jamie goode's wine blog: Yeast rocks

Friday, December 22, 2006

Yeast rocks

Nice piece in New Scientist today about brewer's yeast:

Some time in the distant past Saccharomyces cerevisiae, to give it its full name, developed a chemical trick that would transform human societies. Some anthropologists have argued that the desire for alcohol was what persuaded our ancestors to become farmers and so led to the birth of civilisation. Whether that's true of not, alcohol has had a huge influence on our history and our
I'm not sure I agree with the last paragraph, where it implies that there's s selective advantage for Asian populations to carry mutant ALDH2, which reduces their ability to clear acetaldehyde, produced by the metabolism of alcohol. Acetaldehyde is a nasty molecule that acts as a carcinogen: there's a good incentive for clearing it as fast as possible. It's more likely that Asian populations, which have enjoyed teas as their traditional beverage rather than beer and wine, haven't had the same selective pressure on them to metabolize acetaldehyde as efficiently.

Labels: , , ,


At 8:57 PM, Anonymous Anonymous said...

Jamie, how much influence does yeast have on flavours and do wild yeasts really make more interesting wines?

At 12:32 AM, Blogger Richard & Catherine said...

Consider yourself festively "tagged" with the current blogisphere 'meme' doing the rounds...

You can see the explanation on Ruth Gledhill's blog:
...and my rather tame answers:

Looking forward to your five! :o)

**Merry Christmas Jamie**


P.S. Good question about the yeast - I'd always assumed one yeast was much like another in its effects?

At 6:10 PM, Blogger Jamie said...

Anon and Richard,
Yeasts make much more difference than we'd like to the flavour of the wine. It's kind of hard to do this topic justice in just a few sentences. Wild yeasts make a difference, too - in part because they contribute different characters, but also because a wild yeast ferment starts off much more slowly, which changes the whole maceration process. Simplistically, interventionist winemakers can use specific varieties of cultured yeast to alter wine style; traditionalists prefer to use either natural yeasts, or neutral cultured yeasts; and some winemakers even consider the native yeast present to be part of the terroir (local character) of the wine.

At 7:39 AM, Anonymous Stephen said...

Jamie, if acetaldehyde is such a bad carcinogen, have you come across any (epidemiological) studies that indicate Asian populations (ALDH2 mutant) are more at risk to liver cancers.

At 11:27 PM, Blogger Jamie said...

Stephen, good point. I need to double check this, but I think that those with ALDH2 mutations are at much higher risk of mouth and oesophageal cancer. Will get back to you on this one.

At 4:22 PM, Anonymous Doug said...

On the subject of wild yeast the answer is certainly "yes" - it does have an influence on flavour; secondly, wild yeasts are generally perceived as less predictable, therefore, if you want to make a stable, consistent wine you may, as a winemaker, prefer to inoculate with a particular cultured yeast. Considering how important lees-stirring is to the process of adding texture and flavour to wine then the quality and composition of the yeasts will be significant. Bergerac vigneron Luc de Conti has identified over three hundred indigeous strains in his vineyard and winery; he chooses to make a paste or mayonnaise of the lees and reintroduce it to the wine for added complexity.

The flavours of wines made with cultured yeasts are necessarily more obvious inasmuch as a single strain will have been identified and specifically selected for certain desirable characteristics. In one sense they are beneficial to the winemaker as they allow for more predictable fermentations and assist in creating stylistically-similar aromatic wines. Typically, for example, Chardonnay will ferment much more slowly with wild yeasts than with one strain of cultured yeast. With a slow, lengthy wild yeast fermentation, it is more difficult to predict the outcome, positive or negative, because the winemaker does not know which yeast strains are active in the fermentation process.

Nevertheless (and if you believe that it is a natural product rather than the result of flavour profiling) being predictable and consistent is not necessarily what wine is about. Since yeasts are wild, living organisms they will contribute to the flavour and character of the wine if allowed to do so.

Finally, a poem I found extolling the wonder of wild yeast. Admittedly, it's about making bread, but the principle's the same...


Rumbling a way up my dough's heavy throat to its head,
seeping the trailed, airborne daughters down into the core,
bubbles go rioting through my long-kneaded new bread;
softly, now, breath of the wildest yeast starts to roar.
My hands work the peaked foam, push insides out into the light,
edge shining new sinews back under the generous arch
that time's final sigh will conclude. (Dry time will stretch tight
whistling stops of quick heat through my long-darkened starch.)

How could I send quiet through this resonant, strange, vaulting roof
murmuring, sounding with spores and the long-simple air,
and the bright free road moving? I sing as I terrace a loaf
out of my hands it has filled like a long-answered prayer.
Now the worshipping savage cathedral our mouths make will lace
death and its food, in the moment that refracts this place.

Annie Finch


Post a Comment

Links to this post:

Create a Link

<< Home