Super tasters, genes and pepper in your pool

Since humans developed language tens of thousands of years ago, we’ve found expression for phenomena only now being explained on many levels, right down to the molecular, by scientists.

Almost instinctively, and certainly by experience, we understand that one man’s meat is another’s poison – an adage that applies in spades to the world of wine.

When scientists recently announced, for example, that cheese mutes the flavour of wine, wine trade veterans simply said, we told you so — and quoted the old wine merchant adage, “buy on apple; sell on cheese”. Those who trade in wine have known for centuries that apples sharpen the palate and cheese dulls it.

More pertinent to the meat/poison divide, though, is emerging evidence that our differences on what tastes good or bad isn’t just a matter of opinion. It seems to be in our genes. And it’s not just a matter of pleasant and unpleasant, but a whole range of individual experiences based on what we see, smell and taste.

The Aussie wine industry has long known, through observation and measurement, that we all have different thresholds for recognising certain aroma/taste elements in wine — especially for potential faults such as excess volatile acidity (vinegar) or trichloroanisole (TCA), the molecule behind cork taint.

Where palates can be sensitised to recognise the latter, there are other tastes and aromas that we either sense or don’t sense. Mousiness – a bacterial fault derived from the spoilage yeast brettanomyces – is a real life example.   It can make one taster gag while another smells nothing but wine. The ability to sense mousiness, I’m told, lies in the genes.

Yet long before scientists identified the blind spot as being in our genes, wine show judges had learned that the shortcomings of individuals needed to be addressed – just one of the reasons for using three-person judging panels.

And only last year, following five years of work, the Australian Research Institute revealed yet another example. They discovered the chemical behind the peppery aroma of shiraz, alpha-ylangene

But to the twenty per cent of people unable to sense the compound (another of the Institute’s findings) it’s of little comfort knowing that ‘a single drop is enough to make an entire Olympic-size swimming pool smell peppery’.

With taste at the centre of the wine industry’s existence, it’s not surprising that the venerable Institute of Masters of Wine amongst others, has become interested in the phenomenon of the super taster – a class of taster categorised by scientists researching genetically determined ability to taste.

Super tasters have an acute ability to taste the very bitter synthetic substance phenylthiocarbamide (PTC) in tiny concentrations – where others taste little or nothing.  Within the human population the concentration at which we sense PTC varies by a factor of one thousand.

In a Science a Go Go article in September 2005, Rusty Rockets, reported that, according to Professor Patrick MacLeod, president of the Institute of Taste, at least half of the 347 olfactory genes identified in humans are polymorphous, “meaning they have a great potential of variation amongst themselves” and giving “credence to the claim that no two people will ever taste or smell the same odor the same way”.
At about the same time, in, Richard Farmer reported that Professor MacLeod’s experiments have also revealed “the colour of a wine – which is visual information – can truly change the taste of the wine. This is not an illusion. A white wine that has been tinted red with an odourless dye will taste different and creates a different pattern of neural activity in the brain”.

According to Rockets, Professor MacLeod also points out that a “single molecule can provoke a response in a single cell that is then transmitted to the brain”—suggesting that “the human sensory system for odors has achieved maximum sensitivity”.

The combination of acute olfactory sensitivity, genetic variance and the diversity of sensory cues influencing what we smell and taste begins to explain why wine remains infinitely variable and fascinating, It also says that behind divergent opinions lie utterly different individual experiences.

Copyright © Chris Shanahan 2008