Effect of the slaughter method on the quality of raw and smoked eels (Anguilla anguilla L.)

Abstract

Eels (Anguilla anguilla L.) were slaughtered using two procedures. The commercial method consisted of desliming the fish in dry salt followed by evisceration. The alternative method consisted of stunning and killing in water with a combination of electricity and oxygen removal. Eels slaughtered as commercially exhibited aversive reactions and consequently a higher level of muscular activity before death. In raw fillets, differences appeared clearly between the two batches. The alternative slaughter by electricity and gas led to redder, firmer flesh with a higher pH. Myofibrillar proteolysis, lipid oxidation and loss of freshness (as evaluated by K-value) were reduced. After hot-smoking, which is a process that greatly modifies the fish flesh properties, differences between batches were less pronounced. However, eels slaughtered by the alternative method were characterized by a higher pH and a redder colour of the dark muscle, a desirable property form a commercial point of view. When assessed by sensory difference tests, appearance seemed to be the only attribute that allowed panellists to discriminate the two batches. Overall, it is concluded that slaughter by electricity and gas improved the quality of raw and smoked eels compared with the commercial method.