Morphometry, slaughtering performances, chemical and fatty acid composition of the protected designation of origin ‘‘Golden hump tench of Poirino highland’’ product

One hundred and thirty-two tench were photographed and a total of 13 landmarks were identified. Fish were grouped in four size classes on length basis and different shape descriptors were computed. Landmark configurations were superimposed. Size was computed as centroid size. The roundness coefficient, the log(partial area)/log(total area) ratio and the condition coefficient were calculated. Slaughtering performances and fillet composition analyses were performed. Shape variability was found primarily on cephalic area while head and tail regions were more homogeneous. A high correlation between centroid size and total length was found as well as a higher increase of the partial area than the total area justifying the hump shape of this tench. The scatter of relative warp 1 scores and centroid size for the four size classes has showed, with the increase of the length, a larger number of specimens that were characterised by a deep profile. Geometric morphometric approach produced a valuable tool in defining morphospaces for tench. Condition coefficient ranged from 1.24 to 1.29, without any significant difference among the size classes. Slaughtering performance resulted in agreement with those reported by other authors while VSI was lower. In fillets, the fatty acid profile was composed of about 30% of saturated fatty acids, 50% of monounsaturated fatty acids and 20% of polyunsaturated fatty acids with about 8% of docosahexaenoic acid. Atherogenic and thrombogenic indices were 0.58 and 0.42, respectively. Both n6/n3 and polyunsaturated/saturated fatty acids ratios were in accordance with value recommended for a healthy nutrition giving positive evaluation of the nutritional qualities of tench.