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Fish Drying

CFW produces drying equipment with close temperature and air speed control for a variety of applications, including fish drying. Our experience with air technologies has led to continuous improvements in our products.

dried fish on white background

CFW's experience with industrial and commercial drying systems has enabled us to offer equipment that is:

  • Cost effective and simple to operate
  • Energy efficient
  • Capable of even drying, with well-distributed airflows
  • Accurate in supplying air of the desired temperature and humidity
  • Reliable, with robust construction
  • Minimises odour nuisances
Fish drying helps to preserve it by slowing down, or even stopping, deterioration from many chemical processes and microorganisms. Drying alone is not enough to stop oxidation. Mechanical fish drying has many advantages:
  • Minimising product contamination from dust, rain, or insect infestation
  • Reducing the risk of spoilage from microbial or enzymatic activity
  • The product is concentrated, reducing transport costs
  • Faster total drying times
  • More consistent production speeds and quality

A variety of equipment is used for fish drying. This includes cabinet, kiln, solar tent, tunnel and spray driers. Heated-air drying of fish has employed temperatures varying from 25-50 °C. With drying temperatures that are higher, the fish tends to cook. While uncooked fish can be dried to internal moistures of as low as 11%, cooking causes fish to begin losing its integrity at moisture levels below 30%, causing it to disintegrate when handled. Temperatures should generally be kept below 30 °C for temperate marine fish and 45 °C for tropical marine fish.

During the initial stage of drying – the constant-rate drying period - the surface of the fish is moisture-saturated at the wet-bulb air temperature and it dries at a constant rate. When the surface gets dry, evaporation continues from inside the fish. During this falling-rate drying period, the rate of ambient air flow becomes less important, so that the rate of drying slows. Drying stops when the moisture in the fish is at equilibrium humidity, a variable which is itself dependent on the relative humidity of the ambient air. The low temperatures needed for heated-air drying mean that diffusion from the inner part of the fish to the surface remains relatively slow, so that drying times remain long.

However, systems programmed to raise temperatures progressively through the drying process instead of keeping temperatures constant can accelerate drying. In these systems, a maximum temperature of up to 115 °C is reached towards the end of the drying process without cooking the fish.

The use of low initial temperatures for drying fish has also led producers to employ desiccant dehumidifiers.

Fish drying can be done throughout the year and in all weathers by using indoor hot-air systems, making it possible to export shipments regularly. This method also takes much less time, resulting in reduced risks of microbial and insect contamination, and results in a product with consistent moisture content and quality.