Effects Of Heat Stress And Scalding And Cooling Process On Broiler Meat Quality And The Mechanism

Recent years, the chicken industry develops rapidly. Chicken with high protein and relatively lower fat content is favored by many Japanese and Western consumers. With the growing consumption of chicken meat, the edible quality and processing characteristics has been key issues consumers care most. Factors affecting the quality of chicken mainly include genetic factors, management before slaughter and slaughter process. Acute heat stress may bring adverse effect on meat quality. Many scholars have carried out relevant report. But now the mechanism of heat stress is still with a fierce controversy. Scalding and cooling process can affect meat quality, but there is few report on its mechanism and its effect on acute heat stress.The purpose of this experiment is to study effects of different slaughter processes and acute heat stress on meat quality and their mechanism. AA broilers were selected as the experimental material. Two groups of broilers were subjected in temperature of 36?(1h, HS) and control temperature of 14?(1h, CK), respectively. Then broilers were processed in simulating commercial conditions and laboratory slaughter process. Routine meat quality indicators such as pH, color, and water holding capacity, potential of glycolysis post-mortem, activity of metabolic enzyme were determined to analysis the effect slaughtering process on meat quality, and the mechanism of heat stress were explored through both glycolysis post-mortem and oxidative injury pathways. The main results of this study are as follows:(1)The breast surface brightness early post-mortem was improved by scalding and cooling process, however, the experimental scalding parameter did not significantly affected the center temperature of chicken breast. During storage, the decreasing rate of the breast center temperature was accelerated by cooling process. Scolding and cooling process also delayed the releasing of sarcoplasmic calcium and the decreasing of pH after slaughter. Other indicators such as the sarcomere length, metabolic enzyme activity, total glycolytic potential were not affected by the slaughter process.(2)After acute heat stress, pH value of chicken breast decreased faster, and brightness was significantly increased (47.7 rose to 55.2). At the same time, drip loss and protein solubility of breast meat were affected significantly by heat stress. The results of post-mortem glycolysis and oxidative damage detection were:?Pyruvate kinase activity and the concentration of sarcoplasmic calcium post-mortem were significantly increased by acute heat stress. Meanwhile, the effect of heat stress on Ca2+-ATPase activity was not significant.?CAT, SOD, GSH-Px activity in breast meat post-mortem was significantly increased by acute heat stress. The value of protein carbonyl and MDA in muscles were also significantly increased, which indicated that heat stress had interfered the oxidative balance in muscle post-mortem.Therefore, acute heat stress may had adverse effect on broiler meat quality, the reason was that heat stress accelerated the rate of glycolysis post-mortem and also caused oxidative damage, which lead to the excessive denaturation of protein in broiler meat.