Smokehouses for fish

Types of Smoking

The smoked fish is treated with salt and dried in special furnaces with smoke formed by burning wood. 

Depending on the temperature of the process, there is cold-, hot-, and semi-hot fish. 

Cold-smoked fish is preliminarily salted, which guarantees long keeping limit. Hot-smoked fish is lightly salted, and the shelf life of such product is only a few days. 

The main conservation factor is the drying in the combustion products of wood, which have aseptic and antioxidant properties. 

Cold-smoking is a process of the drying that requires smoking temperature of 30°?. At this temperature there is no heat denaturation of the protein, and the final product has the qualities characteristic of salt-dried products with smoke flavor. Hot-smoked fish requires temperatures above 80°?. At this temperature, proteins denaturate, and muscle tissue partly dehydrates. 

The temperature for semi-hot smoking is from 60°? to 80°?, typically used for processing small fish.

Structure of a kiln

As a rule, kilns are made in prefabricated modular structures, comprising: 
• Smoke generator; 
• A fan for drying fish before smoking; 
• Aggregate box; 
• Control unit; 
• Cooling the smoke (if necessary). 

Smoke generators are designed to produce smoke. They are the most important functional part of the equipment, as thanks to properly designed system of distribution of smoke-air mixture inside a chamber fish is smoked evenly and quickly, giving the final product a good smell and a golden color. 

Smoke generators ensure the sustainability of the process by producing smoke of a stable quality. The composition of smoke depends on combustion temperature and type of wood. Products have the best taste when the fruit trees are used for smoking, but it is impossible to use it in industrial scale, that’s why hardwood is preferable: use oak, beech, linden, alder. 

Kilns can also be equipped with a cooling system of smoke, which allows effectively to cool the smoke-air mixture entering the smoke chamber. The cooling system allows getting necessary temperature of smoke. 
Cooling can take place based on a refrigeration unit or at the water cooler with tap water. 

There are different types of smoking furnaces in the fish-processing industry. The choice of construction depends on the type of processed products and on the characteristics of the production department.
Smoking devices can be divided into two main groups: continuous and intermittent operation.

Continuous devices include tunnel smoking chambers. They have efficient production, fully mechanized, and operated automatically. Such devices are designed for processing large numbers of fish of one species, strictly limited in size.

Smoking in tunnel furnaces is made by moving the product through the tunnel with a conveyor belt.

These constructions are good for short-term smoking products, and are generally used for processing small pieces of fish or fish liver.

Circulation of air in tunnel furnaces by means of fan speed and temperature are adjusted depending on the recipe.

Installation batch require some manual labor, and their productivity is less than that of continuously operating devices. However, such kilns can produce a wide range of products. Today, equipment manufacturers offer a universal smokinghouses, which allow the processing of the product both in hot and cold temperature. Smoking process realizes by constant circulation of air of the set temperature and humidity with the combustion products of wood inside the chamber.

Most manufacturers offer modular design of the smoking systems of intermittent action. Typically, each module is a separate heat chamber, which can be operated autonomously. Because of this, modular units can simultaneously produce multiple product lines of fish products.