Evaluating Fish Fillet Quality: A Comparative Analysis Of The Effects Of Mechanical Bleeding (Percussive Stunning) and Electrical Stunning Techniques On Rainbow Trout(Oncorhynchus mykiss)
Abstract
The fish and seafood industry employs diverse methods, resulting in inconsistent quality of fillets and products, negatively affecting marketability and customer satisfaction. Consistent quality is essential, making effective bleeding techniques critical for improving the appearance and overall quality of fillets. This study compares the effects of electrical stunning and mechanical bleeding on fish quality. Quality indicators including core temperature, degree of rigor, elasticity, softness, blood spots, and gaping were evaluated. Additionally, industrial assessments were conducted to ensure cut accuracy and post-gutting cleanliness.
The results show that fish processed with electrical stunning had a more stable core temperature within 30 minutes, while mechanical bleeding caused more fluctuations. Electrical stunning led to a rapid rigor mortis onset within 8 hours, whereas mechanical bleeding delayed it and did not even reach the equivalent level as electrical method in 13.5 hours post stunning, maintaining postponed rigor over time to have a better quality. Mechanical bleeding resulted in softer but less elastic fillets and whole fish, with few blood spots. However, mechanical bleeding had less gaping score on fillet but higher gaping score on whole fish. Industrial tests revealed fewer incorrect cuts with mechanical bleeding, although post-gutting cleanliness was better with electrical stunning. Overall, given the suboptimal circumstances for mechanical bleeding, it provided significantly better fillet quality, despite some advantages of electrical stunning in whole fish quality.