The rules applying to the three AOC of Alsace, it is prescribed that vinification should be "traditional". But what is that? Fortunately, it is not the same thing as 30 years ago.In the following, vinification at a quality conscious producer is described.
Vinification of white Alsace wines begins the same moment as the picker stretches to reach the bunch of mature grapes. In order to retain the acidity and freshness of the grapes, the bunch must be handled with utmost care. Just as an apple, dropped to the floor, starts to oxidise within minutes, the qualities of grapes will deteriorate rapidly if treated without care.
The grapes are picked in the morning to facilitate cooling of the must after pressing. In the vineyard, the bunches are put into plastic containers holding 100−120 kg. The containers are transported to the winery and emptied straight into the press.
Nowadays, the grapes are not destemmed prior to pressing. Destemming was, in fact, a completely pointless practice that led to oxidation of the grapes before the must had even reached the fermentation vessel.
The modern, pneumatic wine press is basically a bag holding the grapes inside a pressure vessel. Pressing takes place as the pressure outside the membrane increases. The must is produced without any grinding at all. The pressing lasts for up to 4 hours according to an elaborate sequence of pressure increases, turning and draining.
Grapes that are not infected by botrytis undergo pressing that gives three fractions. The first fraction, a few % of the must, is called the "washing" fraction. It is dilute and contains a lot of the proteins released from the grapes. If not taken away, these proteins may cause problems at later stages of the vinification.
The second fraction is the main fraction of superior quality. The must from the second pressing should be quite clear, reducing the need for fining and filtering during later stages of the vinification. If the grapes are infected by rot, the pressing procedure is vital to ensure a fresh wine.
After a final pressure increase, the third fraction, used for Edelzwicker and other simplier wines is collected.
Normally, maceration is not practices for white wines. The sole exception is Muscat if absolutely free from rot. Pinot Noir undergoes maceration for up to 15 days before pressing.
After the pressing, the must is cooled to 4 C. AT this stage, a large part of the sediments is allowed to settle for some 48 hours. At this temperature, the fermentation will not start. The clarification of Gewurztraminer may often be a problem at this stage, leading to very rapid fermentation later on.
Chaptalization in the range of 1.5-2 % is allowed (each % corresponds to 16.83 g/liter of sugar). On some Grand Crus, Pfersigberg among others, the local growers association has decided to apply additional restrictions.
Even though each producer applies a unique pressing sequence, the secrecy starts at fermentation. While many producers will, if asked, simply state that they let nature do the job, the winemakers will apply a certain temperature sequence to create a certain character of the final wine. For example, some growers may stimulate formation of certain intermediate fermentation products by keeping a low temperature during the initial stages. Another strategy is to control the temperature to get equal rate of fermentation for a certain period of time.
In the New World, cold fermentation at 10-12 C is common. However, this may lead to "amylic", flavours of banana, melon, pears etc. These flavours are not typically associated for Alsace wines of high quality.
The house of Leon Beyer produces super-dry Riesling with levels of residual sugar as low as 2 gram/liter. At a dinner in November 2007, Yann-L&eact;on Beyer told me that they cultivate a "booster" from yeast of the fermenting wine. They use the booster to stimulate the fermentation at the final stage of fermentation.
Fermentation normally lasts for 4-6 weeks. Sweeter wines of VT and SGN quality may ferment for a year, only undergoing occational batonnage. The fermentation of these wine takes extra long time since the sugar itself, the alcohol produced and the botrytis fungi inhibit the yeast fermentation.
Fermentation is stopped by cooling the wine (not by sulphur addition). As the yeast is kept in suspension by small bubbles of carbon dioxide attached to the particles, the suspended solids will settle as fermentation is stopped. Some producers store the wine on the lees, others transfer the clarified wine to a storage vessel.
Some growers choose to carry out "cold stabilisation". That means that the wine is kept close to freezing for some time to allow the (anions of) tartric acid to precipitate as potassium tartrate. This process diminishes the taste of acidity. Since the anions of th acid are precipitated with potassium, more acid is protolysed , releasing more protons causing a drop in pH as the acidity is removed.
White wine contains three main acids:
Tartric acid is the strongest acid and gives the wine it backbone. Malic acid is sharp on the palate, and gives the wine a green character. Many growers allow the wine to undergo malo-lactic fermentation. In this process, 2/3 of the malic acid is turned into lactic acid, and the wine gets a softer character.
Some wines benefit from malo as they get a more complex character. However, they may also soften to much and get flavours of milk and yougurt. Some growers, such as Bruno Sorg, argues that if the grapes are mature at harvest there will hardly be any malic acid to transform anyway.
Malo only takes place spontaneously at relatively high pH-values. Hence, if the aim is to soften up a wine from a cold year, special starters may have to be used. If malo should be prevented in a high-pH wine, extra sulphur may be needed.
I have the impression that by principle advocates of natural wine making, such as Bruno Scheuller and Sylvie Spielmann are less bothered by malo than producers that have a specific style, such as Trimbach.
Prior to bottling, which takes place in August at latest to give room for the next harvest, the wine is stored in stainless steel tanks or big vats, foudres. The wood is said to allow the wine to lose some of the unwanted esters.
On the way from tank to bottle, the wine is filtered to remove remaining particles as well as most of the carbon dioxide. Some additional sulphur is added prior to bottling.
There are successful growers such as Pierre Frick, Bruno Schueller and Christian Binner who produce some wines without the use of sulphur. Instead they create reducing conditions at critical stages of the vinification. They all produce wines that mare far from main-stream, but are all very good and interesting.
If you ask a producer details about his/her vinification, do not expect to get complete answers. Although Alsace growers are very generous there is no point to tell a visitor all their secrets. There are many tricks of the trade involving special yeast cultures, deacidification, reacidification etc.
However, as a customer, you can always be convinced that Alsace wines are marginally "styled". The basis for the impressive standard of Alsace wines is the skill of the grower and winemaker combined with sound use of technology, not artificial and unnatural methods at a large scale.