Final answer:
Phosphatidylcholine is the phospholipid in fish fat which contributes to its characteristic fishy smell, with the smell becoming exacerbated through the process of oxidation. Acids can reduce this odor by neutralizing volatile amines in the fish.
Step-by-step explanation:
The phospholipid responsible for the fishy smell of fish, which can be affected by acid and oxidation, is known as phosphatidylcholine. This class of lipids plays a crucial role in the structure of biological membranes and contains fatty acids that can undergo oxidation, leading to the unpleasant smell. Oxidation of unsaturated fatty acids at the double bonds, especially when fats are exposed to atmospheric moisture and temperature, leads to rancidity, producing compounds like hydrogen peroxide that give off a bad odor and taste. The use of acids such as lemon juice or vinegar on fish can neutralize volatile amines in the fish, producing involatile ammonium salts and mitigating the fishy smell. A phospholipid molecule typically has two fatty acids and a modified phosphate group attached to a glycerol backbone.