マグロ肉色とメトミオグロビン還元酵素活性との関係について-II

Abstract

The changes in the activity of metmyoglobin reductase during frozen-storage and sub-sequent thawing of big-eye tuna meat were examined in order to elucidate whether the activity of metmyoglobin reductase is useful as an index in quality testing, especially in the evaluation of the colour of frozen-stored big-eye tuna meat, and also whether the prediction of the colour of meat after thawing is possible. During frozen-storage at -20°C the activity of metmyoglobin reductase decreased rapidly with marked formation of metmyoglobin. On the other hand at -30°C and -40°C the decrease in the activity was not so large and the red colour of meat was satisfactorily retained. The activity decreased remarkably during thawing and storage at 3°C for 18 hr in the tuna meat stored at -20°C and -30°C, but not in the meat stored at -40°C. In the former meat samples, the formation of metmyoglobin in the course of thawing and subsequent storage was remarkable. These results suggest that the activity of metmyo-globin reductase could be a useful index in the quality evaluation of tuna meat, especially in respect of the colour.