When it comes to the science of taste, describing the mouthfeel of a drink or snack isn't enough. Fat, it turns out, is especially tough to nail down. According to Edible Geography, researchers first discovered a taste receptor specifically tuned to fat only last year. We mostly detect fat through texture, which makes it hard for food companies to formulate studies for fat-free or low fat foods.
If you've ever eaten a bite of fat-free ice cream and thought it tasted wrong, somehow, here's your answer: When you rub your tongue against the roof of your mouth the papillae should feel ever-so-slightly rough, but when your tongue is coated with fat from milk or cheese or something else, it's smooth and friction free.
Now, scientist George A. Van Aken has come up with an alternative that isn't susceptible to the descriptive power of human taste testers. Edible Geography explains the concept behind Van Aken's "acoustic tribology":
Van Aken took a tiny contact microphone, packed it in polyethylene to keep it dry, and secured it behind a test subject’s upper front incisor teeth in order to record the acoustic signal produced by the varying vibrations of their papillae as their tongue rubbed against their palate.
Instead of relying on tasters to describe what their tongue is feeling, scientists can listen to that sensation. And you can actually listen to the difference yourself below:
First, here's the sound of someone rubbing their tongue against their palate after drinking black coffee.
Second, here's the sound of someone doing the same, but after drinking coffee with cream. Notice the difference?
Food studies rely on a combination of human testers and machine tests using synthetic tongues (or pig tongues) and a fatty substance to provide qualitative and quantitative data. If Van Aken's acoustic tribology works out, it could possibly replace those machine tests, or at least make the human tests a whole lot more reliable. Once we figure out exactly how we experience the sensation of fat, we can better recreate it, opening the door to weirder, tastier engineered food experiences.