Functional properties of enzymically hydrolysed fish waste

Enzymic hydrolysis of cod fish waste was investigated using two enzymes (trypsin and bromelain). A fish protein hydrolysate (FPH) powder and frozen flake hydrolysate were produced using a spray drier and an ice flake machine. Functional properties of the FPH were assessed with respect to the molecular weight (MW) spectrum. The characteristics of solubility and emulsification for the hydrolysate showed it to be suitable for use as a binder compared with egg albumin (EA) and soy bean isolate (ISB) for fish products. Fishburgers with improved texture, succulence and reasonable cooking losses were made successfully from cod fish mince incorporating a vegetable oil/water emulsion stabilised by FPH. Taste panels were carried out and overall acceptability of the fishburgers made from the FPH emulsion was better than fishburgers containing EA and ISB emulsions. Economic evaluation and specification of a pilot plant were done for both FPH powder and frozen flake hydrolysate production. This work strongly emphasises that FPH should only be used in fish products which need a good binder and where the flavour/taint problems of use in other products, e.g. beverages, pasta, will not arise.