Umami. The unknown flavour maker
Slowly this mixture then begins to disintegrate. The salt mixes with the fermentation and the resulting liquid is drained off. This liquid is mixed with the fish again and the process continues. It is repeated until the fish sauce is ready. The whole process takes at least half a year. As with wine, longer fermentation increases the quality.
Important is the formation of glutamates, flavour enhancing amino acids, the building blocks of proteins. They are naturally found in old cheese, mother's milk, tomatoes and sardines, and provide a savoury taste. That savoury taste is called umami, after the Japanese word for delicious or savoury.