Brightness, not sweetness, is doing most of the work in that zero-sugar lemon mint drink. Citric and other lemon acids hammer sour-sensitive taste receptors on the tongue, while their low pH shifts saliva proteins and makes every tiny ion exchange feel more intense than the ingredient list suggests.
More radical is the quiet assist from mint. Menthol, the key cooling agent, binds to TRPM8 ion channels in sensory neurons, the same hardware that reports real temperature drops to the brain, so a chemical trick starts to feel like physical relief. That trigeminal nerve activation layers a cool, clean signal on top of sour brightness, and the brain tends to interpret such structured input as complete flavor, even when sucrose never shows up.
The drink, then, wins by distraction. Sour stimulation drives salivation, literally flooding volatile lemon and mint molecules across olfactory receptors in the nose, while the cooling tingle adds mouthfeel usually delivered by sugar weight. Between gustatory signaling, olfaction and trigeminal input, the neural pattern looks full, lively, finished. The label stays at zero added sugar.
