I'm thinking of something like an asthma inhaler, but you don't inhale and instead of medicine being ejected when activated a fine powder of concentrated flavor comes out. The powder flavors your saliva for a few seconds to a minute. And, since rumor has it that 50% of taste is smell, it a complimentary scent will also be exposed when activating.

Tasty flavor treat with minimal or possible even 0 calories.