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Title: CHEMICAL CHARACTERIZATION OF LIVER LIPID AND PROTEIN FROM COLD-WATER FISH SPECIES

Author
item Bechtel, Peter
item OLIVEIRA, ALEXANDRA - UNIV. OF ALASKA, FITC

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2006
Publication Date: 8/20/2006
Citation: Bechtel, P.J., Oliveira, A. 2006. Chemical characterization of liver lipid and protein from cold-water fish species. Journal of Food Science Vol. 71(6):S480-S485.

Interpretive Summary: The annual fish harvest from Alaska waters is in excess of two million metric tons and currently fish livers are combined with other byproducts and made into fish meal and oil or discarded. Whole livers can be utilized or the lipid and protein components separated and used to make food and feed ingredients. The objective of this study was to characterize and compare the lipid and protein characteristics from commercially important cold-water marine species harvested in Alaska and also underutilized species such as arrow tooth flounder. Lipids from livers of seven different Alaska fish species including walleye pollock, pink salmon, big mouth sculpin, pacific halibut, arrow tooth flounder, flat head sole and spiny head rock fish, were characterized. Differences between species were found in fatty acid profiles, total polyunsaturated fatty acid content, omega-3 fatty acid content and omega-3/omega-6 fatty acid ratios. The amino acid profiles indicated that the liver protein samples from the different species contained high levels of essential amino acids and were of high quality. These lipid and protein properties can be used to formulate unique food and feed ingredients from the livers of cold-water marine fish.

Technical Abstract: In Alaska, fish livers are combined with other byproducts and made into fish meal and oil or discarded. The purpose of this study was to chemically characterize liver lipids and proteins from walleye pollock (WP), pink salmon (PS), big mouth sculpin (BS), pacific halibut (PH), arrow tooth flounder (AF), flat head sole (FS) and spiny head rock fish (RF). Liver lipid content ranged from 50.3% in WP to 3.3% in PS. Protein content ranged from 7.7% in WP to 18.4% in BS. PS livers had the highest content of omega-3 fatty acids at 336 mg/g of oil. Triacyglyceride levels in all liver tissues ranged from 78% in BS to 97% in RF, and were inversely proportional to phospholipid content. There were significant differences in the content of nine amino acids with methionine and lysine values ranging from 2.66% to 3.43% and 7.19% to 9.45% of the total amino acids, respectively. Livers had distinct chemical properties and can be used for the development of unique ingredients for the manufacturing of specialized food and feed ingredients.