La Sardina (Sardina pilchardus): estudi de la condició fisiològica, parasitologia i durabilitat comercial

Abstract

The sardine (Sardina pilchardus) is a pelagic cold-water fatty fish species usually caught in the Mediterranean and it is a very healthy species because of its high content of omega-3 fatty acids. It is well known that the sardine is not usually infected by Anisakis nematodes, which are the origin of some human allergies and whose presence is very common in commercial species. During the last few years, an exhaustion of the sardine has been observed: its capture and quality have decreased. For this reason, and because of its importance in gastronomy, economy and health, we have focused the project on this species. In order to do so, the study has been divided in three sections: the physiological condition of the fish, the parasitological study and finally the analysis of the commercial durability. In relation to the physiological condition of the sardine, it has been found out that it is now under what is considered a good condition; the cause should be attributed to external factors (climate change and overfishing), and internal factors related to the biology of the species, since when the study was carried out, the sardines were in the active phase of their reproductive cycle. Related to the parasitological analysis, the absence of the Anisakis parasites has been demonstrated. In fact, only the nematode Hysterothylacium aduncum and some Digenea trematodes have been identified. However, it has been detected a prevalence and intensity of H. aduncum in the third larvae stage (L3) and in the advanced third stage larvae (L3-4), which has never been reported in the sardine. This fact may produce negative effects on human health, bearing in mind that some allergy cases in humans have been related to this parasite. On the other hand, the infection of H. aduncum can cause the sardine’s exhaustion and an increase in its susceptibility to infections. Nevertheless, in this study we didn’t find significant differences between the physiological condition of infected sardines and not infected sardines. Finally, for the study of the conservation and durability of the fish, we have applied the qualitative sensory method, called QIM. Results showed that the most indicative attributes, in order to value the quality of the sardine, are the odour of the gills, the eyes’ appearance and the state of the abdomen. Moreover, it has been determined that the shelf-life of the sardine is about 3-4 days, and the importance of the way the fish is kept since the capture has also been demonstrated. Finally, in order to prolong the shelf-life of the sardine it has been proposed to improve quality by washing the fish just after it has been caught, which has been demonstrated effective in other species