Once upon a time, there were four basic tastes: the old standbys of sweet, salty, sour, and bitter.
Then, a few years ago, things began to get more complicated. In 2009, umami — Japanese for “savory” — snagged the title of “fifth taste.” Since then, scientists have added a couple more to the list: oleogustus, or the taste of fat, and kokumi, a sort of hearty mouthfeel. Both have been billed as the “sixth taste,” though the title hasn’t really stuck for either one. But as Jessica Hamzelou recently reported in New Scientist, there’s now a new contender for the title: Carbs, it seems, may have a taste all their own.
“Every culture has a major source of complex carbohydrate. The idea that we can’t taste what we’re eating doesn’t make sense,” Juyun Lim, a food scientist at Oregon State University, told New Scientist. In a new study in the journal Chemical Senses, Lim and her colleagues attempted to isolate the taste of starchiness for the first time:
Her team tested this by giving a range of different carbohydrate solutions to volunteers — who it turned out were able to detect a starch-like taste in solutions that contained long or shorter carbohydrate chains. “They called the taste ‘starchy’,” says Lim. “Asians would say it was rice-like, while Caucasians described it as bread-like or pasta-like. It’s like eating flour.”
The volunteers could still make out this floury flavour when they were given a compound that blocks the receptors on the tongue for detecting sweet tastes. This suggests we can sense carbohydrates before they have been completely broken down into sugar molecules.
It’s a start, but starchiness still has a ways to go before it can join the ranks of umami and company. “Before any new flavors can be enshrined as primary tastes, they must meet a strict list of criteria,” Hamzelou wrote. “Tastes need to be recognizable, have their own set of tongue receptors, and trigger some kind of useful physiological response.” Lim and her colleagues haven’t yet identified the specific receptors that correspond to carbs, though they argue that they have the other two criteria covered. The study shows that starchiness is recognizable; its usefulness, meanwhile, comes from its signaling of a valuable energy source — it’s a flag that starchy foods will fuel the eater.
“I believe that’s why people prefer complex carbs,” Lim said. “Sugar tastes great in the short term, but if you’re offered chocolate and bread, you might eat a small amount of the chocolate, but you’d choose the bread in larger amounts.” Something to think about next time you’re slurping down a bowl of noodles — there’s a scientific reason they taste so good.