Brine freezing of mackerel may reduce the time for freezing in the air tunnel by 50%
Brine freezing of mackerel
Fish processing industry
Reduction of energy consumption (10-20%) and time (50%) during freezing of fis
Freezing of pelagic fish is done in air tunnels where mackerel and herring are packed in 20 kg cardboard boxes and put on racks. Huge amounts of fish are frozen in batch, and typically 100-300 tons are frozen within 20-22 hours in each tunnel. Large fans are circulating the air in the tunnel, and the heat transfer gets lower towards the end of the freezing period.
By partly freeze the mackerel in a brine freezer before entering the air tunnels, the goal is to reduce the freezing time in the tunnel to 11 hours. The capacity of the plant may therefore be doubled compared with today’s production. Brine freezing is about 50% more energy efficient than air tunnels, in addition, the air tunnels get more energy effective when lowering freezing time. The challenge is to partly freeze the mackerel to a level where the amount of ice is high, but the stiffness is still low enough to get 20 kg in each cardboard box. Also, the technical aspects for brine-freezing large amounts will be considered.
Totally it’s expected to lower the energy consumption by 10-20%, and even higher if the process is optimized.