Guardian Weekend – Part of a series of 6 articles on taste and cooking with co-author Peter Barham

Around a quarter of the population are supertasters – people who are extra-sensitive to bitter tastes in food. Of the supertasters, two-thirds are women.

Scientists check for supertasters by measuring their ability to detect the extremely bitter chemical phenylthiocarbamide. That’s not a material that you are likely to have in your kitchen, but you can do something similar by tasting very weak solutions of potassium chloride (“sodium-free” salt substitute) or saccharin in water. If they both seem bitter, then you are probably a supertaster.

Of the five basic tastes (bitter, sweet, salt, sour and umami), bitter is the one that puts you off eating the food. It’s nature’s way of warning you, and other predatory animals, off. If a fruit tastes bitter it is probably poisonous. “Don’t touch me” is the message “and we’ll both be better off.”

Man, though, has learned to enjoy bitter tastes at low levels. Some foods, such as beer, are even deliberately made bitter (before you question the identification of beer as a food, you should know that one of us is Australian, and thus naturally regards beer as a food). Dishes such as beer casseroles exploit the bitterness as an essential part of an attractive taste combination.

We detect bitterness (as we also detect sweetness) through the little bumps on our tongues called papillae. You can see these bumps if you look closely at your tongue in a mirror. Scientists have identified three types (called fungiform, foliate and vallate, words that describe their shapes). The three types reside respectively on the top, the sides and the back of our tongues.

Inside the papillae are the actual taste buds – between one and fifteen for each papilla. Tiny food molecules reach the taste buds through holes in the surface of the papilla called taste pores. The taste buds contain receptors, sites where molecules that produce sensations of bitterness or sweetness can attach. When they do so, the receptor sends an electrical signal to the brain that says “Hoy, I’ve caught one!” The brain responds by saying “I now have a sensation of bitterness (or sweetness).” In the end, we taste with our brain, not our tongue.

Receptors for both bitter and sweet tastes are scattered all over the tongue, and even in the throat and the top and bottom of the oesophagus (the tube that leads to the stomach). There is some truth in the popular idea that sweetness is most strongly detected at the tip of the tongue and bitterness at the back (try drinking lemonade or tonic water, and see where the taste on your tongue is strongest), but there is great individual variation.

Supertasters actually have very organised tongues, with tightly clustered papillae surrounded by an unusual ring structure. You can check for these rings on your own tongue by wetting the tip with a blue food colouring agent, and having a friend (obviously an intimate one) use a torch and magnifying glass to count the pinkish unstained rings that show up against the blue stained tongue.

Whether you are a supertaster or not, the degree of bitterness that you detect in your food is going to be influenced by what else is there. The chef’s art is not to add so much of this and so much of that taste and flavour, but to produce a combination that appeals to the palate. That combination need not be constant through a dish, and probably shouldn’t be. It is the progression of tastes and flavours, as much as the individual tastes and flavours themselves, that distinguishes the product of a great, as opposed to an ordinary, chef.

If a chef gets the progression wrong, disaster can result. It is a mistake, for example, to follow one bitter food by another, since the first one may saturate the receptors, wiping out the flavour of the second. You can test this for yourself by drinking tonic water before eating dark chocolate. The tasty bitterness of the chocolate will be wiped out, leaving only the taste of wax.

You don’t even need one bitter food to wipe out the bitter taste of another. Salty and bitter tastes, for example, can interact in an unexpected way. A group of us found this in Erice with salt and tonic water. The tonic water has the bitterness of quinine, but by licking a little salt first the bitterness of a subsequent drink of tonic water was largely abolished.

The chef uses such taste combinations in subtle ways to enhance your enjoyment of your food. Try out some of Jeremy Lee’s recipes, and find how you don’t need to be a supertaster to be a supercook.

© This article is copyright Len Fisher. Please email Len Fisher to seek permission to reproduce part or all of the above article.

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