New World Winemaker Blog

There’s little need for me to rehash the back-and-forth in the wine media regarding alcohol levels: in short, the wheel has turned and we are back in the 1980s when it was fashionable to criticize California wine for having high alcohol.

Here we are again. The difference this time around is that there is a hard number on the lips of the critical: 14%. The narrative being pedaled suggests that wines over this level generally are problematic, inferior, out-of-balance, not true-to-type, lacking: terroir, focus, complexity precision, nuance, etc.

I disagree.

And I’ve commented here and elsewhere that I have noted zero interest in the topic among the visitors to our Tasting Salon. But the “over 14% sucks” meme has a life of its own, it’s out there, it won’t die; sort of like “the President is a foreign-born Muslim.”

Because of this persistent media attention, I figured that it was bound to happen—sooner or later—that one of my guests was going to comment on the “high” alcohol levels on the labels of my wines.

It happened like this. Three nice people came in and tasted through the five wines I had on offer: three Pinots, a Châteauneuf-du-Pape-style blend and last, a varietal Syrah. They seemed to be enjoying them. After the Syrah one of the guests asked “What’s the alcohol on these wines?” I answered “between 14.5% and 14.9%” and a couple of them started muttering “oh, that’s high—so-and-so won’t drink it.”

I politely asked them if they could have guessed that the wines had alcohols approaching 15% without being told, and each of them admitted “no” they couldn’t have. One commented that “…these wines don’t taste hot.” I explained that ethanol doesn’t really taste hot, but that other alcohols do—propanols, butanols, pentanols, etc. and their esters and oxidation products, collectively called congeners in the distillation biz.

These fermentation products are more likely to be produced by yeast under stress, and high initial sugar as well as high final ethanol concentrations are potent stressors, as are nutrient and co-factor deficiencies. In my winemaking I go out of my way to minimize the stresses on yeast (though not so far as to throw diammonium phosphate—DAP, a source of ammonia—at every ferment) and so the levels of these congeners are low in my finished wines. No “heat” on the palate.

I further explained that in fact few of my wines finish fermentation much over 13.5%-14% but they pick up as much as 1%-1.5% during barrel aging. This is because we have a dry barrel cellar. Inside the barrel there is 86% water and 14% alcohol, while outside there is an average of 30% water and 0% alcohol. To a first approximation, the thermodynamic drive for water to leave the barrel is over 3x what it is for alcohol, and so over the course of 2+ years aging in barrel the alcohol level of the wine inside actually goes up.

A wine made from grapes harvested at “optimal” ripeness and put to barrel at 13.5%, in our cellar may well end up near 15% when it is ready to go to bottle. This is not the same as harvesting the grapes over-ripe. Not only do these wines not taste hot, they don’t taste raisined.

Anyway, the offshoot was that these folks bought a case of wine, and intended to put some of in front of their “I won’t drink any wine over 14% because wine over 14% all tastes the same” friends and see what they think. Awesome.

John Kelly is the owner and winemaker of Westwood Wines, Sonoma California. This blog was originally published on his blog: “notes from the winemaker” on the 3rd of January 2012 at 14h52 to be precise.

Recent crackdowns on doping in sport have made all of us more aware of the effects of performance enhancing supplements. This got me thinking. What if winemakers could come up with a legal magic potion for yeast? Like the magic potion that enabled Asterix and Obelix to defeat the Romans time after time. Something that would give mere mortal yeasts super human (rather super yeast) qualities?

An increasing worldwide trend is longer “hang-time”. Delaying harvest might increase berry aroma and decrease acidity, but it creates a unique problem for our little athletes. Increased sugar leads to increased alcohol levels in wine made with these grapes. Fermenting yeast thus run the risk of being smothered in the alcohol they produce as a result of them snacking on sugar. Fortuitously, there is a magic potion that you can give your yeast to boost their viability during fermentation.

First, let’s look at the definition of sterols: “Any of various alcohols having the structure of a steroid, usually with a hydroxyl group (OH) attached to the third carbon atom. Sterols are found in the tissues of animals, plants, fungi, and yeasts and include cholesterol and ergosterol.” Here comes the interesting part. Sterols and unsaturated fatty acids (UFA’s) are survival factors during fermentation, but oxygen is needed for the synthesis of said survival factors. With insufficient amounts, the yeast cell membrane functions poorly, especially during highly anaerobic conditions and especially with increasing ethanol levels. Inadequate sterol concentrations around flux controlling proteins in the yeast cell membrane cause damage to the cell membrane and ultimately results in cell death (read: stuck or sluggish ferment!). The key role between oxygen and sterols now becomes evident. Simply put, controlled and timely oxygen addition = more sterol synthesis = better ethanol resistance = happy yeast = happy winemaker.

In my previous life, I’ve found it useful to add oxygen to red ferments anytime from a third of the way through alcoholic fermentation, up to halfway. This roughly corresponds with the end of the cell growth phase and research has shown that an oxygen addition of five to ten mg/L has a very positive effect on cell viability. Another trick is to combine oxygenation and nutrient addition with a pump-over or punchdown. Complex yeast nutrients contain inactivated yeast, which is a good source of sterols. The abovementioned trick also counteracts reductivity, which every winemaker deals with at some stage.

Research is ongoing to gain more insights into how yeast sterol uptake and synthesis affects cell viability. Ergosterol is one of the main compounds being studied, but I’ve also read a paper which outlines the addition of cholesterol to a fermentation! Fermenting yeast are just as happy with cholesterol as they are with ergosterol, but I seriously doubt if winemakers will be chucking cholesterol by the bucketful into their wholesome red wines!

Bernard Mocke is a technical consultant for Oenobrands.

Part one of this blog gave us some background on high Brix grapes, musts and the resulting high alcohol wine. The easiest (but not always legal) way to counter the effects of a potential high alcohol ferment is to add water to the must. This is usually done prior to fermentation. In warmer viticultural countries, winemakers often employ this technique to dilute musts from grape varieties that are harvested at 27 to 30ºB or higher! The arguments against this moist method are quite watered down by now, but the critics have a valid point. For instance, when you add sugar to wine (chaptalization, as it is called in France), you mainly alter the production of alcohol in the finished wine. However, the addition of water dilutes and impacts an innumerable amount of aroma, tannic and other chemical constituents. So there are obviously two sides to this rather soggy debate.

In California, the addition of water may only be done to prevent a stuck fermentation. Section 17010(a) of the California Administrative Code states: “…and no water in excess of the minimum amount necessary to facilitate normal fermentation may be used in the production or cellar treatment of any grape wine…”. In the less liberal South Africa, the addition of water to must is still in breach of EU wine law and in all probability will still be illegal for quite some time. Some producers (notably in California) take watering back a further step. After bleeding off some of the juice (saignée), water is added to the tank. The initial step drastically alters the juice to skin ratio and decreases the amount of sugar in the must. The watering back further dilutes the sugar concentration. I have heard (and don’t have the hard facts) that another method to eventually reduce alcohol is applied in Australia. It is legal to add water that has been removed from juice via reverse osmosis to other juice or wine seeing that it originates from grapes and not the “black snake.”

Winemakers all over the world are probably most comfortable with reverse osmosis to remove access alcohol in finished wine.  Portable units are available that can be used to treat your high alcohol wine and thus effect a significant decrease in alcohol concentration. Another technique is the spinning cone technique, which fractionates wine. After alcohol is removed, the desired volatile components are simply added back to the wine. The downside to these techniques is that important aroma compounds and mouthfeel can be lost. As a winemaker once elegantly put it after treating a high alcohol wine with reverse osmosis: “The alcohol level is acceptable, but now we’re stuck with a bland, soulless wine.”

The winemaker will ultimately decide how the alcohol issue should be remedied. To those that believe that no superior winemaker has ever added water to wine, I guess the American Army policy of “Don’t ask, don’t tell” (Google it if you don’t know what I’m talking about) will be interesting and enlightening reading.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.

One of my favourite stories from the Bible is the one where Jesus turned water into wine during the marriage at Cana. Despite this incredible event, asking most winemakers today whether they dose their ferments with water is like asking somebody about his brother in jail… you just don’t talk about it.

The International Organisation of Vine and Wine (OIV, if you parlez français) prohibits the addition of water in all of its 44 member states, which includes countries such as South Africa, Australia, Chile, Brazil, Uruguay, New Zealand, Austria, Croatia, Czech Republic, France, Germany, Hungary, Italy, Israel, Slovenia, Spain and Turkey. But why is the addition of water such a touchy topic? To answer this, we’ll have to hop into the vineyards and consider the interaction between the sun and the water content of ripening grapes.

Research done in Australia on Shiraz (Australia’s most planted grape variety) showed that ripening grape bunches can lose up to 20% of their weight (all of it water) at the end stage of ripening. The effect of the sun is obvious. This exodus of water basically concentrates sugar, which is further increased by the ripening effect of the sun. Wine producers in the southern hemisphere (i.e. Australia and South Africa) and even northern hemisphere (California) are often faced with the imbalance between grape sugars and tannins (and all the other critical flavour compounds). The problem is thus: sugars develop and build up during the harvest. Often, the heady tannins and usual aroma suspects arrive when the party is almost over, or in other words, when the grapes are already overripe. French winemakers critical of watering back wine (this should more or less include all of them) often state that sugars in their grapes develop more slowly and is thus in concert with phenolic ripeness. For an interesting debate, just mention the word ‘chaptalization’ the next time you encounter one of these winemakers.

Winemakers fiddling with overripe grapes can encounter various problems. Simply put, high sugar musts can lead to stuck ferments, even when inoculated with commercial yeasts. If the commercial yeast does however have a sweet tooth and is impervious to high alcohol levels, a high alcohol wine can result, where an alcohol level of 15% or higher is common. The Lower Alcohol Lobby frowns upon high alcohol wines (for various health, safety and other socio-political reasons) and is a powerful driving force behind many health initiatives and various research projects at leading universities. Another factor is tax that is levied on alcohol in some countries.

What is a winemaker to do, apart from having grapes picked earlier and fermenting with yeasts that have a lower alcohol conversion factor? (The latter doesn’t really exist.) There are a few techniques available, of which adding water to wine is paramount in this blog. But you will have to wait for part two of this blog to read all about these controversial techniques.

Bernard Mocke is a technical consultant for Anchor Wine Yeast.