Flavour enhancers [closed]

In a way, fat and acid are. If you already consider salt,sugar,glutamates - anything that influences TASTE directly but not flavour/aroma and is not bitter (given recent research, we can taste more than one kind of bitter, which fits in there interestingly...)

Glutamic acid in other forms than its sodium salt (to be found in a lot of ingredients).

In industrially made products, inosinate and guanylate compounds are frequently used. For example, japanese kare roux cubes, and golden mountain soy sauce contain them. Such compounds are frequently non vegetarian unless stated.

Recently, some substances have been isolated and marketed that purport to enhance the newly found "kokumi" sensation.

There are certain chemicals marketed that REDUCE the sensation of sweetness or saltiness, or bind rancid-tasting molecules into an inert form (pea dextrin).