FISH PROCESSING, SPOILAGE AND PRESERVATION

Fish processing is the act of changing the natural form of fish in order to extent it's shelf life. Processing is very necessary because all fish have bacteria in their intenstines; immediately they die these bacteria begin to multiply,causing decay of the fish. That is why the first thing to do as soon as fish is killed, is to remove the intestines. In the high ambient temperature of the tropics, fish will spoil within 12 hours. Good fishing method is therefore advised to avoid injuring the fish and cooling them with ice on-board (if they are caugth in natural water bodies) will help to increase the shelf life of fresh fish.

HOW TO KNOW SPOILED FISH
(A) The pupils (of the eyes) become red and milky instead of being clear.
(B) The gills which are supposed to be bright red are rather dark red with slime on them.
(C) It may have rotten fish smell.
(D) The flesh becomes soft with traces of brown blood instead of the normal firm flesh and red blood characteristics of good frsh fish.

THE DIFFERENT KINDS OF SPOILAGE IN FISH AREA;
FAT OXIDATION: This is a chemical reaction which takes place between the fat in the flesh and oxygen in the air. The fish acquires a rancid smell and taste. This happens when fatty fish is exposed for a long tme to air during smoking or drying. It is therefore advisable to smoke and dry only less fatty fish.
MICROBIOLOGICAL SPOILAGE: This kind of spoilage is caused by bacteria on fiish surface and those in the intestines and starts quickly in fish because of their non-acidic nature.

AUTOLYTIC SPOILAGE: This type of spoilage happens within the fish and caused by enzymes inside fish which starts breaking down compounds into smaller parts when fish dies. Some hours after dealth of fish, the flesh stiffens and becomes turgid. This is called ''rigor mortis''. After that, enzymatic reactions (autolysis) make the fesh softer again. The action of the enzymes on the flesh affects the texture, smell and taste of the fish.
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