The Verdú-Escuder method for making wines with no additives

Origin and beginning

In 2003, we set ourselves a goal: making wines which express the place of origin of the grapes from which they have been made. For this reason, we thought that we did not have to interfere nor provide any product, in any winemaking phase: fermentation, stabilisation and ageing. Therefore, we would not modify what nature provides to grapes through their genetic code and the environmental factors.

The idea, which started in 2003, was materialised with the bottling of the first wine from the 2012 harvest. Since then, the wine produced has been under observation until now.

In the winery:

• we do not use freeze‐dried yeast,
• we do not add sulphur dioxide,
• we do not clarify,
• we do not use cooling or any other products to detartrate,
• we do not make corrections to neither the grape juice nor the wine
• and we do not filter.

But, on the other hand, we have developed a protocol based on the implementation of different physical processes. The three winemaking phases in which we have changed the methodology are::

• Fermentation using infusion
• Stabilisation using intermittent mixing
• Ageing in barrels always full

Principle:

• Everything is covered, without any possibility of oxygen coming in.
• Fermentation is carried out in a strictly anaerobic way.
• The skins are always wet, first for the juice, and then for the wine.
• The CO2 is released freely through the valve.
• This way, the cap is never created.

Fermentation

In conventional fermentation of red wines, grape bunches are destemmed, and the grapes are crushed. The juice is mixed with the skins, the pulps, the seeds, and also with the yeasts, the lactic acid bacteria, and a huge number of exogenous microorganisms. All these things combined are carried, with a pump, to the fermentation tank. This tank receives all these products. Therefore, the destemmed and crushed grapes are together with the juice.

With the fermentation, the sugar is consumed, and CO2 is produced. The carbon dioxide tends to go up, towards the tank surface. During this vertical movement, the CO2 reaches the skins, and it pushes them up, accumulating them in a mass and creating what is called, the “cap” (“barret”). The pressure of the carbon dioxide pushes this cap above the juice surface. This movement causes part of the cap to go out of the liquid. It dries and, in contact with air, there are many possibilities that the volatile acidity increases, and besides, the quality factors provided by the skins cannot dissolve in the juice. Therefore, it is obvious that this cap must be manually immersed if the tank is small, and if we talk about a big one, a pump must be used to rise the juice up and put it above the cap so that the skins get wet. This work is usually done twice or more times a day while the wine is fermenting.

Description of the Verdú-Escuder method

The fermentation tank has two sections separated by a membrane filter. In this case, it is a cylinder with a stainless-steel mesh whose diameter is smaller than that of the tank, completely covered. The destemmed and crushed grapes get to the first section, and through the filter, which separates the two sections, the liquid grape juice is filtered without the skins to the second section until the two volumes are in balance. The tank is completely closed, without any possibility of oxygen coming in. There is only CO2 coming out through the upper valve in the cover. When fermentation begins, the CO2 produced tends to move towards the tank surface, and in this case, as it needs to make a lot of pressure inside the cylinder, it goes out through the side which has space. This way, the skins stay immersed in the grape juice, the cap is not created, and there is no need to do the work of immersing it every day. As the tank is completely closed, the whole fermentation is carried out in a completely anaerobic way. It is an infusion fermentation.

Advantages of the new method

The skins, as they do not create the cap, are wetted all the time by the grape juice, and all the particles dissolve easily in the liquid. There is no need to rise the juice with the pump to wet the cap. Therefore, this way of working allows us to save the energy for the pump and save the time of the winemaker too.

Materials

• A 500-litres (other volumes are possible) stainless steel tank, which is always full, and modified with a hole halfway up and another hole at the bottom for a flexible tube to connect it to a recirculation pump. In the hole of the bottom there must be an 8-cm tube welded, and with the end flattened, so that the wine comes out with more pressure.
• A built-in valve in the tank cover for the release of CO2.
• The tank should have a tap to take samples.
• A stainless-steel mesh cylinder with a smaller diameter than that of the tank, and its base closed.
• A cover for the cylinder, also made of stainless-steel mesh, and with a fitting for a hose.
• A small recirculation pump, preferably a peristaltic one.
• A timer.

Process

The destemmed and crushed grapes enter the filtering cylinder through the hose and the fitting, filling it. The liquid grape juice filters into the tank until the volumes are balanced. The grape juice should exceed in 1 or 2 cm the cylinder cover. A separating piece is put to leave space from the top of the cylinder cover to the bottom of the tank cover, about 10 cm. Then, it is covered and left to ferment. It is not uncovered until fermentation is finished, or until pressing is wanted. When the samples indicate that the fermentation is finished and we do not want to macerate more, we run off, we drain the wine, and we press.

Stabilisation

Using the conventional method, the tartaric stabilisation of a wine is based on causing the crystallization of the excess of potassium bitartrate in wine and eliminate it. The process consists in lowering the wine temperature below 0 degrees (it is usually calculated by taking half of the alcoholic strength minus one). When the wine reaches the desired temperature, it is put in an isothermal tank. While the potassium bitartrate precipitates, the conductivity drop is controlled. When no more potassium bitartrate precipitates, the conductivity stays constant. The wine is stable, and now it is filtered to eliminate any crystal remains. However, it must be said that, before cooling the wine, the wine is cloudy because of the colloids and proteins which are in suspension, and which come from the fermentation of the grapes, so it needs to be cleared (putting a clearing agent in it, such as bentonite, casein, egg albumin, gelatine, or others), and then it is passed through a thin filter. The basis of the stabilisation using the Verdú-Escuder method consists, not so much in eliminating the excess of potassium bitartrate, but in inhibiting its crystallisation. The process consists in stirring the wine slightly with a small suction pump at the top, and introducing it through the bottom to a tube with microholes. This makes the wine come out strongly, sweeping the base of the tank and creating a circular movement towards the upper part. We do this movement for 15 minutes twice a day, and 3 months later approximately and confirmed by conductivity tests, the wine is stable. The wines stabilised by using this method and bottled from 2012 show us that they do not have any potassium bitartrate precipitation.

Advantages of the new method

In contrast with the conventional method, when at least three filtrations, a clearing and a cooling are carried out, and in each one of these actions not only the potassium bitartrate is eliminated, but many particles provided by the grapes, with this stirring process we keep EVERYTHING that the wine contains. We keep all the tartaric acid, the potassium, and the huge number of other molecules and quality factors which have been added to the wine through the constant and soft movement, and which give it consistency and volume in the mouth.

Materials if carrying out the stabilisation in a tank

The same fermentation tank without the filtering cylinder

Process

We fill the pressed wine tank, we set the timer and we start with the intermittent movement for 15 minutes twice a day and for 3 months approximately.

Materials if carrying out the stabilisation in a barrel

• A barrel.
• >A stainless-steel tube with microholes at the bottom and a conical adaptor to put it in the barrel.
• A small pump with two flexible tubes.
• A “bag-in-box” bag.
• A flexible tube that connects the bag-in-box to the upper part of the barrel.
• Un timer.

Process

We assemble the barrel so that the tube that goes to the pump is connected at the top of the barrel. And the tube coming from the pump is inserted to the tube with microholes which is already put at the bottom of the barrel. XXXXXX A més connectem el bag-in-box, ple amb el mateix vi, amb un tubet flexible a la part superior de la bota. XXXXXX We fill the wine barrel, we set the timer, and we start with the intermittent movement for 15 minutes twice a day and for 3 months approximately.

Conservation and ageing

Ageing is defined as the period of time that the wine goes through between the stabilisation and the bottling. It can be carried out in different containers. In stainless steel, such as in tanks, in wood, such as in barrels, in glass, such as in demijohns or bottles, and more. After stabilisation, the wine still contains microparticles from the grapes pulp. These molecules cloud the wine, and we want it to be clear when bottling. In the case of ageing in barrels, the wine, which is at rest, precipitates all these particles, which fall and accumulate at the bottom of the container. For this reason, and regardless of the winery and its philosophy, normally 4 transfers are carried out in the first year, and 3 in the second year. It is done very carefully emptying the clean wine and eliminating the remains of the bottom. We must think that a part of the wine content is lost in each transfer. The ageing process last for many months, and the barrel has pores through which the wine evaporates, the barrel empties, and it leaves an empty space at the top. This is a problem because the yeasts or the acetic bacteria can settle there and spoil the wine. To avoid this, the winemaker must refill the barrels one by one every 15 days to raise the level at the cover level. Unlike this conventional method which tries to take out a big part of the wine particles, the Verdú-Escuder method seeks to include and dissolve in the liquid all these particles which are now clouding the wine. With the movement, the macromolecules are cut into micromolecules which dissolve in the wine. The purpose is to use the maximum of what the grapes have provided in this process. We take advantage of the fact that we have the stabilisation system, that is to say, the pump which sucks the wine from the top and pushes it to the bottom through the microholes of the tube, but now we only do it once a day for until approximately three months before the bottling of the wine. To reopen the bottles, we have the bag-in-box connected. Therefore, while the wine evaporates gradually, it enters the barrel from the bag-in-box and the barrel is always full.

Advantages of the new method

Instead of eliminating a part of the grape components, in each of the several transfers which are usually done, we include them, providing a wider variety of aromas, tastes and structure in the mouth. On the other hand, as the barrels do not need to be refilled manually, because it is already done automatically, we save ourselves a lot of work from the winemaker, and we avoid any possible creation of membranes and bad tastes because of the space with air that might be at the top of the barrels.

Materials

The same ones used for the stabilization. We need a bag-in-box for each different kind of wine. If we have single barrels, we put a bag for each one. If all of them are the same, we put a bigger bag for the whole group, and we connect all the barrels with a small flexible tube.

Process

If we have stabilised the wine inside the tank, now we put it in the barrel which is already prepared with the tube with microholes, the pump and the bag-in-box. <pNow, we reduce the mixing frequency to once a day and until 3 months before bottling, and after this, we let it rest.

Data of the first wine with no additives: “el cinquè”

The first wine that we made using this new method is from the 2012 harvest. We bottled it without filtering to avoid taking anything out.

Maceration with the skin: 25 days Ageing in oak barrel: 12 months Here you have the analysis carried out by the Vitec laboratory before bottling the wine:

• Alcoholic strength (% vol): 14.2
• Total tart. acidity (g/l): 5.10
• pH: 3.69
• Residual sugars (g/l): 1.10
• Malic acid (g/l): 0.02 (malolactic fermentation carried out)
• Volatile acet. acidity (g/l): 0.65
• Free SO2 (mg/l): 2
• Total SO2 (mg/l): 7
• Turbidity (NTU): 3,5 (normal value in bottled wines. 8-10 NTU)
• Number of yeasts/100 ml: 99
• Number of Brettanomyces/ml: No detected
• Number of acetic bacteria/ml: 1.620
• Number of lactic bacteria/ml: 5.230
• Aldehydes (ppm): 2,5 (perception in the nose at 100 ppm)

We encourage you to have a look at the Powerpoint to understand better this explanation.

Josep Lluís Pérez and Montse Ovejero