Bacteria establish themselves on the outer and inner surfaces of the live fish (gills, skin, gastro intestinal tract). The poikilotherm nature of fish allows bacteria with a broad temperature range to grow. When a fish dies, the bacteria already present in the fish attack the flesh and result in the formation of undesirable products.
Two of the most common types of microbes that can contaminate raw fish include Salmonella and Vibrio vulnificus.
Fish, mollusks, and crustaceans can acquire pathogens from various sources. All seafood can be susceptible to surface or tissue contamination originating from the marine environment.
Contamination in fish can be started from when it kept in ice due to low quality of ice or storage condition. At the time of transporting fish from fishing place to selling market, contamination may also occur if the temperature is not maintained.
The bacteria cause fish spoilage by the following means:
*Reducing of trimethylamine oxide into trimethylamine produces an offensive odor.
*Degradation of amino acid to primary amines: It can cause food poisoning.
Fish products with high salt contents may spoil due to growth of halophilic bacteria (salted fish) or growth of anaerobic bacteria and yeasts (barrel salted fish).
Fish spoilage due to microbial growth
A gill is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide.
An animal that regulates its internal body temperature throughout a wide range of temperatures, frequently in response to changes in the ambient temperature is known as poikilotherms.
