Bitterness blocking

Taste is highly subjective.  You may like rhubarb, which I regard as mutated celery.  I, on the other hand, like haggis, whereas organ meats ground up with oatmeal and boiled in a sheep’s stomach may not appeal to you.  And so on.

And yet soon we may all be able to agree on what we like to a greater degree than ever before, as scientists work with new knowledge of the genes involved in the sense of taste to create compounds that can block the unpleasant tastes of some foods.

Before I get to the new developments, however, a brief primer on taste itself is in order.

No matter what our personal preferences, our tongues all respond to the same five tastes.

The four best known of these are sweet, bitter, salty and sour, but recently more scientists are accepting the fact that there is a fifth basic taste, umami, a Japanese word that can be roughly translated as “savory.” Umami is the taste of glutamate, an amino acid found in protein-rich foods such as cheese, meat, fish and human milk, as well as asparagus, tomatoes–and, of course, the flavor enhancer monosodium glutamate, or MSG.

Saltiness is produced primarily by sodium chloride, sourness by acids, and sweetness mainly by sucrose. Many compounds taste bitter; but then, we’re a thousand times better at detecting bitterness than any of the other basic tastes, probably because most natural poisons taste bitter. We prefer things that are sweet, which also makes sense; mother’s milk, after all, is sweet, as are most ripe fruits and vegetables.

The food-processing industry, knowing that people don’t like bitterness and sourness, uses a lot of fat, salt and sugar to mask these unpleasant flavors.  This has obvious health implications.  And our dislike of bitter things also has another health implication:  some life-saving drugs are very bitter–literally hard to swallow.  And adding a spoonful of sugar isn’t always enough to make the medicine go down.

Now there’s a new approach, an offshoot of the discovery, just three years ago, of the genes involved in the sense of taste.

We know that each taste bud is like a tiny computer that analyzes, codes and sends to the brain inputs from as many as 100 sensory cells. Genes tell cells what proteins to make; the genes involved in taste sensations tell the taste cells to make special proteins on their surface called receptors. When a specific type of tasty molecule in a food–a sodium chloride molecule, for instance–comes in contact with the proper receptor, the receptor binds onto that molecule. That triggers a complex process that leads to excitation of the nerve fibers connected to the taste cell and ends with our brains going, “Mmmm, salty!”

Last month, Linguagen Corp., a company in New Jersey, received a U.S. patent for the first chemical known to inhibit the taste of bitterness by altering the human sense of taste (as opposed to simply covering up the bitterness).

The chemical is called adenosine monophosphate (AMP).  It’s a naturally occurring substance made up of nucleotides, the chemicals that also form DNA.  (Interestingly, among the many natural foods AMP occurs in is breast milk–and scientists have long wondered why babies don’t seem to notice the bitter calcium compounds in breast milk.  It could be that AMP is blocking those bitter tastes.)

The researchers were able to discover AMP by first identifying gustducin, one of the receptors on taste cells that reacts to bitter molecules.  AMP binds with gustducin before bitter molecules can, and unlike the bitter molecules, AMP doesn’t trigger the process that would lead to the recognition of bitterness by the brain.

AMP is probably just the first bitter-blocker to be patented; Linguagen’s researchers and others around the world, many funded by giant food corporations like Kraft and Coca-Cola, are racing to discover more.  In addition to better-tasting medicine, all this research could also lead to better-tasting, healthier processed foods containing less sugar, salt and fat.

It’s estimated that we could have as many as 20 receptors for the bitter taste (again, probably because bitterness is a warning of poison in naturally occurring foods), and AMP doesn’t block them all, another reason the search for additional bitter-blockers continues.

Interestingly, there are apparently only two sweet receptors, which could mean that finding a substance that blocks the sweet taste would be relatively easy.

Except, of course–who would want to?

Permanent link to this article: https://edwardwillett.com/2003/02/bitterness-blocking/

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