Fish products and Byproducts Technology

Unit 3- Salting and Drying

3.1.4. Factors of salt to be considered before using for salting
What are the factors related to salt to be considered before using for salting?

• Physical properties
• Chemical impurities
• Microbiological contamination

Effect of physical properties on salting
A mixture of large and small grain sizes is recommended for any salting of fish. If fine grain is used directly on the fish, salt burn may occur due to the rapid removal of water from the surface and no penetration of salt to the interior of the fish.
Main chemical impurities of commercial salt and their effect on salting

• Calcium chlorides and sulphates
• Magnesium chlorides and sulphates
• Sodium sulphate and carbonate
• Traces of copper and iron

Calcium and magnesium chlorides slow down the penetration of salt into the fish, thus increasing the spoilage rate.
Magnesium chloride is hygroscopic in nature and tends to absorb water thus making the fish more difficult to dry.
Excessive quantities of calcium and magnesium compounds impart a bitter taste to the fish and make it brittle when dry.
Traces of copper gives a brown appearance to the fish making it look spoiled.

Microbial contamination of salt and their effect on salted products
Halophilic bacteria are present in most commercial salt. A particular group of halophiles called Red / Pink cause reddening of wet or partially dried salted fish. These do not grow in brine or in fully dried fish.
Halophilic moulds on the other hand tend to grow on fully dry fish, causing dark patches. These are called “dun”.