Quality of frozen tuna meat thawed by three different methods

Abstract

Chie Yoneda Midori Kasai Keiko Hatae Yukiko Hirota Jun Nakamura Frozen blocks of bigeye tuna meat were thawed by three different methods: 1) slow thawing at 2°C for 24h and then at 20°C for 1h; 2) soaking in 3% salt water at 30°C for 1min, and then thawing at 2°C for 3h and finally at 20°C for 1h; 3) microwave irradiation for 3min while cooling at -20°C, and then thawing at 2°C for 1h and finally at 20°C for 1h. The quality of tuna meat thawed by each method was then examined. Parameters such as the proportional weight decrease, color change (a^*, b^*), and temperature change were related with the thawing rate. The final temperature of the tuna meat samples microwave thawed by methods 3 was significantly higher than that thawed by soaking in warm-salt water (methods 2). The pH value, molar percentage of ATP and related compounds, and toughness of the thawed meat were more affected by the freshness of the tuna meat than by the thawing method. A sensory test revealed that the tuna meat slowly thawed by methods 1 was darker than that thawed by the other two methods.