Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2003
Publication Date: 6/20/2003
Citation: Bechtel, P.J. 2003. Properties of Different Fish Processing By-Products From Pollock, Cod and Salmon. Journal of Food Processing and Preservation. 27(2):101-116. Interpretive Summary: Over one million metric tons of fish processing waste is produced each year from fish harvested in Alaska; however, much of the waste in not utilized. The objective was to evaluate the composition and properties of fish processing waste components. Major components of fish processing wastes from both Alaskan pollock and Pacific cod are heads, viscera, frames and skins. For pink salmon the two major waste components are heads and viscera. There were compositional differences between different waste components and also between species. Protein solubility was greatest for viscera samples before heating and fish skin samples after heating. Connective tissue is an important parameter effecting processing properties and nutritional value. Skin had the greatest connective tissue content followed by frames and heads. Estimated rat protein efficiency ratios (PER values) ranged from a low of 2.1 for skin to a high of 3.1 for viscera and fillet. This study identifies important properties of fish processing waste stream components that could be used to create new products and feed ingredients. These results will be of value to the fish processing and byproduct industries.
Technical Abstract: Individual fish processing waste stream components can be used to make feed ingredients or other products. Waste stream components obtained from commercial fish processing plants included heads, viscera, frames, and skins from Alaska pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus); and heads, and viscera from pink salmon (Oncorhunchus gorbuscha). The protein content of heads from all three species ranged from 13.9 to 16.4%; and the fat content ranged from 0.9 to 10.9%. Viscera protein content ranged from 13.0 to 15.3%, and the fat content from 2.0 to 19.1%. After heating to 85C, the percent soluble protein in salmon heads was different (P<0.05) from pollock or cod heads. Percent soluble protein of pollock and cod skin increased 8 fold (P<0.05) after the 85C heat treatment. Connective tissue content was calculated from chemical determination of hydroxyproline content, and large differences in percent connective tissue content were found (1% for pollock viscera to 46% for skin). Estimated rat PER values ranged from a low of 2.1 for skin to a high of 3.1 for viscera and fillet samples (P<0.05). Frames, head and viscera had estimated rat PER values ranging from 2.85 to 3.13 with small differences between species.