Taste Test

I’ve been contributing a column about taste and flavour to an admirable new on-line magazine called Flavour First (see http://www.flavourfirst.org). I thought I would recycle them in this blog just in case some faithful followers might have missed them.

At the Fat Duck, they used to serve a little nibble to kick off any meal. It consisted of a rectangular tablet. One side was orange and the other deep purple. One side was orange jelly and the other beetroot jelly, the solicitous waiter would explain, adding ‘I suggest you start with the orange.’ This being the Fat Duck, the orange jelly turned out to be beetroot, being made with yellow beetroot, and the purple side taste of orange, being made with blood oranges.

It was a classic case of misdirection, and produced a palpable sense of shock, just as you experience when you pick up a glass of water swig it and discover it’s really vodka, or, even worse, the other way round. Our relationship with taste and flavour starts long before we actually do any eating. It begins when we smell food and/or see it. At that moment our brains whirr into gear, setting up a series of responses and expectations.

Only after that come the responses when we actually put the stuff into our mouths. We push it around with out tongues, assessing texture chew on it a few times, releasing its juices, and that’s when we ‘taste’ things.

In easier, simpler days there used to be just four tastes – sweet, sour, salty, bitter. Then they were joined by a fifth, umami, natural MSG, best described as a savory facilitator for other tastes. We had known about it since being identified by Kikunae Ikeda in 1908, but Western experts remain skeptical about its existence and importance until 2001 when Prof Charles Zuker proved that we had taste receptors specifically for umami.

Taste receptors – there’s another area of debate and changing knowledge. I can remember the days when it was thought we only had about 300 receptors, and it was generally accepted that these were located on the tongue, around the mouth, and in the throat. At the last count it turned out that there are over 2000 to 5000 taste receptors (scientists is always revising the number upwards) dotted all over the place, including in our tummies, gut and pancreas.

It was also once thought that each receptor has specific functions in relation to the five basic tastes, i.e. 1:1. Now It seems that taste receptors are rather more promiscuous than we previously thought, in that predominantly bitter receptors, let’s say, also register degrees of sweetness, and ditto salt receptors for bitterness and so on. And if that weren’t confusing enough, taste receptors vary from person to person, and aren’t all switched on all the time. There are specific taste hotspots in the brain, too, which respond to specific tastes.

Once upon time, everything was so clear. We tasted tastes in our mouths and while our olfactory bulbs sorted out the flavours. Now no one seems able to decide where taste ends and flavour starts. As far as I can make out, most authorities treat them as if they merge one into the other.

But, but, but, it seems to me that there’s still some kind of separation. If you don’t believe me, try the old squeeze-the-nose test. Eat a pear squeezing your nose, and you’ll be hard put to tell whether it’s an apple or a pear. Then unsqueeze your nose, and the pear flavour will fill your head. But if you chew a lemon squeezing your nose, you can tell it’s a lemon by its acidity, because acidity is a taste. All clear now? Mmmm.

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