can directly influence the process’s yield. The evaluation of the refrigeration system and its performance was carried out by analyzing the temperature evolution from the tunnels and from the final refrigeration chamber, during the time the marked carcasses are submitted to this circuit. Using dataloggers within the deep leg muscles, we were able to determine how much time each carcass took to reach an internal temperature of 7ºC aswell. We recorded the relative humidity values along the time each studying carcass went through each step of the process, because relative humidity can also contribute to rise the weight losses by promoting evaporation. The carcasses water losses were evaluated by comparing carcass weights 30 minutes after slaughter (30’ pm) and 24 hours later. Some main meat quality traits were determined like pH at 30 minutes pm and at 24 hours pm. The Driploss test (Honikel, 1989), was performed to evaluate the water holding capacity of each carcass. In addition to these main parameters, we studied some factors which may relate to those mentioned above and cause impact on weight losses or in meat quality traits like: travel time to the slaughterhouse, lairage time and fasting time (with weighing of the gastrointestinal tract and measuring each gallbladder, trying to find some easy reading indicator of the fasting time on the slaughter line). Results revealed some flaws in the cooling capacity of the two tunnels (2 first thermal shocks), which cannot maintain a constant performance through each day. In this phase slowing down the muscular biochemical reactions is key to obtains good results. These findings translated in growing losses as the time of entering the refrigeration circuit goes on each day (Mid-morning carcasses presented lower carcass yield compared to early morning carcasses, as late morning carcasses presented lower carcass yield when compared to mid-morning carcasses). The incidence of PSE carcasses (Pale, Soft and Exsudative) wasn’t significative (just 1,36%), as the incidence of DFD carcasses (Dark, Firm and Dry) with just 3,18%. The huge heterogeneity of the carcass weights also contributed to a non-uniform cooling pattern. The animals are submitted to large travel and lairage times, which, in addition to the fasting time on farm can increase the chronic stress levels due to hunger and potentialize weight losses. We can conclude that an uniformization of the batches, together with a plan to restructure the two first thermal shocks (Tunnel 1 and Tunnel 2) and the final refrigeration chamber may increase the profitability levels, by reducing the water losses on this critical step of the process. Aditionally, it may be beneficial a to have a more rigorous control over lairage times and animal handling, which can promote the process yield by increasing animal welfare patterns.
Pork production nowadays represents a true challenge in the socioeconomical context that we live in, and its many steps are highly sensitive. Carcass refrigeration is one of them. A key step, which can cause high impact on the final product quality and on business profitability. This process step can affect meat quality traits, mainly through the cooling rate of the carcasses. The first 24 hours post mortem (pm) are crucial, even more when we are dealing with a highly sensitive species like pigs. Pigs, due to many stressor factors, exhibit high body temperatures and low muscular pH levels on the first pm hours. This high temperature – low pH binomial can bring some negative consequences, causing a significant increase in protein denaturation, which is going to dramatically decrease meat’s water holding capacity, affecting some main quality traits as tenderness, flavor and its visual appearance. The focus of the present study was over the refrigeration system of the slaughterhouse which allowed us to develop this work. They proposed us to evaluate the refrigeration conditions, analyse the weight losses and some ante mortem and post mortem parameters which can directly influence the process’s yield. The evaluation of the refrigeration system and its performance was carried out by analyzing the temperature evolution from the tunnels and from the final refrigeration chamber, during the time the marked carcasses are submitted to this circuit. Using dataloggers within the deep leg muscles, we were able to determine how much time each carcass took to reach an internal temperature of 7ºC aswell. We recorded the relative humidity values along the time each studying carcass went through each step of the process, because relative humidity can also contribute to rise the weight losses by promoting evaporation. The carcasses water losses were evaluated by comparing carcass weights 30 minutes after slaughter (30’ pm) and 24 hours later. Some main meat quality traits were determined like pH at 30 minutes pm and at 24 hours pm. The Driploss test (Honikel, 1989), was performed to evaluate the water holding capacity of each carcass. In addition to these main parameters, we studied some factors which may relate to those mentioned above and cause impact on weight losses or in meat quality traits like: travel time to the slaughterhouse, lairage time and fasting time (with weighing of the gastrointestinal tract and measuring each gallbladder, trying to find some easy reading indicator of the fasting time on the slaughter line). Results revealed some flaws in the cooling capacity of the two tunnels (2 first thermal shocks), which cannot maintain a constant performance through each day. In this phase slowing down the muscular biochemical reactions is key to obtains good results. These findings translated in growing losses as the time of entering the refrigeration circuit goes on each day (Mid-morning carcasses presented lower carcass yield compared to early morning carcasses, as late morning carcasses presented lower carcass yield when compared to mid-morning carcasses). The incidence of PSE carcasses (Pale, Soft and Exsudative) wasn’t significative (just 1,36%), as the incidence of DFD carcasses (Dark, Firm and Dry) with just 3,18%. The huge heterogeneity of the carcass weights also contributed to a non-uniform cooling pattern. The animals are submitted to large travel and lairage times, which, in addition to the fasting time on farm can increase the chronic stress levels due to hunger and potentialize weight losses. We can conclude that an uniformization of the batches, together with a plan to restructure the two first thermal shocks (Tunnel 1 and Tunnel 2) and the final refrigeration chamber may increase the profitability levels, by reducing the water losses on this critical step of the process. Aditionally, it may be beneficial a to have a more rigorous control over lairage times and animal handling, which can promote the process yield by increasing animal welfare patterns.
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Carne suína , Refrigeração de carcaças , Qualidade da carne , Capacidade de retenção de água , Carnes PSE , Carnes DFD