jamie goode's wine blog: Tasting grapes - a remarkable aftertaste

Tuesday, September 23, 2008

Tasting grapes - a remarkable aftertaste

Time for some wine science. There was an interesting aside in Denis Dubourdieu's paper at the recent Austria conference. Denis is the man responsible for identifying a group of sulfur-containing compounds called thiols as being important in the aroma of Sauvignon Blanc.

Now thiols are made by yeasts from precursors present in the grapes. In the must, these precursors are odourless. The late Emile Peynaud, another famous wine scientist, remarked that 'it is winemaking that reveals the aroma hidden in the fruit'. Denis recalled how Peynaud talked about the aftertaste of Sauvignon grapes: 30 seconds after swallowing, you suddenly get all these lovely aromatics which weren't there earlier.

This reflects the transformation of precursors to aromas by the enzymes in the mouth. I was reminded of this comment when I tasted some almost ripe Phoenix grapes in my back garden today. They didn't taste of all that much, but after a minute or so I was getting these remarkable passion fruit/gooseberry aromas in the back of my nose.

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At 10:29 PM, Blogger Chief of Lab Research said...

Interesting at many levels. Like, how big is your backyard vineyard? But mostly this leaves me wondering about thiols and wine finishes. Given that thiols bind easily to skin proteins (quick check of wikipedia tells us thiols are what make it tough to wash off the smell of a skunk) is it thiols, this protein "stickiness" and their oral enzymatic interactions (try to say that three times fast!) that are responsible for the character and persistence of a wine's finish?

By the way, have been reading your Science of Wine. Terrific stuff.

J David

At 11:23 PM, Blogger Jamie said...

Backyard vineyard is small - just 20 vines - it's for fun rather than for making wine. Rubbish fruit set this year caused by hard pruning and bad weather at flowering.

Good question you raise.

thanks for the nice comments on science of wine.


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