The complicated recipe of ‘taste’

I love Indian food not only because I find them really delicious but also because they are so complex that a gifted writer could spin out a novel riding on the revelry of tastes dancing, cavorting inside one’s mouth. Palak paneer or any masala now comes to mind. In a movie entitled Today’s Special about a chef who was in an inner tug-o-war between his American dreams and his Indian roots, masala was presented as a dish that was emotionally calibrated by the chef’s soul – sifting and grinding a variety of spices – in heirloom bowls. Guess what? The science of taste is evolving to be as complex as how masala is made. 

As far back as could be remembered, we have always been taught that there were 4 fundamental tastes: sweet, sour, salty and bitter. Textbook portions on this would even have the tongue drawn with specific locations for each of this fundamental taste. “Fundamental” because scientists thought that the many flavors we experience is just a product of the many permutations of these 4 plus smell.

This was textbook knowledge for centuries and not even later discoveries that solidly revised this knowledge saw the textbooks change (makes you think we should really be careful about choosing who writes and corrects textbooks.) In 1909, a discovery on the fifth taste should have already bumped up the number of basic tastes to 5.  In the early 70’s, it was also proven that all the receptors for the tastes can be found all over the tongue and not only on specific parts.

It was in 2002 when the actual receptors in the tongue for umami, the fitth taste, was identified and published in the Oxford Journals. The paper included an acknowledgement that even as far back as 1908, Ikeda Kikunae, already discovered the molecular structure that evokes the fifth taste and published it in a Japanese science journal in 1909. “Umami” has been established and it had the scientific support to sit on the 5th throne in our sense of taste. 

But instead of appreciating the basis for this, the history of umami became tied with the myth about the harmful effects of MSG – the crystalized form of a compound that locks on to umami receptors. This widespread perception, that started and was perpetuated without solid evidence, could probably be held responsible for why the discovery could not find its way into textbooks. It was the gustatory equivalent of when Pluto was kicked out of the bucket we called “planets” but many just could not emotionally let the distant planet go.

Recently, Anthony Bourdain was able to say in one sweeping statement, the scientific truth about MSG, that scientists have been stating and restating in vain for decades. That based on studies on humans, MSG is not a harmful chemical, it’s chemical composition is the same as that component in cheese, mushrooms, meats, seaweed that elicit the fifth fundamental taste: umami.

And I have news for those who still stay away from recognizing “umami” as the 5th taste: the race for the 6th is on. And so far, there are two contending candidates: “fatty” and “starchy”.

And that is not the only thing that has not been as neat as we want it to be in the way we have always understood “taste”. It has something to do with the bigger pan called “flavor” and how it has been so often cited that it is 75-95% smell, depending on who says it.  A study that tackled this just could not find basis for these percentages because “flavor” is a term that could not be defined on common ground. As far as evidence could support, the scientists could say that flavor is really dominated by smell but as far as the extent goes, they will not commit to any.

So what do we have now? We have 5 fundamental tastes with receptors all over the tongue conspiring with aromas, which make up for most of the flavor we experience, but with the sixth taste still a toss between two nominees: starchy and fatty. Is this where we are at?

Not quite. All the while that taste scientists have zeroed in on the tongue as the main organ that detects tastes, the real connoisseur is the brain. It has recently been found that we actually taste with our brain. They found this out because when they silenced or activated brain cells in mice for specific tastes like “salty” and “bitter”, those mice behaved only according to what they did to the brain cells and not what the mice ate. For example, when the scientists artificially activated a brain cell for “sweet”, the mice reacted as if it tasted “sweet” even if it only had plain water.

This does not mean that the tongue is just a decoy. The tongue houses the receptors that recognizes the chemicals in what we taste but they transmit this to our brain which figures out the taste and decides to tell us what we are tasting – sweet, salty, sour, bitter or umami.

That is so far, what this recipe for understanding the science of taste, looks so far. It is far more interesting now than the ancient 4-throned tongue. Savor it as it the recipe may soon change again. – Rappler.com