'Natural' alcohol levels

[Comte Flaneur]

In the context of other threads recently, why are so called 'natural' alcohol levels so high these days? Surely it is not just down to global warming?

I was reading a review of LMHB 09, a wine which RMP rated 100, and said it could be drunk in six years but will last for 75. It achieved 15.1% natural alcohol IIRC. I gasped at that figure. Why are they so high and rising in Bordeaux and the rest of the world? I read elsewhere that high natural alcohol levels in the merlot grape are being identified as increasingly problematic in Bordeaux because it robs the wine of its traditional Bordeaux character.

What happened to the good old days of 12.5% ABV in our claret?

[JimHow]

Interesting question, Comte, but why do you think global warming can't be a significant factor?

[Comte Flaneur]

I should imgaine it may be a contributory factor Jim, but I find it hard to believe it is the only reason, because alcohol levels have gone up proportionately much more than temperatures.

[JimHow]

There are lots of articles/studies in Google on the impacts of global warming on winemaking, like this one:

http://www.wineanorak.com/global%20warming.htm

I wonder What Al Gore would say?

We're all doomed, and, cruelly, fine wine alcohol levels are just one of many canaries in the coal mine.

[Houndsong]

You'd have to call in a winemaker/grapegrower/consultant to explain it. It's possible the relationship of temperature and sugar production is non-linear. I would take a completely uninformed shot at it though and say "hang time" is behind it. It could be a matter of just a few days extra ripening might really accelerate sugar production. Plus if "lower yields" is not a myth - i.e. that they cause increased production/concentration of certain tannins, polyphenols, and other dowitchies in the grapes - you'd think it possible that the grapes have a higher sugar content too relative to water. In any case it doesn't seem accidental. The 2008 Fonroque clocked in at 14% in what has not been described as a remarkable vintage.

It might be instructive to look at the average harvest dates historically and see if picking is getting later. Obviously that could be a function too of the weather and not just a conscious choice to pick say a few days to a couple of weeks later. But without the data this is all just chat room speculation.

Also too in just the past week I have been struck by the use of the adjective "natural." I guess this means non-chaptilised?

[salilb]

As the Hound says, the lower yields and the viticultural practices in 'modern' winemaking have had an influence - most estates these days are slashing yields for fewer but riper grapes with higher potential alcohol, and on top of that you have aggressive pruning in a lot of vineyards that are meant to boost ripening.

Funny how estates that Arpy trashed at various points in the past for producing thin, dilute and weedy wines - e.g. Fourrier in Gevrey - seem to produce more delicate and finessed wines with a sense of lightness and balance, while having yields that RP and modern consultants have criticized for being too high.

[RDD]

Aside from sugar levels , the biggest factor controlling alchohol level is the yeast attentenuation.
So it would be interesting to talk to the wine maker and see what has changed in production.

[Houndsong]

That's an interesting point about yeasts, and it's not one I've seen talked about too much, at least not in the context of winemakers changing their yeast selections to crank up the volume. I was under the impression a lot of wines are produced with naturally occurring yeasts and while adding commercial or cultured yeasts is common and perhaps even the norm I'd be surprised that winemakers mess with yeasts as much as say brewers do when making different beer styles, for which you would want more or less attenuative yeasts to make drier/sweeter, or more/less alcoholic, or beers with different mouthfeel. I've got a Belgian triple sitting in a carboy right now that I know is about 9.5% and when it's done we'll see if it really came out as dry as it should for the style.

[Tom In DC]

When we first got into wine, yeasts seemed to be able to make around or barely above 1% alcohol for every 2 degrees Brix, at a conversion rate of just over 0.5. I seem to recall that typical conversion rates are around 0.6 now, or 20% higher alcohol for the same amount of sugar in the grapes. So, 15% is the new 12.5%.

[Houndsong]

So, what's behind it? Yeasts been hitting the weight room? BALCO?

[salilb]

How many (or do any) producers in Bordeaux use indigenous/native yeasts?

[Mike Christensen]

Yeast strains able to more efficiently convert sugar to alcohol (as Tom mentioned) and also able to withstand higher levels of alcohol. Back in the 70's, most yeast strains couldn't survive above about 15% alcohol. IIRC, the 1968 Mayacamas Late Harvest Zin shocked the winemaker by fermenting dry to about 16.1% (unheard of at that time). Most new-world winemakers use cultured yeasts and many of those have been cultured to allow higher alcohol conversion and higher tolerance for alcohol levels. You now see Zins regularly approaching 17%, not to mention Chardonnays (e.g. Brewer-Clifton) approaching that level...

The other thing was pushing Brix (which also went hand-in-glove with uber-yeasts). It used to be most winemakers would use Brix as the primary indicator of ripeness, typically deciding to harvest somewhere around 22-24 Brix (otherwise the yeast would die and leave considerable RS, which was a threat to go through secondary fermentation). Now, there are other methods used to indicate ripeness, and those tend to push Brix higher.

I wouldn't be surprised if most of the "modern" Bordeaux producers used cultured yeast. I can't imagine someone like Rolland allowing something as random as wild yeast to interfere with his formula.

[Houndsong]

I may have had it backwards, or perhaps I do now. I was laboring under the impression that grapes were getting ripe (i.e. tannin-wise) and then were being left on the vine to fatten up so to speak. I see now though that it's probably the opposite: The sugars are being produced and then the winemakers are delaying picking for the tannins to catch up? Which situation is exacerbated in really hot years, for example in 03, leading to situations where sugars and thus alcohols can be high but the wines can still taste green because the tannins didn't fully ripen before the grapes came in. Is that what's happening as the growing season becomes hotter on average?

[Mike Christensen]

The term is "phenolic ripeness" (tannins are phenols, but there are others, not just tannins). Phenolic ripeness and sugar ripeness do not always happen at the same time. In warmer climates, phenolic ripeness happens later than sugar ripeness.

[RDD]

That's an interesting point about yeasts, and it's not one I've seen talked about too much, at least not in the context of winemakers changing their yeast selections to crank up the volume. I was under the impression a lot of wines are produced with naturally occurring yeasts and while adding commercial or cultured yeasts is common and perhaps even the norm I'd be surprised that winemakers mess with yeasts as much as say brewers do when making different beer styles, for which you would want more or less attenuative yeasts to make drier/sweeter, or more/less alcoholic, or beers with different mouthfeel. I've got a Belgian triple sitting in a carboy right now that I know is about 9.5% and when it's done we'll see if it really came out as dry as it should for the style.

Now we're talking. I specifically mentioned yeast as it is so important in beer making. I've been specializing on ESB now. 10 Gallon batches.
But you have to consider winemaking in the same context. Beer has pretty uniform base ingredients. Marris Otter barley from same producer is pretty close to last bag.

Now wine is wonderful. Each property actualy grows their own raw materials. And as anyone who has grown a graden knows, certain terrior works better for certain crops. And the French have had this down tin their roots for many generations. But then the USA added analytical science (mostly Mondavi with temp control and barrel material/aging). More science with selection and propagation of yeast and super yeasts. Then throw in climate change and yeast that can best match a "riper" fruit and some hommage to Parker points and we live in a brave new world.
But then some properties stick to tradition .
We live in exciting times.
'Let's drink them in.

[Claudius2]

Guys
Don't assume that cultured yeasts lead to higher alcohol than natural yeasts.
From personal experience, this is a misnomer.
I did some work some years ago for a co-operative wine centre in Australia and the experiments with various strains of cultured yeasts compared to naturtally occurring yeasts were that the natural yeasts more often gave higher alcohol levels and sometime much higher, when used with the exact same grape juice.
The natural yeasts led to greater variation as well.
A lot of research has gone into yests over the years, and the main advantage of cultured yeasts is more predictability and less unexpected fermentation problems (stuck ferments, temp irregularities, etc).

Climate change is clearly a factor and the relationship between temps and sugar levels is not linear.
Also note that viticultural practices have changed, so have other aspects of winemaking and also market tastes.

Climate change is not the only factor by a long way and the alc levels in hot Australian areas like the Barossa have surged over the last 20 years but some makers make wine with say 13.5% for shiraz from the same sub-region, and others (eg, Greenock Creek) will make wine from literally the adjoining vineyards at alc levels that are 15% to 18.5% in the same vintage.

It is surprising to open an older Bordeaux (eg right bank Merlot based) and see 12% on the label and see the same property with 14.5-15% 20 years later.