By Juyun Lim | Terra Blog | Posted August 24, 2012
Did you ever wonder why so many people are attracted to junk food? Why ice cream, french fries and soda pop so often win out over brown rice and broccoli?
It’s not actually a conspiracy by fast-food companies to bewitch people into eating things that aren’t good for them. Well, not completely. It’s largely due to an evolutionary instinct that was useful when people wondered around in the woods searching for food, 100,000 years ago.
In the distant past, we heavily depended on our senses to make a decision of what to eat and what not to eat. In nature, foods that were sweet were almost always safe to eat and were good for us; they made our hunger go away. Foods that smelled odd or tasted bitter or sour usually meant they were potentially toxic or spoiled — and less safe to eat. That was pretty useful information for a person who lived in a hunting and gathering era and wanted to avoid starving or getting poisoned.
In the modern environment where we buy food in supermarkets or restaurants, those same survival instincts are serving only to make us obese and chronically ill.
We have a routine choice of what to eat and how much to eat, and with depressing consistency, we often choose the wrong ones, the ones that carry lots of macronutrients like carbohydrates, sodium and fats. Because foods that are high in sugars, sodium and fats are readily palatable to us, we eat them too much!
The science of flavor – how we taste and smell it, why we like or don’t like it – is still in its infancy. In a series of recent publications in Chemical Senses, we learned that the “congruency” of the different components of flavor is a key to how we perceive the overall flavor of foods. Flavor components that seem to “go” together, like vanillin and sugar, are perceived as a unified sensation that seems to come from the mouth. And barely detectable vanillin becomes so much stronger when sugar is added to vanilla-flavored drink or custard, making it even more palatable.
Actually, that’s our brain playing a trick on us. Vanillin, the primary component of the vanilla bean, has no sweet taste at all, it’s only a smell. And the pleasant sensation is coming not from your mouth but from the nose, through the passageway between the back of the mouth and the back of the nose.
Then, the final decision about what something tastes like is made in neither the mouth nor nose. It’s in your brain, where sensory signals are processed and “bind” as a unified, harmonious perception, like “vanilla custard.” That data gets relayed back to your mouth where you believe the sensations are coming from.
There’s just a lot we don’t know about exactly how people perceive flavor and how it plays a role in food choice and selection. When we learn more about these processes, it might be possible to more effectively teach our palates to like what is good for us. In other words, to really enjoy eating broccoli just as much as eating an ice cream sundae.
The science of flavor is complicated. Some of the players include taste such as sweet, sour, salty, bitter and savory, which is detected solely on the tongue; smell such as vanilla and basil, which is exclusively detected in the nose; and somesthesis, which includes things like touch (the texture of Crème brûlée), temperature (the warmth of soup), and irritation (the burn of hot peppers). All of these sensations provide data to the brain, and it makes the final call.
If you really think you can “taste” everything in your mouth, take a sip of your favorite drink while pinching your nose, and see what it tastes like. Don’t recognize it? Open your nose, and the familiar taste will reveal itself.
The perception of flavor is partly instinct but also a learned behavior. And because it can be learned, there are probably ways that we can teach it. Hardly anyone really likes the bitter taste of coffee the first time they drink it. Since the caffeine in coffee makes them feel energized, however, they learn to like its flavor.
We may never completely lose our desire for ice cream, and we don’t have to. But science may help us find a way to deal a little better with our foods and our dietary choices.
Juyun Lim is an assistant professor in the Department of Food Science and Technology at Oregon State University. She’s an expert on human sensory perception of food, and sensory and consumer testing methodology. This article appeared in the Huffington Post on June 12, 2012.