Researchers from Chalmers University of Technology devised a way to elongate the life of less desirable fish by-products and turn them into valuable products. The goal was to upgrade by-products and reducietheir use in animal feed and waste.

When herring is filleted, over half of the fish’s weight becomes low-value “sidestream” products that never reach the plate. Sidestream products may seem useless but they are full of proteins and healthy omega 3 fatty acids. The team created a dipping solution that can extend shelf life and increase food opportunities. Source: Chalmers UniversitySource: Chalmers University

The biggest challenge was that unsaturated fatty acids in fish are sensitive to oxidative degradation, which means quality decreases after just a few hours. These parts are sensitive because they are rich in blood.

The dipping solution keeps sidestreams fresh for longer by covering parts with a thin layer of antioxidants.

Testing proved that dipping sidestream parts from the herring filleting process into the new solution significantly extended the product’s lifetime. At 20° C, sidestream storage time could be extended to over three and a half days. At 0° C, storage time could be extended to 11 days. The solution could also be reused up to ten times, thereby minimizing waste, and rancidity would still be inhibited at 0° C.

Sidestreams from fish are valuable, even if they do not appear to be. The backbones and heads can be used as fish mince or as a protein ingredient. The belly flap and intestines can be used in oil production. The tail fin can be used in marine collagen production. But without a method to preserve freshness, these materials just become waste.

A paper on the new dipping solution was published in Food Control.