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Monday 25 January 2021

The sweet taste of unknown

I eat my artichoke-aubergine breakfast dish (my vegetarian take on Antigua and Barbuda’s traditional aubergine saltfish breakfast), and take a swig of water. It tastes sweet. But then, I’m not surprised by that. Water always tastes sweet after eating artichoke.

Why is that?

It turns out scientists don’t actually know. The theory goes that cynarin, an acid found in artichoke, inhibits our sweetness receptors. When washed away (e.g. by a nice glass of water), the sweet receptors reactivate. Just as if you taste a really sugary drink and then slightly sugary one, the slightly sugary one won’t taste sweet at all by contrast (try it!), the same thing happens here: your brain goes crazy now the receptors is no longer inhibited, and interprets the water as sweet.

Great theory, but there remain a few unanswered questions. In the initial 1972 paper[1], two chemicals were implicated: cynarin and chlorogenic acid. This second chemical doesn’t get mentioned again, and it’s not clear what it’s effect is, only that it somehow contributes. What’s more, tests proved that actual artichoke had a bigger sweetening effect on water than either of the two chemicals tasted alone – we don’t know why.

Artichoke is known as a taste modifier, but it seems the effect doesn’t get everybody. For some supposedly genetic reason, only 60% of people get the sweetening effect from artichoke, making it a poor sweetener substitute.

A more common and effective taste modifier is miraculin (or miracle berries), which have the power to make citrus flavours sweet. I’ve used them myself. At one science event, excited customers keenly consumed lime after lime until we recommended they give it a rest to avoid indigestion later. Despite it’s popularity, scientists don’t know how miraculin works. One theory is that it temporarily alters the shapes of the receptors, so they pick up acids instead of sugars. Not long later, the miraculin customers sadly asked us how to get rid of the effect – so they could enjoy their now flavourless wine. Unfortunately, there was nothing we could do about that. Miraculin lasts for about an hour – it doesn’t wash away as easily as artichoke.

But would that block all taste perception?

Perhaps not.

Although scientists used to believe there was just one kind of sweet receptor on our tongue, new findings in sensory science are casting doubts on that. Scientists are now unsure how many sweet receptors we have – and we may have lots.

why don't all references have links?

[1] LM Bartoshuk, CH Lee, R. Scarpellino. Science, 178 (1972)

For more information, I recommend these books:
Why Does Asparagus Make Your Wee Smell?: And 57 other curious food and drink questions, Andy Brunning (2015)
On Food and Cooking, Harold McGee (2004)

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