How stunning methods affect the quality of Nile tilapia meat

Nile tilapia, Oreochromis niloticus, is one of the most cultivated fish species in Brazil. However, few studies evaluate how the stunning methods affect the meat quality of this fish. This study evaluates how both stunning methods, iced water and CO2 narcosis, affect the quality of tilapia meat that was stored refrigerated in ice (4 degrees C) for up to 26 days. Tilapia stunned by CO2 narcosis showed less stress compared to iced water, which was evidenced by the higher ATP, and better meat color as well, evidenced by higher lightness (L*) and lower redness (a*) values. After sensorial analysis, fish were classified as extra-fresh during the first 2 days of storage; as fresh from day 3 to day 14, not fresh from day 15 to day 23; and as spoiled from day 23 onwards. Stunning of tilapia by CO2 narcosis can be an alternative to the traditional method of desensitization (iced water) used in Brazil.