|Van Laack, Riette|
Submitted to: Journal of Muscle Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 24, 1997
Publication Date: N/A
Interpretive Summary: Poultry, like pigs, have been subjected to intense genetic selection for rapid lean muscle growth. The selection traits used are most often related to economic importance rather than any scientific (biophysical or biochemical) significance. Unfortunately, selection for maximal lean tissue growth appears to be associated with increased stress susceptibility (e.g., ,porcine stress syndrome) and/or myopathic conditions. In pigs, the incidence of pale, soft, exudative (PSE) muscle has been shown to be related to muscle size, stressful preslaughter handling conditions and an accelerated post-mortem metabolic rate. These negative attributes have been shown to be a result of stress sensitivity of the live animal. Relatively little information is available on poultry. The existence of PSE condition in poultry, particularly in turkeys, has not been well defined. Often, the term 'atypical poultry meat' is used and whether or not this term defines poultry PSE meat to be similar to PSE in pork is uncertain. This paper reviews the biophysical aspects of pig and poultry muscle. Similarities, differences, and abnormalities and relationships to meat quality are discussed.
Technical Abstract: Problems in meat quality are usually caused by aberrations in the biochemistry and morphology of individual muscles, as well as by post- mortem events. Poultry, like pigs, have been subjected to intense genetic selection for rapid lean muscle growth. The selection traits are most often associated with economic importance rather than biophysical significance, which often results in stress syndromes (e.g., porcine stress syndrome). These conditions often give rise to pale, soft, exudative (PSE) muscle. The occurrence of PSE muscle and subsequent alterations in meat quality have been shown to be related to increases in muscle size, stressful preslaughter handling conditions, and/or onset of rigor mortis. Morphological studies of myofiber types from stress-susceptible animals have yielded contradictory and confusing data, although a trend toward increases in fast-twitch fibers is evident. Histological studies have revealed significant increases in fiber size, in addition to structural irregularities. These structural irregularities include decreased capillary density, hypercontracted (giant) fibers, and myoplasmic calcium loading. The common theme between poultry and swine in the development of PSE muscle is predominately in anaerobic fast-twitch muscles with low energy lactate metabolism yet accelerated onset of rigor mortis.