How do we really taste? Are the five “common” tastes of sugary, salty, bitter and sour, plus the Japanese researched savory taste of umami, all that’s required to give food – and much of our life – flavor?
Researchers at Oregon State think not. They’ve identified the villain and pleasure of dieters almost everywhere, carbohydrates, common “carbs,” as possessing their own separate apparatus of taste. And that may tell us a lot not just about how we taste, but about how the brain appreciates taste.
The usual group of volunteers were given a not very luscious preparation of glucose oligomers (7-14 sugar molecules combined together) versus those with an average polymerization of 44. Interestingly, they could taste something separate in the small, carbohydrate oligomers, the sort that might be created by mashing food with your teeth aided by enzymes in the mouth, but could separately taste the bigger polymers.
And then the fun began. They were next given the chemical lactisole, which blocks our ability to taste sugary foods. Now, as predicted, they could not taste sugary stuff. But the oligomers? People described the taste as “starchy,” with Asians claiming it was something like rice, Caucasians something like pasta or bread, according to Juyun Lim, who headed the study group. That’s new.
For a very long time, researchers have regarded carbohydrates as pure polymers of sugar. Eat a carb, eat a sugar, they would argue. And not just from the standpoint of taste, but from that of diet. Let the gut digest a starch, and sugar-sugar-sugar is the result.
But does that make carbohydrates a new taste? Not so fast. To officially make something a separate “taste,” like umami, you need to identify its receptors on the tongue. That’s not been found for carbohydrates. Tastes also require separate cognitive brain recognition, and must create a specific physiological response.
Can we identify physiological responses when we eat carbohydrates? Sure. Ever eat a pizza?
Right now there are plenty of other contenders for new tastes. One is the taste of blood – apparently it’s not just for vampires anymore. But is taste merely about taste receptors?
A Matter of Smell
One awful result of brain injury is the loss of the sense of smell. When people lose much of their sense of smell, their complaint is usually not that they can’t smell things – it’s that they can’t taste.
Some researchers argue that the large majority of what we call “taste” in foods is actually smell.
The olfactory nerves snake down the brain into our nose. Stuff our nose with allergic reactions, and we can’t smell. Food tastes “funny.” Wait a while and things can change.
Unlike many nerve cells, olfactory nerves regrow themselves from buds in a matter of weeks. Kill the buds, kill the cells. Hence, no smell, and no taste.
Which tells us a lot about sensation.
The Brain Constructor
We sense seeing is reality. We perceive through our senses. Yet our senses are combinatory brain tricks.
Just as tens of thousands of light packet impressions are sent up to different parts of the brain to eventually get processed into the “reality” of sight, so does taste come out of an amalgam of receptors.
Some are the famous ones – sugary and salty, a select category that carbohydrates may now join. Yet many of us crave and rapidly “taste” fat – which has no separate taste receptor. To feel the fatty pleasure of pizza we rely on our smell receptors, our sense of texture, and yes, our eyes.
For food and taste result from endless combinations of different sensors and the extraordinarily varied ways they are processed in the brain. Processes that are so heavily inflected by culture that one man’s meat, say the ineffable taste of Scottish haggis, is felt by some as unpleasant poison. Which is why the favored national dishes of one country may be all but unpalatable in the civilization next door.
Even if carbohydrate does not attain status as a separate “taste,” the rest of us are quite conditioned to the taste of bread, and pasta, and rice. We love the stuff. We crave. In our minds, we can “taste” them.
For the information system that is the body creates not just pleasure and pain, but the very flavor of life itself. Flavors that will shift second by second, changing with context, format, social environment, pretty much anything that we can consciously feel and express.
The actual numbers of new tastes is far more than five or six. It’s closer to infinity – and that’s true for most of the seven and quarter billion individuals on the planet.
It’s not the tongue that makes food really tasty. It’s the brain. Ask any chef worth his salt – imagination is the only real limit of taste.