EFFECT OF FREEZING, EXPOSURE TO ENHANCEMENT SOLUTION AND MODIFIED ATMOSPHERE ON PORK BONE DISCOLORATION

The objective of this study was to develop a model system to evaluate the effects of freezing, exposure to enhancement solution and modified atmosphere on discoloration of pork rib bones. Bones were removed from carcasses, split along the transverse plane, then frozen (−20C) or held at 4C for 24 h. Half of each temperature pretreatment group was exposed to a 4% phosphate/4% NaCl enhancement solution, while half served as controls. Samples were packaged in modified atmosphere packaging (80% O2/20% CO2) or air and displayed in a retail case (4C, 24 h). Visual discoloration occurred during the first 10 h of display; additional visual darkening (brown, green/black) occurred in previously frozen samples, while refrigerated samples remained redder. After 24 h, Commission Internationale de l'Eclairage L*, a* and b* values indicated that previously frozen samples were darker and less red. The frozen samples contained more methemoglobin per gram of protein than those that had never been frozen.