identification of boneless parts in silver carp (hypophthalmicthys molitrix) fillets

the silver carp (hypophthalmicthys molitrix) compnses about 50% to 85% of the composition offish species in the polyculture system of warm water species in iran. however, the difficulty in preparation of this species and the presence of pin 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 identify parts with less and/or no bones in silver carp fillets. the shape, size and location of bones found in the flesh were studied by three methods: enzyme digestion, cooking in hot water and x-ray scanning. results showed that except vertebral bones and ribs, the thin bones found in different parts of the flesh can be categorized into three groups: pin shaped, y shaped and non-regular shaped (several bifurcations). on the basis of density and arrangement of bones, we found that the fillets are made up of three different layers: external layer mostly of dark muscles and lipids with no bones, middle layer with the highest density of bones and the int mal layer which comprises about one third of the depth of fish flesh. the shape and arrangement of the bones in fish tail was significantly different. on the basis of recent findings, the deep part of the back and a narrow band on the upper part of the back are considered as boneless parts in silver carp.