Humans may have sixth taste sensation in addition to basic five

Other than five basic tastes that include sweet, sour, bitter, salty and umami, humans may also have a sixth taste sensation, researchers say.

Yet for all one’s sophistication in the kitchen, the scientific understanding of how an individual tastes food could still use some time in the oven. Dating back to ancient Greece and China, the sensation of taste has historically been described as a combination of a handful of distinct perceptions, Live Science reported.

Western food research, for example, has long been dominated by the four ‘basic tastes’ of sweet, bitter, sour and salty.

In recent decades, however, molecular biology and other modern sciences have dashed this tidy paradigm. For example, Western science now recognizes the East’s umami (savoury) as a basic taste. But even the age-old concept of basic tastes is starting to crumble.

“There is no accepted definition of a basic taste,” said Michael Tordoff, a behavioural geneticist at the Monell Chemical Senses Center in Philadelphia. “The rules are changing as we speak.”
Some taste sensations vying for a place at the table as a sixth basic taste include calcium, kokumi, piquance, coolness, metallicity, fat and carbon dioxide.

The element calcium is critical in our bodies for muscle contraction, cellular communication and bone growth. Being able to sense it in our chow, therefore, would seem like a handy tool for survival.

Calcium clearly has a taste, however, and counter intuitively most mice (and humans) don't like it. People have described it as sort of bitter and chalky – even at very low concentrations.
The calcium receptor might also have something to do with an unrelated sixth-taste candidate called kokumi, which translates as ‘mouthfulness’ and ‘heartiness.’

Kokumi has been promulgated by researchers from the same Japanese food company, Ajinomoto, who helped convince the taste world of the fifth basic taste, umami, a decade ago.

Spicy-food lovers delight in that burn they feel on their tongues from peppers. Some Asian cultures consider this sensation a basic taste, known in English as piquance (from a French word). Historically, however, food scientists have not classified this undeniable oral sensation as a taste.

At the opposite end of taste sensation from piquance’s peppers is that minty and fresh sensation from peppermint or menthol. Still, there is an argument that temperature sensation, both in the genuine sense and in the confused-brain phenomenon of piquance and coolness, deserves to be in the pantheon of basic tastes.

Metallicity is yet another controversial ‘taste’ is our registering of metals, such as gold and silver, in the oral cavity.

Although usually tasteless, such garnishes are sometimes reported as having a distinctive flavour.