It was discovered by Mr Pierre SUDRAUD, Director of the Central Laboratory of Bordeaux at the General Directorate of Consumption, Control and Repression of Fraud, and Mr Serge CHAUVET, engineer at the same Station, who were also familiar with the Sauternes region. Then called Selective Cryoextraction, it was announced at the 26th National Oenology Congress in June 1986 in Saumur-Fontevraud.
Selective cryoextraction, 'cryoselection
was made official in 1987 by Professor Pascal RIBEREAU-GAYON, an eminent professor of oenology at the Bordeaux Faculty of Science. He called it " cold pressing ". Based on sound scientific foundations, which have never been questioned since their publication. Cold pressing has been legally accepted by the European Community.
It is not an additive operation. There is no addition of bodies exogenous to the grape, nor of compounds from grapes alien to the terroir, such as sugars, concentrated musts or sweeteners.
It is not a subtractive operation, as in other systems (reverse osmosis) where a fraction of the water is extracted from the overall juice obtained from all the grapes picked, including the less good ones.
It is an operation where no chemical phenomenon or product is involved.
It is a separative operation. One might be too quick to believe that the operation, by involving a change of physical phase, destroys the balance of the juice obtained. This is not the case, as the cold only separates the grains which, due to their deficient constitution, have been solidified from the other grains which are deemed suitable for the desired production and which have not been modified.
From the press, only the juice of the grapes that have remained in their natural state flows out.
The berries solidified by the frost, being incompressible, are found when the press is emptied.
It is only a division of the grapes: some eliminated, others selected.
For a D.O.C. WINE WHAT ARE THE CONSEQUENCES?
Respect for the land.
The integrity and identity of the terroir are respected as the juice flowing from the press is free of any foreign addition.
Respect for the vintage.
A tasting of more than twenty vintages from 1989 to the present day, organised anonymously and independently, could prove this today.
Sceptics might argue that cold pressing is a way of levelling out the vintage effect. For example, by standardising an identical saccharimetric degree each year such as 20° alcohol in strength. In small years, the price of such a requirement would be too high to justify its use because of the high proportion of unpressed grapes.
Cold pressing confirms the overall silhouette of the vintage because there is no single component, as in chaptalization, which can cause imbalance. The pressed grapes return a juice that is as completely attached to the vintage as if there had not been this additional method of selection. If there is a difference, it is the absence of unpleasant aromatic elements.
Cold pressing allows us to produce a wine that is true to its vintage.
Self-limitation of the increase in the saccharimetric degree.
The practitioner must determine the degree of cold necessary to preserve only the grapes with a saccharimetric degree corresponding to the desired wine. He needs to be methodical and observant (the know-how of the AOC producer) in order to assess the desired stage according to the state of the harvest.
A risk similar to that of over-chaptalisation (an increase of 3 to 6 degrees or more) is impossible because the low yield immediately punishes the error financially.
It is neither an extraction, nor an enrichment, nor a concentration. It is only a separation of the grapes chosen to obtain the desired wine: a selection, an additional sorting of only those grapes that meet the requirements of the AOC specifications.
Finally, cold pressing does not increase the volume of the wine from the harvested grapes as part of the harvest is eliminated, unlike chaptalisation which produces about 0.63 litres of extra liquid per kilo of sugar used. This is currently a windfall for the winegrower when the price of wine is high.
This self-limitation of cold pressing is an asset for the morality of the process and justifies a favourable reception of the public authorities towards it.
For sweet wines
Cold pressing leads to a more regular yield.
In a wet year, waiting for over-ripening often leads to a reduction in yield because the presence of grey or black rot "spoils", one could literally say "rots", the good juice of normally botrytised grapes.
At each sorting stage during the season, cold pressing not only increases quality but also saves losses by better and more selectively excluding grey or black rot.
Cold pressing does not replace manual selection.
On the contrary, they justify cryoselection more because the better the selection is carried out, well staggered and not postponed to the end of the season, the better the quality.
There are other factors which are important for quality.
- A reduction in off-flavours or deviant aromas: Grapes with advanced grey or black rot, because they are frozen, are excluded from pressing.
- Lower volatile acidity as the juice from berries with grey or black rot is eliminated.
A major asset.
Cold pressing removes any suspicion of the raw material since the fraction retained from the harvest is the only one to ensure future quality, without any doubt of an exogenous contribution or unorthodox handling.
It therefore ipso facto eliminates the establishment of approximate controls which become obsolete or are still insufficiently applied.
Only the juice that flows out of the press can be trusted.
It is sufficient to make the control compulsory at that moment.
At this stage, cold pressing safely restores the responsibility of the winemaker.
It can be said that cold pressing is a good moral operation for better quality.
The principle of cold pressing.
Given the heterogeneity of the berries in a bunch of grapes and the inadequacy of manual sorting to make the right choice, only a specific detector of the sugar content of the grape berry can select the berries suitable for quality.
It is known that pure water becomes ice at 0°. If an aqueous solution contains salty elements, such as sea water, the transition to a solid state requires a slightly negative temperature. The same applies to a juice that is more or less sweet, such as that of a grape.
It is enough to know how to press only the selected grapes, which have remained intact and unchanged by the lowering of the temperature.
The application of this principle.
The application of this principle is now made possible by the technical progress of modern mechanical engineering and its proper use. This is one of the facets of contemporary know-how that can legitimately be expected from the producer of AOC wines.
The required installation does have a cost, but it is proportional to the volume harvested. It is not an exaggerated handicap. It does not penalise small farms.
It is not an industrial process, as people would have you believe. Its application is based on modern cold production technology, but its application requires the know-how of a craftsman.
In 1989, we were the 11th French winegrower to turn to cold pressing and the first in the Loire Valley.
This has enabled us, as we have learned to do so alone, to gradually free ourselves from chaptalisation, whatever the vintage. We will not go back to the hypocrisy or concealment of old practices.
Our wines produced over more than twenty years have proven to be not only worthy of the AOC, but often leaders in their category. Most of them are kept in our private collection and can be used as evidence by any official body to demonstrate the validity of cold pressing.
Because we believe it is essential and useful for our northern region, this personal testimony, which is a practitioner's testimony based on a long-term, full-scale application, aims to tell the truth about a little-known or even obscured winemaking process and to encourage the profession to choose progress.
Jean & Florent Baumard, La Giraudière, February 2013