Colour and colour stability of hot processed frozen minced beef. Results from chemical model experiments tested under storage conditions.

Minced beef based on hot processed meat was found to show an improved red colour and, more significantly, to show a better colour stability with respect to brown discoloration, when compared to minced beef resulting from a traditional (cold) process. The colour was followed by tristimulus colorimetry during freezer storage (product temperature -18°C) in a display cabinet illuminated by fluorescent tubes. The development of brown discoloration seems to indicate other oxidative changes and to relate to rancidity as judged from a determination of thiobarbituric acid reactive substances in the mince surface. Fluorescent light and added salt, both known from chemical models to increase the autoxidation rate of red oxymyoglobin to brown metmyoglobin, greatly reduced the colour stability, especially for cold deboned meat. pH of the hot deboned meat was significantly higher (pH > 6·0) than that of the cold deboned meat (pH ranged from 5·5 to 5·8). The observations are discussed in relation to kinetic salt effect on the acid catalyzed autoxidation of oxymyoglobin and its role in the initiation of oxidative rancidity.