ARS | Publication request: Chemical and Nutritional Characteristics of long nose skate (Raja rhina) byproducts from Alaska

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2009
Publication Date: N/A

Technical Abstract: Skates have recently become a small commercial fishery in Alaska and along the western United States coast, but have long been associated with bycatch. The fins are marketed as "skate wings" and mainly sold fresh, frozen, and dried or salted and dehydrated for Asian markets. Byproducts generated include the large body with head attached and viscera intact. Most of the skate byproduct is discarded or made into meal; therefore, there is opportunity to enhance the utilization for skate byproducts . The objective of this research project was to chemically characterize the long nose skate (Raja rhina) byproducts from Alaska. Bodies of six long nose skates, caught off the coast of Kodiak were obtained immediately after the wings had been removed by a commercial processor. Each skate body was separated into three categories: body (minus viscera), viscera (minus liver), and liver. The following analyses were performed on the separated parts: proximate composition, minerals, amino acids, fat soluble vitamins, protein gel electrophoresis, fatty acid methyl ester profiles, thiobarbituric acid reactive substances (TBARS), and biogenic amines (BA). Proximate composition of the body and viscera consisted mainly of moisture at approximately 81% followed by protein at 19%. Livers were comprised mainly of lipid at 50%. High levels of alpha-tocopherol were noted in the livers ranging from 158±15 ug/ g liver in one individual to 46±13 ug/ g liver in another. Average concentrations of EPA and DHA were high in the extracted liver oil at 16 and 18 wt/wt%. The average lysine content for the individual byproduct components was 4.17 in body, 6.4 in liver and 5.55 wt/wt% in viscera. Average TBARS values were low for the body, viscera and liver at 0.6, 1.3 and 1.5 ug MDA/ g byproduct. The BA histamine was only detected in the viscera at an average concentration of 11.1 ug/g byproduct. Results suggest skate byproducts can be used as a raw material source for unique protein and lipid products.