Effects of pH and temperature on metmyoglobin solubility in a model system
2002
Zhu, L.G. | Brewer, M.S.
From a series of experiments heating metmyoglobin solutions at pH 5.0 through 7.0, the effects of temperature and pH on the thermal stability of metmyoglobin were investigated. The percent metmyoglobin denatured at temperatures from 25 to 80 degrees C was determined. pHs lower than 6.5 caused metmyoglobin denaturation at various temperatures from 25 to 80 degrees C, but it was particularly apparent when pH was < 5.6. Thermal stability of metmyoglobin increased as pH increased. Metmyoglobin denaturation occurred at 55 degrees C at pH 5, however, denaturation did not occur until 60 degrees C at pHs from 5.3 to 7.0. A slower heating rate (0.9 degrees C/min) resulted in more metmyoglobin thermal denaturation than a faster heating rate (1.3 degrees C/min) when the temperature was above 55 to 60 degrees C. The denaturation caused by low pH alone was reversible, while that caused by high temperature was not. Techniques which increase muscle pH, such as the injection of sodium bicarbonate, could effectively improve the color condition of PSE meat.
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