Oh, I'm sure it's detected by the detection apparatus, then filtered. Just like I know that my eyes are picking up light reflected off my nose just like they are picking up light reflected off my keyboard, but I don't see my nose. I also don't hear the blood flow that vibrates my eardrums.
haha
well... i did a quick dig... experiments have been done... first of all rats ofc
They show that our saliva changes and on top (a real surprise) is that some changes are deliberately done to experience a different taste.
Roughly 99.5 percent of human saliva is water, but the rest is an important chemical mixture of compounds that help to break food down and protect our teeth – and even to taste food itself. This last part is key here.
Proteins released by our salivary glands are thought to bind to flavour compounds in food, and also to taste receptor cells in your mouth, which is why Running calls the fluid the "chemical media of the mouth".
The thing is, those proteins aren't static. Previous research with rats demonstrated that when the animals were fed a diet of bitter food, the expression of these flavour proteins in the rodents' saliva was altered.
"Saliva modifies flavour, which in turn modifies dietary choices."
https://www.sciencealert.com/you-can-modify-your-saliva-to-make-things-taste-better-study-shows