Upgrading Marine Oils from Cod (Gadus morhua) On-Board the Deep-Sea Vessels-From Waste to Value

Significant amounts of marine raw material are lost on-board the deep-sea vessels due to fast quality degradation. Optimal on-board handling and processing strategies can upgrade these resources from waste to food ingredients rich in nutrients such as omega-3 fatty acids. The objective of this study was to investigate the effect of raw material freshness and sorting on the quality, composition and yield of oil produced thermally from cod (Gadus morhua) residuals on-board a commercial trawler. Oil was produced from whole viscera fractions with liver or out-sorted livers right after a catch and after chilled storage for up to 6 days. The results showed that significantly higher oil yields could be obtained if the raw materials were stored for 1 day or longer. However, an undesired emulsion was formed when viscera were stored for 4 days. All oils were rich in health beneficial omega-3 fatty acids, but viscera oils had generally lower quality with higher levels of free fatty acids and oxidation products. However, out-sorting of the liver was not necessary to meet guidelines for high-quality fish oil. Both viscera and liver could be stored for up to 2 days at 4 degrees C prior to oil production and still meet quality criteria for food applications. These results demonstrate a large potential in upgrading currently wasted marine raw materials into high-quality food ingredients.

Automated summary

Large quantities of marine raw material are lost on-board deep-sea vessels due to fast quality degradation. This study investigated the effect of raw material freshness and sorting on the quality, composition, and yield of thermally produced oil from cod residuals on a commercial trawler. The results showed that longer storage time resulted in higher oil yields, but an undesired emulsion formed after 4 days of storage. However, both viscera and liver could be stored for up to 2 days and still meet quality criteria for food applications.