Whenever acetic acid or ethyl acetate is applied, chemistry teachers often introduce the esterification reaction of acetic acid as an example of roasted fish.
Produces ethyl acetate with an aromatic odor!
Nothing wrong with that!
But. Is a fragrant braised fish fragrant because of ethyl acetate? Or is it because the fishy smell has been removed?!
So here's the problem!
Why do fish have such a big fishy smell?
The fishy taste is mainly related to the fish itself, we all know that the taste of fish is originally very delicious, and this umami taste is mainly derived from the oxide trimethylamine contained in the fish body.
However, this oxidized trimethylamine is very unstable and is particularly susceptible to reduction to trimethylamine with a fishy taste.
From the perspective of the physiological changes of the fish, after the life activity of the fish is stopped, the oxidation of trimethylamine in the body will continue to be reduced to trimethylamine, so that the fish will produce a fishy taste. As the freshness of the fish continues to decrease, the trimethylamine component in the body also increases, and the fishy taste of the fish is very prominent. This also explains why when we kill fish, the fish can be very fishy.
The causes of fishy odor are both factors and influences of the environment. For example, freshwater fish generally grow in ponds, rivers, lakes, and these places have more humus, which is suitable for microbial reproduction and growth. Bacteria with an earthy odor attach to plankton such as diatoms and cyanobacteria, as well as some aquatic plants, which freshwater fish ingest through the food chain and then enter muscles, bloodstream, and tissue cells, producing the earthy smell we smell.
Of course, improper storage is also another factor that leads to the fishy odor, when we do not store the inactive fish properly, the fish will produce fat oxidation and amino acid degradation in the process of spoilage, thereby increasing the fishy smell of the fish. Common fishy substances are mainly derived from aldehydes, in addition to alcohols, ketones and furans, such as aminovaleric acid, aminovaleraldehyde and hexahydropyridine in the mucus on the surface of fish, earth odorin in water, 2-methylisocarbohydrin, fish body decay degradation products dimethylamine, trimethylamine and other substances.
When grilling fish, what is the purpose of adding a small amount of wine, vinegar and ginger?
Wine has the effect of promoting protein coagulation, and if the protein is not decomposed, trimethylamine will not be formed. Adding vinegar can turn trimethylamine into a odorless salt; as for ginger, it is a synthesis of alcohols and ketones, both of which have a relatively strong ability to remove fishy odors. Therefore, the main role of wine and vinegar is to remove the fishy smell of fish, not to esterification reactions.