The use of special parts of Silver carp(Hypophthalmichthys molitrix To produce fillet.

The increasing demands of the growing populations can be met by developing aquaculture. However in order to provide suitable grounds for consumption which is acceptable to different conditions and tastes, apart from producing a variety of products we also need to improve the methods of marketing and consumption. The silver carp (Hypophthalmicthys molitrix) comprises about 50 to 85% of the composition of fish species in the polyculture of warm water species in Iran. However the difficulty in pretreatment and the presence of intermuscular bones are among the main reasons to restrict the demand of this species in the domestic markets, particularly in non-coastal provinces. The objective of this study was to develop a technology to produce high quality and acceptable fillet using special parts of silver carp. Fillets were prepared from small (400-700 g), medium (1100-1400 g) and large (1800-2100 g) sizes. The size and location of intermuscular bones and ultimately the identification of suitable parts which can be used to produce boneless filletts was carried out by enzymatic digestion, cooking in hot water and X-ray scanning. The total filleting yield of large and small silver carp was 53.4 ± 2.8% and 42.6 ± 1.9 %, respectively which was significantly different from that obtained (50.3 ± 2.4%) from medium size (P 0.05). On the basis of density and arrangement of bones the thickness of fillets is made up of three layers; external layer (superficial) which is mostly made of dark muscles and lipids, middle layer with the highest density of bones and the internal layer which comprises about one third of the depth of fish flesh. The deep part and an upper part on the back (loin) are considered as boneless parts in silver carp. The filleting yield of each part was between 8 to 9% in a large fish. Sensory evaluation of samples showed that the few small remaining bones turned crisp and dissolved during frying and will not cause harm during consumption. Odor, flavor, taste, texture and the overall acceptability of fried samples was evaluated as very good. The results of testing deheading (Baader 1741), filletting (Baader 200) and skinning (Baader 52) machines showed that they can be used to produce fillets from silver carp and improve the yield by 3-5% as compared to that using hand. It seems that the commercial production of fillet with less and/or no bones from silver carp using manual methods is not cost effective. A combination of man and machines is recommended in different stages.