Oxymyoglobin formation in meat and poultry

The rate of oxymyoglobin formation (blooming) was estimated, by reflectance spectrophotometry and depth of oxygen penetration, of beef and pork 1. dorsi and chicken breast muscles of normal ultimate pH. Although beef bloomed very rapidly when exposed to air, even at 23°C, pork muscle exhibited little evidence of oxymyoglobin formation at this temperature and no chicken muscle produced oxymyoglobin at 23°C. Even after 48 h at 5°C there was little evidence of oxymyoglobin formation in the chicken muscles although formation was evident in the pork samples. After only 24 h storage at 5°C it was apparent that both the chicken and pork muscles oxidised to produce some metmyoglobin at their surface, though the amount produced was apparently more in the chicken than the pork samples. In most chicken samples held in air at 5°C the predominant pigments were the purple reduced myoglobin and brown metmyoglobin. The implication of these observations in relation to the packaging of chicken portions is discussed.