Shiitake mushrooms produce an enzyme that gets supercharged by salt, creating more savory umami flavor. The enzyme glutaminase becomes up to 32 times more active when salt is present, converting an amino acid called glutamine into the molecule responsible for umami taste at normal cooking salt levels (1-2%). The stem of the mushroom showed even higher activity than the cap and when researchers combined shiitake with garlic (which is rich in glutamine), it produced 18 times more glutamic acid than shiitake alone. This natural method could help reduce the need for artificial flavor additives.