Whats the best way to keep fish fresh?

Fish and seafood needs to be kept fresh to reduce contamination and risk to human health on consumption. There are several technologies to help keep seafood and fish fresh, either by keeping then above freezing for quick consumption or by freezing them for long-term storage.

Block Ice Machine

Block Ice

Block ice can be used on smaller vessels out at sea. Block ice can be bought from an ice factory they normally come in 30-50kg blocks. These blocks stay frozen for long time, and can be transported on small fishing vessels for a day. At sea these blocks can be used, either by dipping in a bath of water, or by crushing the block ice, to keep fish or other marine life cool and fresh.

This is the most economical way of cooling seafood, as you do not require expensive onboard machines to produce ice. Which consumes energy and require regular maintenance.
However, the main disadvantage is that you cannot use this type of cooling for longer than a few days. as ultimately the block ice will melt.

Block ice is produced by block ice machines that are located on-land. Factories produce these blocks of ice for consumers in many industries, including the seafood industry. The machines are normally tank type or the newer, more efficient, direct-evaporator type.
A refrigeration engineer will help you select the right block ice system for you

Flake-ice machine

Flake Ice

Flake ice is great and economical way of producing ice for food preservation. It is simply spread over the catch layer by layer. The ice will maintain the fish temperature for long time and has a good surface area to cool every part of the fish. This will keep the fish and sealife fresh uniformly.

There are many ways to produce this ice, it can be produced in factory or onboard. Factory produced flake ice is not very popular for the marine industry. Due to the higher surface area of the ice, it tends to melt quicker than block ice.
Onboard flake ice machines are more popular. They are fitted onto fishing vessels and are able to operate using seawater. The onboard flake ice machines are constructed from higher grade stainless steel and are able to resist corrosion from seawater. The compressors of these machines have deeper oil sumps to protect against oil starvation caused by the movement of the waves against the vessels. Contact a refrigeration specialist on purchasing such equipment

Floor-mounted blast freezer Air-cooler

Blast freezing

Blast freezing in done on-land. Fresh fish is brought in to the factory and are flash frozen at -40C. Flash Freezing helps maintain texture and quality of seafood. They halt bacterial growth and comply with most local health standards.

Selecting blast freezing equipment required an expert refrigeration specialist to select the right indoor and outdoor units based on the type and quantity of product, and the speed to bring down temperatures. Typical blast freezing units comprise of aircooler and a standard aircooled 2-stage semi-hermetic condensing unit on R404a refrigerant. However for larger capacities, a water-cooled open-type screw compressor using R717(Ammonia) can be selected.