Fish products and Byproducts Technology

Unit 4 - Fish preservation by smoking

4.3. Types of smoking
Based on the temperature at which the process is carried out, smoking can be characterized into two types.

• Cold smoking
• Hot smoking

What is cold smoking?
Carrying out the smoking process at a temperature upto 30^oC is called cold smoking, in which cooking of the flesh does not occur.
Smoking effect is mainly due to the chemicals killing off the surface bacteria as reduction in water is not significant.
Cold smoked products should be cooked before consumption
Cold smoking takes 2-4 hrs when using a mechanical smoking kiln
What is hot smoking?
Carrying out the smoking process in which the fish is exposed to increasing temperatures up to at least 70^oC is called hot smoking. It is having following effects

• The fish will be cooked
• Enzymes will be destroyed and chemical spoilage will be reduced
• Surface bacteria will be killed

How hot smoking is carried out?
In a mechanical kiln, hot smoking is carried out in three stages.

• A preliminary drying period at about 30°C. During this time the skin is toughened to prevent breakage occurring in the remainder of the process.
• A smoking and partial cooking period at 50°C
• A final cooking period at 80°C

The total time could be up to 3 hours. The actual times of each stage will depend upon:

• The species
• The size and thickness
• The fat content of the product
• The loading of the kiln
• The colour and taste requirements

Is it cooling necessary for hot smoked products before we pack?
Yes. If the product is packed in a warm condition mould is encouraged to grow.It is necessary to avoid the product turning mouldy. Products should be cooled down to room temperature then stored in chill room.