Muscle Quality of Yellowfin Tuna (Thunnus albacares) Steaks After Treatment with Carbon Monoxide Gases and Filtered Wood Smoke

ABSTRACT

Treating seafood with carbon monoxide (CO) and various filtered wood smokes (FS) containing carbon monoxide has become a common practice in the industry, particularly for seafood intended for the frozen market. Tuna is one of the most common fish species treated with this process. Various quality improvement claims have been made for these treatments, which require investigation. Yellowfin tuna steaks were subjected to various CO treatments (4% CO, 18% CO and 100% CO) and FS treatment (which contained 18% CO) for 48 h, followed by 30 days of freezing and subsequent cold storage (4°C) after thawing. Muscle quality was evaluated after treatment. The FS, 18% CO and 100% CO treatments led to reductions in formation of secondary lipid oxidation products (TBARS) during freezing and subsequent cold storage, possibly due to increased stability of heme proteins. Textural studies using Instron compression tests on tuna steaks did not indicate significant differences (p > 0.05) between the CO or FS treatments compared with untreated controls. Water-holding studies (expressible moisture and drip loss) also did not show significant differences (p > 0.05) between CO- or FS-treated tuna compared with untreated controls. Freezing and thawing and subsequent cold storage did however lead to significant (p < 0.01) losses of water for all treatments. Muscle protein solubility tests, on the other hand, indicated that FS, 18% CO, and 100% CO-treated tuna steaks had proteins with higher salt solubility compared with untreated controls. This suggests that such treatments may stabilize muscle proteins, which was not apparent from textural and water-holding capacity studies.

Key Words:

• Carbon monoxide
• filtered smoke
• tuna
• quality
• lipid oxidation
• texture
• muscle proteins