Final answer:
The characteristic fishy odor of non-fresh seafood is due to volatile amines released by bacteria acting on fish tissue, with trimethylamine being a key compound responsible for the smell. Bacterial fermentation is also used to produce fish sauce, and avoiding foreign bodies in food is essential for food safety.
Step-by-step explanation:
The characteristic fishy odor of seafood that is not fresh is primarily due to the action of bacteria on fish tissues, which releases volatile amines.
When seafood is no longer fresh, specific microorganisms break down compounds within the fish, producing amines such as trimethylamine, which is responsible for the fishy smell.
The presence of a fishy odor is most noticeable when 10% KOH is added, which raises the pH and liberates the amines, enhancing the odor.
Bacterial fermentation is also responsible for the production of fish sauce, a salty condiment, and the process of bacterial growth leading to oxygen depletion in aquatic systems due to excess nutrients is known as eutrophication.
It is worth mentioning that the practice of using lemon juice or vinegar on fish can help reduce fishy odors by neutralizing these volatile amines, turning them into less volatile ammonium salts.
Furthermore, it is crucial to be vigilant about food safety to prevent foodborne diseases, which can also be caused by the adulteration by foreign bodies, such as insects or mouse droppings, that contaminate food items.