Fish being an extremely perishable food is often preserved if it to be used in the future. These are several ways of preserving fish, but all these methods aim at extending the shelf life of this popular food. One of the most popular preservation methods is drying.
Generally, fish drying refers to the removal of water from fish. Although the term “fish drying” is often used to mean drying by evaporation, there are several other ways of removing water from fish. For example, if you salt fish or apply pressure on fish, the water in these fish will drain out. Removal of water acts to stop or slow down microbial or autolytic activity making it possible to store fish for a long time.
Several factors will determine the speed at which the fish dries. These include;
• Relative humidity – fish will dry faster in air that has little moisture content
• Air velocity – the faster the rate of air movement over the fish, the faster the fish will dry
• Air temperature – on a hotter day or in a warmer environment, the rate of evaporation is high resulting in a faster drying rate
• Surface area – the smaller the surface area, the faster fish dries.
As already mentioned, fish can be dried in several ways;
• Natural drying
This is when the energy of the wind and the sun are used in the entire process of drying. Several factors will determine the quality of the dried fish and how fast it takes to completely dry. Since air movement close to the ground is not very good, the fish should be raised to some level above the ground for faster drying. Most driers use raised slatted or mesh racks.
• Mechanical driers
Several types of mechanical driers exist which can be used in fish drying. The fish are dried in fan driven air streams. Usually this air is heated and may in some cases be re-circulated to improve relative humidity.
• Freeze drying
Here fish is placed in a vacuum and moisture loss is achieved due to the transfer of heat energy. Fish will start to dry as its moisture content approaches 15 percent. Even if the fish were allowed to freeze during drying, they would not shrink. Actually they would dry with a porous structure.
• Solar drying
One of the oldest methods of drying fish, solar drying involves the use of the sun’s energy to evaporate the water in fish. There are two ways of concentrating the suns energy on the fish;
a. Using parabolic reflectors
b. Using absorption units
Advantages of drying fish
There are several advantages of drying fish. These include;
• Dried fish are able to remain stable at the most ambient temperatures.
• Drying is a low cost way of preserving fish.
• Dried fish is highly concentrated in fish nutrients compared to fish preserved using other methods.
• Reduced water content means that there is less microbial action reducing fish spoilage.
Dried fish is highly nutritious and is available in major food stores. When buying, be careful about expiry dates and additives. Dried fish is eaten just like most other fish; either made into stew or eaten in their dry form…just make sure it gets to the stomach.