Chemoreceptors

Chemoreceptors in the taste buds of your tongue require a liquid medium in order for the flavors to bind into the receptor molecules.

If you don't have liquid, you won't see results. Now, technically you can use water for this purpose rather than saliva. However, saliva contains amylase, an enzyme that acts on sugars and other carbohydrates, so without saliva, sweet and starchy foods may taste different from what you expect.