Protease activity and the ultrastructure of broiler chicken PSE (pale, soft, exudative) meat

Abstract

a b s t r a c tThe biological cause of broiler PSE meat seems to be an excessive release of Ca 2+ , promoted by a genetic mutation of ryanodine receptors located in the sarcoplasmic reticulum of skeletal muscle cells. Excessive Ca 2+ , associated with protein denaturation in meat, enhances protease activity and influences the functional properties of PSE meat. Twenty-four-hour post-mortem Pectoralis major m. samples exhibited lower values for pH, water-holding capacity, and shear force than did control samples, in contrast to colour (L * ) and cooking loss values. Protease activity, measured as myofibril fragmentation index, presented higher values in PSE meat than in control samples. Ultrastructural examination revealed shrinking and depolymerisation of myofilaments and Z-lines disorganisation within the sarcomere in PSE meat. Intense calpain activity was also observed, indicating that the process may initiate at the filaments, because of protein denaturation, and spread through Z-lines, resulting in the collapse of the sarcomere structure.

Breast meat quality of chickens with divergent growth rates and its relation to growth curve parameters

“…However, the growth potential of the broilers, given as BW A , had a favorable association with cooking loss and the expressible moisture of breast meat, indicating that even in fast-growing strains, simultaneous improvements in water retention and growth performance are not precluded but can be achieved by increasing the growth potential rather than the growth speed. A rapid pH fall and high temperatures during the early post-mortem phase can trigger myofiber shrinkage and impair protein functionality, leading to reduced water retention of muscles (Wilhelm et al, 2010). When the reduction in water-holding capacity is associated with pale color and low ultimate pH, the resulting meat could be referred to as PSE-like meat (Woelfel et al, 2002;Wilhelm et al, 2010).…”

“…A rapid pH fall and high temperatures during the early post-mortem phase can trigger myofiber shrinkage and impair protein functionality, leading to reduced water retention of muscles (Wilhelm et al, 2010). When the reduction in water-holding capacity is associated with pale color and low ultimate pH, the resulting meat could be referred to as PSE-like meat (Woelfel et al, 2002;Wilhelm et al, 2010). However, cooking losses of commercial broilers slaughtered at 7 and 10 weeks of age were increased compared to 4-week-old broilers, despite high ultimate pH values.…”

“…Meat quality defects, which have been linked to selection on growth rate and breast muscle development in chickens, are, for instance, the pale, soft, exudative (PSE)-like and dark, firm, dry (DFD)-like meat conditions, white striping of breast meat, and "wooden" breast condition (Petracci et al, 2009;Kuttappan et al, 2012;Petracci et al, 2013;Kralik et al, 2014;Mudalal et al, 2015). These quality aberrations are associated with altered functional properties of meat, which, depending on the respective defect, can affect pH, color, water-holding capacity, and tenderness of raw and/or cooked meat (Woelfel et al, 2002;Wilhelm et al, 2010;Petracci et al, 2013;Mudalal et al, 2015). However, it was also suggested that, although intense selection on growth performance and breast yield elicited differences in muscle tissue histology and metabolism, there is little evidence of adverse effects on meat quality in chickens besides slight modifications in color (Rémignon and Le Bihan Duval, 2003;Duclos et al, 2007).…”

Meat quality and performance of pigs fed diets with fish silage meal

“…The loin and fat depths were used to calculate the lean meat content according to Guidoni (2000), and the percentage of lean meat was obtained as in Bridi & Silva (2009). Loin samples of approximately 400 g were taken to determine water retention capacity (Wilhelm et al, 2010), color, pH, cooking loss, and shear force of meat (Caldara et al, 2012).…”

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

“…pH values less than 5.8 and L 24 h * values higher than 53.0 were classified as PSE, and pH values higher than 5.8 and L 24 h * between 44.0 and 53.0 were classified as normal (Kissel et al 2009;Wilhelm et al 2010).…”