"The grape press is where the wine is born, where it comes into the world.
The grape press is where the life of the wine begins ..."
Monique Charpentier Cellar Master
On arrival at the pressing centre, each batch of fruit is pressed separately according to grape variety and growth, never more than six to eight hours after picking, working day and night.
It is at this point that the major share of the harvest passes into the hands of the Champagne Houses. The buyer (or the buyer’s local representative) checks that, as the time-honoured phrase has it, the grapes are sain, loyal et marchand (sound, fair and marketable)
Appendice: Setting the sale price of the grapes
The setting of the actual sale price is based on a freely negotiated agreement between each Champagne House and its grape suppliers. It reflects the relationship that exists within the framework of the House’s long-term contracts with growers and is agreed privately between the two parties. The price varies according to the quality of the grapes in any given year, but also depends on the grape variety, the region and even the terroir and individual growth. L’echelle des crus (scale of growths) that was once the official quality scale is still often used as a reference document.
Champagne grapes are "the most expensive in the world" because each plot is tended as lovingly as a garden, with a minimum of 8,000 vines per hectare. One bottle of Champagne requires the equivalent of all the fruit from a single vine.
Stages in winemaking: Pressing
The pressing technique is strictly regulated and regularly updated to meet the uncompromising quality standards of Champagne Houses and Growers.
The grapes clusters must be placed whole and intact in the press — a condition that for the time being at least rules out mechanical harvesting.
Press yields are set at 102 litres of must per 160kg of pressed grapes.
The juice is "fractionated" as it leaves the press, separating the 20.5hl of clearer, purer juices drawn off at the beginning – the cuvée – from the 5hl of juice produced at the end – the taille.
All pressing equipment must comply with precise technical specifications (the cahier des charges).
The rules of pressing are designed to safeguard the quality of the grapes and prevent the pigments found in dark-skinned Pinot Noir and Meunier grapes from colouring the must. These rules also ensure that the process of juice extraction is not conducted at the expense of those analytical and organoleptic characteristics that play a defining role in the making of sparkling white wine.
The grape presses are also subject to strict rules. These are the key approval criteria:
The pressing centre plays a pivotal role in the Champagne Appellation approvals process. It must comply with very strict regulations drawn up by the industry and the Institut National des Appellations d’Origine (INAO). These cover every aspect of pressing, from the types of press used to the racking facilities and indeed the premises themselves. Everything that makes up a pressing centre must comply with approvals criteria as defined by Champagne’s cross-industry body (the interprofession) within the framework of a Quality Charter that was put in place in 1987.
Pressing equipment covers a broad spectrum of requirements and has developed continuously over time. Designed to keep pace with the Champagne quality improvement policy, the pressing technique meets strict requirements based on tried and tested experience. These include:
To these technical requirements are added those of a human order (to do with the workplace), looking to maximise the workflow by reducing downtime (particularly important to allow pressing immediately after picking) and implementing automation wherever possible (to relieve boredom at work).
Five types of press are used in Champagne, each one with a quite different operating mechanism.
These presses still account for nearly half of all plant and one third of all Champagne grapes pressed. The chief manufacturers are Coquard, Darc, Dol-lat and Marmonier.
A plate is lowered onto grapes contained in a circular or square-shaped basket. Since the basket is fixed, the juice percolates across the press cake (the gâteau de marc) and runs away down the sides and base of the press. The press cake is broken-up with pitch forks between each pressing to bring the more lightly-pressed edges of the cake back into the middle — a manual operation known as the retrousse. Vertical fixed basket presses have a capacity of 2,000kg or 4,000kg of whole grapes.
Juice is extracted by pressing the grapes between two vertical plates that are mounted on a central screw. Rotating the screw and the cage in opposite directions saves time and reduces the need for manual intervention. Slots in the cage (or cylinder) allow the juice to flow out. More recent, so-called "Champagne" models allow a stepped increase in pressure depending on the strength of flow.
Known as the Vaslin press, this was the first automated press and was introduced in Champagne in the mid 1950s. Capacity ranges from 2,000 to 4,000, 8,000 or 12,000kg of whole grapes depending on the size of machine. Vaslin presses account for one third of Champagne plant and one quarter of all grapes pressed.
Manufactured by Mabille, this type of press can handle 6,000kg of whole grapes. It was the first-ever press to function by means of compressed air: pressure is applied directly to the press cake by the inflation of an internal membrane (or bladder) that runs along the central axis of the press. Despite its highly innovative design, this system of pressing is rarely used in Champagne, partly because the bladder is prone to puncture and partly because it restricts the automatic filtration of the must.
This press comes in four models with respective capacities of 2,000, 4,000, 8,000 and 12 000kg of whole grapes. Manufacturers include Bücher, Diemme, Jouglet, Mazancourt, Péra, Siprem and Willmes.
Here the axial bladder is replaced by a synthetic membrane that is attached diametrically opposite the cage. The tank is closed but fitted with internal drains that connect with the juice collector. Pressure may be supplied by compressed air or water, with the whole pressing programme now largely computer controlled.
This is the latest innovation in pressing, introduced in 1985 and manufactured by Coquard. It comes in three sizes with respective capacities of 2,000kg, 4,000kg or 8,000kg of whole grapes.
How it works: a lateral pressing action is created by two tilted, hydraulic pressing plates. As the plates withdraw, the press cake breaks up spontaneously, crumbling under its own weight. The basket then tilts at 90 degrees, producing a flow of juice that runs away through the perforated sides of the basket and the slots in the cage. Unloading is automatic and the pressure is stepped up by degrees. These days, the rate of pressure increase is computer controlled.
Horizontal presses (pneumatic and hydraulic) account for one quarter of all plant and one third of all Champagne grapes pressed. Both types are increasingly popular with Champagne producers.
Champagne presses are designed for a slow, gentle, gradual increase in pressure, keeping the number of retrousses to a minimum. While manual pressing is best for such a delicate operation, it requires a level of supervision that is just not compatible with the rapid pace of work at harvest time.
Technicians from the AVC (Association Viticole Champenoise) joined forces with members of the industry and press manufacturers to resolve the issue without compromising Champagne’s standards of slow, gradual extraction. They drew up a set of specifications that limited the duration and degree of pressure to be used with Champagne grapes. This in turn led to the development of computerised consoles with multiple programs that allow the operator to vary the pressure depending on grape variety and degree of ripeness. There are currently three types of console that meet these specifications:
- First-generation consoles, with preset programs (manufactured by Bücher, Coquard, Diemme, Jouglet, Magnum, Mazancourt, Péra, Siprem, Willmes).
All operations are pre-programmed: staged increases in pressure, optional choice of stages, duration and intensity of retrousse. The program is selected at the outset depending on the grape variety, and can be modified manually at any moment in the course of pressing.
- Second-generation consoles, with computer-controlled flow rates and delay times (manufactured by Diemme, Jouglet, Péra, Siprem, Willmes).
The duration of each pressing automatically corresponds to the frequency of the pressure adjustments required at a given pressure level, with no manual intervention. Two pre-set times are already programmed: the adjustment time and the maximum time that a given pressure level may be maintained. The intensity of the retrousses is also pre-set.
- Third-generation consoles, with computer-controlled measurement of actual juice flow (manufactured by Bücher and Péra).
Tested in the 1994 harvests by the AVC, this type of console allows precise measurement of actual juice flow (thanks to a flow meter connected to the press) and from this can be deduced the volume flow rate. The amount of time that a pressure level should be maintained, the rate of incremental increases in pressure at the end of pressing and the intensity of retrousse are all software-controlled. This type of console provides a high level of security.
The purpose of pressing is to extract juice from grapes. The clusters are very fragile and must be handled with great care to keep them in perfect condition.
The basic principle is very simple. First, the press basket (maie or drum or cylinder) is filled with the marc (press cake consisting of some 4,000kg of whole grapes). The plates, held in place by stays or metal brackets, are then lowered over the grapes, using a ratchet to apply slow, discontinuous pressure. The pressed juice flows out between the staves of the press.
The quality of the wine depends on its sugar content, its tartaric and malic acid content and its potassium content. These elements are contained in the grape pulp. Working from the inside of the berry out towards the skin, juice is most easily released from the weakest pulp cells in the grape’s intermediate zone (1); then from the pulp cells in the central zone (2) and the peripheral zone (3).
The objective of fractionated pressing is to extract the constituents from these three zones, one by one. Since Zone 1 is the first to release its juice, the cuvee is richer in sugar and acid, better balanced and more fragrant than the taille. In short, it has a different chemical composition, untainted by pigments and not discoloured by oxidation. The taille is fruitier, less acid and slightly coloured due to the presence of mineral and albuminous substances, pigments and colloids in the must.
The cuvee and the taille are therefore fermented separately, emphasising quality over quantity in line with the time-honoured principle that applies at every level of effervescent Champagne-making — from tending the vine to the production of the finished wine.
After the cuvee and the taille have been extracted, there is a final pressing of the grapes known as the rebêche, which is by law sent directly to the distillery to make alcohol.
The residual skins, stalks and seeds left behind after pressing, aignes in French, are fermented then distilled to produce Marc de Champagne.
The cuvee and taille musts flow into separate tanks (the belons), with any solid substances (particles of skin, stalk or pips) filtered out through stainless steel mesh. A very small quantity of sulphites is meanwhile added to conserve the integrity of the musts.
Sulphuring also facilitates the decanting of the juice by promoting solubility and flocculation, which in turn improves the natural precipitation of the sediments (bourbes) in the musts. Natural pectinolytic enzymes catalyze much the same reaction.
From the belons, the musts are transferred to new tanks for clarification (débourbage) where they will remain for 12-24 hours. At the end of this time, any particles in suspension will have sunk to the bottom of the tank. Decanting is a two-stage process:
From the moment of arrival at the press house, every operation is recorded to guarantee the traceability of the musts.