Back and Next - Back and NextPreservation of Fish
Monday, January 26, 2009
A fish is a vertebrate and a cold-blooded animal with gills and fins living wholly in water. It is a rich source of protein.
It has become a predominant consumable food among Gambian families. Therefore preservation of this major staple food needs to be giving special attention. The micro flora of living fish depends on the microbial contents of the water in which they live. Fish micro flora include bacteria such as Species of Pseudomonas, Alcaligenes, Vibrio, Serratia and Micrococcus. The level of contamination can increase with the type of processing and handling.
Fish are also susceptible to autolysis, oxidation and lipolysis in addition to microbial spoilage. Their preservation, therefore, should involve a combination of treatments. Evisceration should be done immediately after harvesting, to prevent the gut enzymes from becoming functional. Preservation of fish by chilling temperatures is said to be only a temporary method though freezing is recommended as the best way to preserve fish for a longer time. Freezing kills most organisms but not the psychrophiles and the spores.
Most of these survive freezing and grow during thawing. Fish preservation by radiation has been tried and found successful especially when used in combination with freezing. Salting and drying methods of fish preservation are other means of fish preservation in The Gambia.
Sodium chloride serves as a chemical preservative and binds the moisture. This may, however, not affect the halophiles which sometime cause discolouration during drying. Other chemicals used in fish preservation to retard microbial activity include sodium and potassium nitrite and nitrate, benzoate and sorbate.
A dip in antibiotic solutions has been tried and found successful but these days, it is not encouraged. The kind and rate of fish spoilage varies with a number of factors, such as the kind of fish, the condition of the fish, the level of contamination, the storage temperature and other pre-treatment.
Please send in your comments on anything pertaining to fisheries to this column through observerfisheries@yahoo.com or text/call 7786848.
It has become a predominant consumable food among Gambian families. Therefore preservation of this major staple food needs to be giving special attention. The micro flora of living fish depends on the microbial contents of the water in which they live. Fish micro flora include bacteria such as Species of Pseudomonas, Alcaligenes, Vibrio, Serratia and Micrococcus. The level of contamination can increase with the type of processing and handling.
Fish are also susceptible to autolysis, oxidation and lipolysis in addition to microbial spoilage. Their preservation, therefore, should involve a combination of treatments. Evisceration should be done immediately after harvesting, to prevent the gut enzymes from becoming functional. Preservation of fish by chilling temperatures is said to be only a temporary method though freezing is recommended as the best way to preserve fish for a longer time. Freezing kills most organisms but not the psychrophiles and the spores.
Most of these survive freezing and grow during thawing. Fish preservation by radiation has been tried and found successful especially when used in combination with freezing. Salting and drying methods of fish preservation are other means of fish preservation in The Gambia.
Sodium chloride serves as a chemical preservative and binds the moisture. This may, however, not affect the halophiles which sometime cause discolouration during drying. Other chemicals used in fish preservation to retard microbial activity include sodium and potassium nitrite and nitrate, benzoate and sorbate.
A dip in antibiotic solutions has been tried and found successful but these days, it is not encouraged. The kind and rate of fish spoilage varies with a number of factors, such as the kind of fish, the condition of the fish, the level of contamination, the storage temperature and other pre-treatment.
Please send in your comments on anything pertaining to fisheries to this column through observerfisheries@yahoo.com or text/call 7786848.
Author: By Amadou Jallow
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