Evaluation of attributes that affect longissimus muscle tenderness in Bos taurus and Bos indicus cattle.

Abstract

Biological tenderness differences between longissimus muscles (LM) from Bos indicus and Bos taurus breeds were evaluated. Steers and heifers of Hereford x Angus (H x A, n = 10), 3/8 Sahiwal x H, A or H x A (3/8 SAH, n = 6) and 5/8 Sahiwal x H, A or H x A (5/8 SAH, n = 11) crosses were utilized. Muscle temperature and pH were monitored every 3 h for the first 12 h and at 24 h. Samples were obtained within 1 h and at 24 h postmortem from the LM for determination of calcium-dependent protease (CDP) -I and -II and CDP inhibitor (INH) activities. At 1 and 14 d postmortem, LM samples were removed for determining cathepsin B and B + L activity, soluble and total collagen, sarcomere length, muscle-fiber histochemistry, shear force and sensory-panel traits. Data were analyzed using least squares procedures with fixed effects of breed cross, sex and their interaction. No significant breed cross effects were observed for carcass traits or rates of pH and temperature decline. Steaks from H x A had lower (P less than .05) shear-force values and higher (P less than .05) sensory scores for tenderness at 1 and 14 d postmortem than steaks from 3/8 and 5/8 SAH. Correspondingly, 5/8 SAH had lower (P less than .05) myofibril fragmentation indices than H x A at 1, 3, 7 and 14 d postmortem. Breed cross effects were not significant for sarcomere length, fiber types, soluble and total collagen, cathepsin B and B + L specific activity, CDP-I and -II activity and INH activity within 1 h postmortem. However, INH total activity/100 g of muscle was greater (P less than .01) at 24 h postmortem for 5/8 SAH (208.8 +/- 14.8) and 3/8 SAH (195.6 +/- 19.3) than for H x A (136.3 +/- 14.9). For H x A, SDS-PAGE revealed that by d 1 desmin had been subjected to proteolysis, and by d 14 desmin could not be detected, but a 30,000-dalton component was clearly evident. However, in 5/8 SAH, desmin remained visible at d 14 without a 30,000-dalton component appearing. This reduced protein hydrolysis may account for less tender meat in SAH; INH apparently influences this process.

Impacto do pH final na maciez do músculo <i>Longissimus lumborum </i>de animais zebuínos: mudanças estruturais de proteínas da carne crua e cozida durante a maturação

“…Independente da temperatura interna de cozimento, os valores de força de cisalhamento foram altos em quase todos os dias post mortem para ambas as faixas de pHf, o que sugere a necessidade de utilizar métodos físicos ou químicos para aumentar a maciez do músculo Longissimus lumborum de animais zebuínos. (SHACKELFORD et al, 1991;WHEELER et al, 1990;WHIPPLE et al, 1990). Isto representa um desafio para a indústria de carnes brasileira, considerando que a maciez é o atributo de qualidade mais importante por ser avaliado durante a mastigação.…”

“…Segundo Promeyrat et al (2010b), o processo de agregação pode estar envolvido nas mudanças estruturais das miofibrilas durante o cozimento, fato que poderia explicar as mudanças na estrutura das fibras com o aumento da temperatura observados no presente trabalho. (SHACKELFORD et al, 1991;WHEELER et al, 1990;WHIPPLE et al, 1990).…”

“…Como exemplo podemos citar a desmina e a troponina T, que são degradadas durante o período de maturação da carne em refrigeração (HUFF-LONERGAN et al, 1996;TAYLOR et al, 1995;WHIPPLE et al, 1990 (CONTRERAS-CASTILLO et al, 2016;LOMIWES et al, 2013;PULFORD et al, 2009PULFORD et al, , 2008PURCHAS;YAN;HARTLEY, 1999;TONG;GIBSON, 1991).…”

“…A desnaturação térmica das proteínas tem sido amplamente estudada por calorimetria exploratória diferencial (differential scanning calorimetry, DSC). As proteínas miosina, actina e colágeno contribuem com os parâmetros de textura da carne, e a desnaturação térmica delas pode ser afetada pelo pH (BERTAZZON; TSONG, 1990;MARTENS, 1980;WILDING, 1984;LEACH;WILDING, 1977) (SHACKELFORD et al, 1991;WHEELER et al, 1990;WHIPPLE et al, 1990 (TAYLOR et al, 1995).…”

“…A degradação da desmina e troponina T é um excelente indicador do amaciamento do músculo post mortem (HUFF-LONERGAN et al, 1996;TAYLOR et al, 1995;WHIPPLE et al, 1990). Tem sido reportado que a desmina produz três produtos de degradação, com pesos moleculares de 45.000, 38.000 e 35.000 Da, sendo que o maior produto de degradação é o polipeptídio de 38.000 Da (HUFF-LONERGAN et al, 1996).…”