Locked in the chain it has no umami; MSG is that cut, as powder.
Full mechanism, in text
Glutamate is already in your food
1 · In the gut it is the same ion as in a tomato
, the sodium salt of glutamic acid, dissociates into free glutamate and sodium once in the body; in the gut it is the same molecule as tomato glutamate.
2 · Locked in protein has no umami; free does
Glutamate locked in a protein chain has no umami; only free glutamate, already off the chain, gives the umami the tongue tastes.Glutamate sits in food two ways. Locked in a protein chain it has no umami and is not absorbed as-is — enzymes have to cut it free. Every bit of umami the tongue tastes comes from the free form.
3 · Fermentation pre-cuts; MSG is that step as powder
Parmesan aging and soy-sauce fermentation free glutamate from the chain in advance, and industry makes the same way, with microbes producing free glutamate.Parmesan aging and soy-sauce fermentation pre-cut glutamate off the chain. Industry makes the same way: microbes produce free glutamate, then bind it to sodium. MSG is not a chemical substitute. It is the step that makes cheese and soy sauce savory, lifted out as powder.
4 · Brain glutamate is made on site, not from the meal
Brain glutamate is made and recycled on site by neurons and astrocytes, and the barrier mainly moves it out into the blood, so a meal does not steer it.Neurons and nearby astrocytes synthesize it on site and recycle it on site. Barrier transporters mainly move glutamate from brain into blood, not the other way. Concentration itself is the signal, so the system does not let a meal steer it.