Umami binds to receptors to release the flavour that we perceive in our brains. However, that receptor can be closed even more to enhance the depth and duration of the effect, with nucleotides.
Glutamate
Umami comes from glutamate, which generally exists in fermented food.
That said, the highest concentration of umami comes from kombu, as much as 1000-3000mg/kg of kombu.
Nucleotides
These are the by-products of ATP consumption. Therefore, animals, and especially sea creatures are rich in them.
There are two classes of nucleotides, IMP and GMP.
Nucleotide Classes | Umami Potential | Umami duration |
---|---|---|
IMP | 8x | 33%+ |
GMP | 30x |
Most food have IMP, but things like dried shiitake mushrooms have high levels in both GMP and glutamate.