冷凍マグロ肉の肉色保持に関する研究-V

Abstract

The effect of freezing rate of tuna meat on its discoloration during storage was examined. The results obtained are summarized as follows: In the first experiment, meat blocks (3×3×3cm) were cooled to -10°C at the innermost portion either slowly in still air at -10°C or rapidly in alcohol containing dry-ice, and stored for one month at -10°C. The rate of discoloration during the storage was slightly slower with the rapidly frozen meat than with the slowly frozen (Fig. 1). In the second experiment, meat blocks (3×3×3cm) cooled either to -5°C in still air at -3 ?? -7°C or to -20°C in alcohol containing dry-ice, were stored for 60 days at both -20°C and -33°C (Fig. 2). At -20°C, the rate of discoloration was about the same at the surface between the slowly and rapidly frozen samples, while not at the deep portion: The rate was clearly slower with the rapidly frozen meat than with the slowly frozen meat in the early phase of storage. This difference, however, gradually disappeared. A similar tendency with the deep portion was noted again at -33°C, all over the period of storage this time. From those results, it may be concluded that the freezing rate is to some degree important for retaining the red color of frozen tuna meat, especially in a short time storage.