ARS | Publication request: PROPERTIES OF STICKWATER FROM FISH PROCESSING BYPRODUCTS

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: January 20, 2004
Publication Date: December 20, 2004
Citation: Bechtel, P.J. 2004. Properties of stickwater from fish processing byproducts. Annual Meeting of the Institute of Food Technologists, Book of Abstracts 63-5:152.

Technical Abstract: The first steps in fishmeal production are usually cooking of whole fish or fish processing byproducts and then pressing to produce a press cake and an aqueous fraction. After the oil is removed from the aqueous phase it is referred to as stick water. Stick water contains a substantial percent of the total protein as well as other soluble components. The objective of this study was to determine selected chemical and nutritional properties of stick water protein obtained from the processing of fish processing byproducts. Four samples of stick water were obtained from a commercial fishmeal plant in Alaska. Raw material for three samples was Pollock and cod fish processing byproducts and one was salmon processing byproducts. Stick water samples were taken after oil removal but before concentration and were then freeze dried in the laboratory. Samples were analyzed for protein, lipid, ash, moisture, amino acid and mineral contents, percent connective tissue, protein digestibility, and proteins molecular weight by SDS electrophoresis. Stick water samples were approximately 6% protein, and after freeze dying samples were 70.5 to 86.2% protein, 10.6 to 13.9 % ash, with variable amounts of lipid. The pH ranged from 6.5 to 7.0. Samples had high levels of proline and hydroxyproline and calculated connective tissue protein as a percent of total protein was 22.8 to 25.7%. On a dry matter basis calcium content was below 0.1% and potassium content was 1.7 to 2.8 %. Percent soluble protein ranged from 54 to 70% at 30C. Protein degradation appeared limited and major proteins had molecular weights of 198,000, 120,000 and 39,000. Protein digestibility using pepsin was in excess of 95%. It is possible to make a protein ingredient from stick water with interesting chemical and functional properties.