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Glutamate news
FIFTH TASTE IDENTIFIED
By Jamie Goode
20 March, 2002 - Scientists have identified
a new taste receptor that could change our understanding of wine tasting. The
results, published in leading scientific journal Nature, pinpoint for the
first time a receptor enabling humans to taste amino acids such as monosodium
glutamate, the widely used flavour enhancer. The existence of a fifth taste,
known by the Japanese term 'umami', had been suspected for a while. However,
in the absence of a receptor for amino acids on the tongue, there was some
debate about whether it might simply be a combination of the other tastes. This
new research by US scientists Charles Zuker and Charles Ryber shows conclusively that
umami is one of the basic tastes, along with sweet, salty, bitter and sour.
Zuker and Ryber studied a group of receptors
in taste cells known as ‘T1R’. They showed that when different T1R genes are
expressed in combination in taste cells, they enable the detection of specific
tastes: whereas T1R3 and T1R2 together produce a receptor for sweet tastes, T1R1
and T1R3 in tandem produce a receptor that recognises amino acids.
Wine contains some 1–4 grams per litre of amino
acids, which according to Zuker (who is a wine lover) would 'robustly activate
the amino acid receptor'. However, he told Harpers: 'Because the perception of
wine reflects the interaction of so many players in such a complex mixture, we
cannot assign a value to the contribution of the umami receptor versus the sweet,
sour, bitter and salty receptors.'
In theory, it should be possible to test the
impact of amino acids on the taste of wine simply by changing their levels. But,
Zuker added: 'I do not believe that this is a good experiment, since it is the
interplay of the various taste modalities that produces the final taste.' An
increased understanding of the way that human taste works raises the possibility
that winemakers could use manipulations that would help them design wines to
taste 'better'.
Reproduced with permission by
Jamie Goode, www.wineanorak.com.
Originally published in Harpers Wine and Spirit Weekly
Copyright ©2000-2001 Harpers. All rights
reserved.
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