Texture and colour properties of proteins recovered from whole gutted silver carp (Hypophthalmichthys molitrix) using isoelectric solubilisation/precipitation

BACKGROUND: According to an FAO report, carp are the cheapest and by far the most commonly consumed fish in the world. Carp have minimal growth requirements, yet rapid growth rates. Although carp are generally considered unsuitable for human consumption in the USA, they have rapidly started populating major bodies of fresh water in the USA to the extent that commercial processing becomes of interest. However, typical mechanical means of meat recovery from carp are impractical owing to the bony nature of the carp carcass. Therefore the aim of the present study was to devise processing strategies to recover fish meat from carp that could be used in the development of human food products. RESULTS: Isoelectric solubilisation/precipitation at acidic and basic pH values was applied to whole gutted silver carp. Depending on the solubilisation pH, protein and fat recovery yields were approximately 420-660 and 800-950 g kg(-1) respectively. The process effectively removed impurities such as bones, scales, skin, fins, etc. from whole gutted carp. The proteins were concentrated to approximately 900 g kg(-1), while the fat was reduced by 970-990 g kg-1. Functional additives (potato starch, beef plasma protein, transglutaminase and polyphosphate) improved (P < 0.05) the texture of carp protein-based gels such that it was generally comparable to the texture of Alaska pollock surimi gels. Although titanium dioxide improved (P < 0.05) the whiteness of carp gels, it was lower (P < 0.05) than the whiteness of Alaska pollock surimi gels. CONCLUSION: Isoelectric solublisation/precipitation allows protein and lipid recovery from whole gutted carp. However, if the proteins are used as a gelling ingredient in fish food products, functional additives are recommended. (C) 2008 Society of Chemical Industry