Freezing of mackerel filets in a two-step freezing process

摘要

Mackerel is a pelagic fish caught outside of the Norwegian coastline, mainly from September to November. Most of the fish is exported from Norway and most of it is transported whole and frozen, without gutting. There is an increased focus on improving the equipment and the processes for filleting of the mackerel to ensure a high-quality filet product as an alternative. This paper describes the freezing process of a new processing line in the south-west of Norway. The process consists of two freezers, one belt freezer and one spiral freezer, both attached to a centralized ammonia refrigeration system. Measurements of temperatures and other factors at the processing plant have been conducted and this has contributed to an optimized process, ensuring that the fillets have reached the intended temperature before they enter the freezing storage. Product quality and energy consumption has also been considered.