Stunning and slaughtering processes may cause stress response in fish, seriously compromising their welfare and altering post-mortem biochemical processes. Due to this, effects on flesh quality during refrigerated storage could be hypothesized. Therefore, the study aimed to test four different stunning methods, namely anesthesia (AN), electroshock (ES), asphyxiation (ASP), and cold-shock (CS) consisting in a bath of cold water (-6 °C) added with salt, on rainbow trout (Oncorhynchus mykiss). Twelve fish per group were stunned then percussive slaughtered. Immediately, fish were filleted and the right fillets were utilized to extract ATP and related catabolites, to calculate the freshness index K-value and the Adenylate Energy Charge (AEC). Fillet quality was assessed on the other fillet immediately and after 14 days of refrigerated storage (+2 °C with ice covering). Immediately after death, the K-index was lower in AN, ES and CS than in ASP (0.527%; p<.05) while AEC was highest in AN and ES (0.936 and 0.878, respectively), and the lowest (0.664) in ASP (p<.0001). When fillets were analysed immediately after death, the different stunning methods led to large differences. The pH values were 6.37, 6.63, 6.66, and 7.24 in ASP, ES, CS and AN, respectively (p<.0001). Lightness (p=.051), yellowness (p<.001) and water holding capacity (p<.0001) were higher in AN than in the others, whereas texture did not differ. After 14 days, pH was lower in ASP than in all the other groups (p=.051). The remaining parameters did not vary between stunning methods after the short storage; however, a seemingly low MDA content was noticed in AN fillets and high in ASF ones, being 0.24 and 0.41 mg MDA-eq./100 g, respectively. Based on the results, the stunning method had a strong impact on energy metabolism and quality characteristics, suggesting that both ES and CS methods could be suitable for rainbow trout.
Electro and cold-shock are suitable stunning methods for rainbow trout (Oncorhynchus mykiss) considering energy metabolism and fillet quality / Giulia Secci, Lina Fernanda Pulido Rodriguez, Maria Vittoria Tignani, Leonardo Bruni, Filippo Faccenda, Adja Cristina Lira de Medeiros, Giuliana Parisi. - ELETTRONICO. - (2022).
Electro and cold-shock are suitable stunning methods for rainbow trout (Oncorhynchus mykiss) considering energy metabolism and fillet quality
Giulia Secci
;Lina Fernanda Pulido Rodriguez;Maria Vittoria Tignani;Leonardo Bruni;Adja Cristina Lira de Medeiros;Giuliana Parisi
2022
Abstract
Stunning and slaughtering processes may cause stress response in fish, seriously compromising their welfare and altering post-mortem biochemical processes. Due to this, effects on flesh quality during refrigerated storage could be hypothesized. Therefore, the study aimed to test four different stunning methods, namely anesthesia (AN), electroshock (ES), asphyxiation (ASP), and cold-shock (CS) consisting in a bath of cold water (-6 °C) added with salt, on rainbow trout (Oncorhynchus mykiss). Twelve fish per group were stunned then percussive slaughtered. Immediately, fish were filleted and the right fillets were utilized to extract ATP and related catabolites, to calculate the freshness index K-value and the Adenylate Energy Charge (AEC). Fillet quality was assessed on the other fillet immediately and after 14 days of refrigerated storage (+2 °C with ice covering). Immediately after death, the K-index was lower in AN, ES and CS than in ASP (0.527%; p<.05) while AEC was highest in AN and ES (0.936 and 0.878, respectively), and the lowest (0.664) in ASP (p<.0001). When fillets were analysed immediately after death, the different stunning methods led to large differences. The pH values were 6.37, 6.63, 6.66, and 7.24 in ASP, ES, CS and AN, respectively (p<.0001). Lightness (p=.051), yellowness (p<.001) and water holding capacity (p<.0001) were higher in AN than in the others, whereas texture did not differ. After 14 days, pH was lower in ASP than in all the other groups (p=.051). The remaining parameters did not vary between stunning methods after the short storage; however, a seemingly low MDA content was noticed in AN fillets and high in ASF ones, being 0.24 and 0.41 mg MDA-eq./100 g, respectively. Based on the results, the stunning method had a strong impact on energy metabolism and quality characteristics, suggesting that both ES and CS methods could be suitable for rainbow trout.
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