Canadian Pizza Magazine

Features In the Kitchen Ingredients
Tech Slices: Taste – Front and Centre


February 28, 2008
By Bob McDougall

Topics

That’s right – taste is front and centre this month… and on top and to each side!

That’s right – taste is front and centre this month… and on top and to each side!

Most of us learned in our school years that different parts of the human tongue react to the four main components of all tastes. According to the “scientists,” we were all told sweet is sensed on the tip and front of the tongue, salt on the front sides, sour on the rear sides and that yucky old bitter on the back top of the tongue.

Like me, you can probably recall a very official-looking diagram showing all this detail in glorious colour. Only one problem … it’s wrong.

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Many of us who figured we must have been doing the experiment incorrectly, because we could sense the sugar away back on the tongue, or the tangy acidity of the citric acid on the tip can now put our minds to rest.

So then where do we sense tastes, anyhow? Tasting, or, scientifically, “degustation,” is indeed based on the tongue and in adjacent throat areas. On the tongue itself, only the middle top area is largely insensitive to tastes. The roughly 5,000 tiny protruding taste “buds” have exteriors sensitive to certain triggers when in contact with them. There are different types, which react to often more than one possible taste. There are salt sensitive taste buds everywhere, but others that detect both sour and bitter are more grouped. There are also “sour only,” and sweet sensing buds that also seem to sense other things.

There are also about half again the tongue’s number of taste buds found around the mouth cavity and even part way down the throat. All the sensitive areas have varying numbers of each type; so will react to all the tastes, though there is indeed a variation pattern in sensitivity from spot to spot.

The actual sensing cells replace themselves every 10 days or so, ensuring that we can get past the effects of spice or heat damage to the tongue’s sensitivity. There’s no end to the further details available on the web if you’re still interested in the science of taste, but let’s talk about the “four tastes” themselves …  and by the way there are actually five. Or maybe six.

In the case of sour tastes, the trigger for taste is the freely dissolved component common to all acids, called “hydrogen ion.” Thus, the acid notes of all sour foods like vinegar, sour pickles and even some candies have a common similar character. Though other aromas, compounds and even temperatures may modify the basic tanginess, it’s almost always easy to spot. Scientists theorize that since sour tastes can indicate spoilage in food, the reason for this taste existing may be defensive. Unfortunately for us, sourness is the only “clear-cut” taste in the bunch.

Saltiness, normally associated with good ol’ sodium chloride (table salt), can also be produced by other similar chemicals, although almost all have objectionable differences we can taste. Salt sensing on the tongue is the most uniform of all tastes. It makes sense that we would be very acute in sensing foreign tastes in something as essential for life as is salt, but whose primary characteristic of “saltiness” can be mimicked by many other, potentially poisonous natural compounds. In the science of food, it makes undetectable salt reduction in food using salt substitutes a very difficult exercise indeed.

Sweet, sweet, sweet – many people’s favourite. Molecules that stimulate the same buds as the basic sugar found in all living things, called glucose or dextrose, trigger sweetness. Many other sugars mimic this shape and so are sensed as sweet. Artificial sweeteners also trigger the same taste buds, but the shapes of their structures are often very different and their sweetness strength thousands of times greater. However, they may also overlap and trigger other taste sensations in varying degrees, causing them to taste subtly different than sugars.  Again, this can cause real problems when food scientists try to sweeten without sugar.

Bitterness appears to be very complex. It had been thought to be sensed with the same taste buds as sourness. Recent studies have indicated the same ones as sweetness may also sense it, as well. Since few people actually like bitter foods, why have several ways to sense this taste? Again, many bitter foods or substances are quite harmful, at least in larger amounts. Many unpleasant plants and even most dangerous mushrooms are quite bitter to the taste. Sensing bitterness may again be a “last chance to spit it out” defence against swallowing them. In the realm of food, bitter extracts have been used for centuries to stimulate saliva flow and to awaken the appetite – and are most common as the slightly bitter but refreshing note in many types of beer.

Taste number five is a relative newcomer to study, having only been generally accepted as “real” at an
international conference in 1990. It is commonly known by its Japanese name “umami,” translated as “richness” or “deliciousness.” Think of what a bit of soya sauce can do for the flavour of a fried rice dish, and you have a good idea of what “umami” is. The flavour of ingredients providing umami in a food is often described as “meaty,” “brothy” or “savoury.” It is sensed by a separate group of cells in the taste buds.

As early as 2500 BC in the Mediterranean area, a pickled fish sauce called “garum” was used to provide umami to food. The much-maligned ingredient MSG is considered to add pure chemical umami, but almost any protein high in certain of its building blocks or amino acids, will add umami. This can be especially strong if they are partially fermented, dry cooked or broken down.

Those of us who like gravy made from pan drippings, cured pepperoni, seared steak, well-browned sausage, roasted vegetables and such foods are real lovers of umami. An ingredient providing umami can make the difference between an OK pizza and a delicious one.

One of the reasons that pizza dough allowed to rest overnight before stretching and use can taste so darn good is due to the death of some of the yeast – which releases natural flavour chemicals that provide – umami.

So about number six – that depends on where you are. In the west, and parts of the Orient, it is typically considered to be “astringency.” That “pucker up” taste found in green bananas, or provided by the tannins in really young red wine, that seems to dry up your mouth or make your teeth feel chalky. Perhaps you have found it in fresh spinach or radicchio leaves?

Well, so much for that neat, simple diagram of the tongue. Even at the level of basic sensory study, things are pretty complicated. Once we want to appeal to real people – things can and do get even more varied by culture, background and even genetics.

Despite such groupings, however, taste is as personal as fingerprints.In parts of Southeast Asia, the umami fullness taste may be considered to be the sixth taste, with the fifth being “pungency” or spiciness. In other areas the astringent may be combined with umami fullness. It’s a world of diversity out there, and taste is just as complex.

Whatever you make of tastes, remember that tastes + aromas + food environment (moistness, temperature, dryness, texture, etc.) = flavour. And flavour is what we all are after when we apply the science of food to perfecting the art of pizza.•