Turkey carcass chilling and protein denaturation in the development of pale, soft, and exudative meat.

Pale, soft, and exudative (PSE) meat is a growing problem in the turkey industry and has been associated with processing conditions such as slow carcass chilling. The development of PSE meat is caused by protein denaturation resulting from a rapid rate of pH decline early postmortem (PM) while carcass temperatures are still elevated. This research was conducted to determine the relationship of slow chilling to protein denaturation and PSE development. A total of 48 toms were conventionally processed in 2 trials at 22.5 wk of age, and chilled at 0, 10, 20, or 30 degrees C for either 45 or 90 min before deboning (at 60 or 105 min PM). Temperature and pH of the breast muscle was recorded at 15 min PM, at the time of deboning (60 or 90 min PM), and at 24 h PM. Color was determined at deboning and again at 24 h PM. Gel strength, cook loss, expressible moisture, total protein solubility, and bound phosphorylase quantities were determined on the fillets at 24 h PM. There was no difference in carcass temperature at 15 min PM, but by 105 min PM each temperature treatment was significantly different, with the carcasses chilled at 0 and 10 degrees C having the lowest temperature, the 30 degrees C-chilled birds having the highest temperature, and the 20 degrees C-chilled carcasses being intermediate but significantly different from either extreme. The carcass temperature differences at 105 min PM indicated that the carcass experienced differing chilling rates. To varying degrees, slower rates of chilling resulted in lower pH, greater degree of lightness (L* value), greater cook loss, and reduced gel strength. However, chilling rate had no effect on total protein solubility or myofibrillar phosphorylase for any of the treatments. Chilling rate seems to contribute to PSE turkey meat characteristics but by a mechanism independent of total protein solubility or myofibrillar phosphorylase.