4.1.5.e What types of extraction are possible?

Pumping over

Pumping over is the most common practice for extracting phenolic compounds. It consists of removing the must from the bottom portion of the tank and then pumping it back over the skins. The objective is to spray the marc cap with "new" juice to replace the juice in contact with the marc. A significant concentration gradient is created which allows more compounds to be extracted.
Regular pumping over ensures that all of the marc is included in the extraction process.
The volume to be pumped over depends on the must density, the vat size and the quality of the raw material. Pumping over can be done with or without oxygen. Generally, two pumping-overs per day are carried out and range from the equivalent of 5 to 100% of the volume of juice in the tank. However, the number can be increased while keeping the same pumping over volume, this is called fractional pumping over.

Punching down

Punching down is an ancient practice that consists in pushing the cap into the vat in order to break up any preferential must pathways and increase extraction. In organoleptic terms, punching down (if done at the right time) brings more volume and richness (giving more body to the initial palate) by enabling better extraction of skin tannins and polysaccharide compounds. If performed too late, the extraction is intensified and also brings seed tannins. It is important to be vigilant at this stage because the wine could become harsher and more astringent. This obviously depends on the grape variety and the quality of the raw material.

How many punching downs per day and using what method?

Punching down can be carried out once the marc cap has formed, that is to say when the density has decreased by about fifteen points. One to three per day can be performed. Below 1030 density, increased vigilance is required because the extraction becomes much more intense.
It can be done manually using a pigeur which is a stainless steel rod with a paddle on the end, or using an automatic punching down system, which is much more convenient for larger vats. However, if the vat is closed, the access trap must be big enough for this type of machine to pass through.

**Can it be combined with pumping over?

Fermentation needs oxygen, which is provided during pumping over. It is possible to do a punching down in the morning and a pumping over in the afternoon for example. Punching down breaks up any preferential paths in the must cap and the act of pumping over then allows new paths to be created.

Rack and return (délestage)

The rack and return procedure improves the exchange between the liquid phase and the solid phase (the marc) in the vat. To accomplish this, the juice is transferred to a buffer tank, then sent from the buffer tank over the marc cap with a pump with a high enough flow rate to completely destructure and submerge it. The marc cap then gradually reforms in the vat. A period of time between emptying and refilling is sometimes permitted to allow time for the juice present in the pomace to drain.

This method allows a fairly significant extraction of compounds. Other alternatives exist regarding methodology, particularly the juice's return to the tank using a tourniquet, and are generally gentler.

On what type of wine should it be used?

Used as defined here, it is a fairly powerful extraction method. It should therefore be used sparingly and only on grapes that have the potential. There are three questions to ask yourself when choosing whether or not to rack and return:

• Are the grapes sufficiently ripe? It is important to avoid its use on plots that are only moderately or insufficiently ripe. The reason being that with poor seed ripeness, this is likely to result in the extraction of poorly polymerized tannins that can be very harsh and bitter on the palate, as well as a possible appearance of vegetal aromas. Moreover, if ripeness has not been reached, the seeds will not be sufficiently lignified, which facilitates the extraction of their tannins.

• Are the grapes healthy? In the event that the harvest is botrytized, high extraction never improves the quality of the wine. Similarly, grapes that have undergone significant water stress, resulting in particular in the presence of withered berries, racking and returning is not recommended.

• What is the desired final wine profile? Racking and returning often leads to more structured wines, so it should be avoided for lighter wine profiles and/or grapes that do not have the appropriate potential, at the risk of extracting less qualitative compounds.

**At what stage should it be carried out in the fermentation process?

Two rack and returns are possible during alcoholic fermentation. One after the formation of the marc cap, i.e. at a density of approximately 1075. A second one can be carried out 48 hours later, which usually corresponds to a density of around 1040. Below this density, racking and returning is less selective and the risks of extracting less desirable compounds become significant.

Infusions

Infusion is based on the same principle as tea bags, the bag here being the marc. The marc cap is submerged throughout the fermentation and until the end of the post-fermentation maceration. It is never in contact with air. This is a very gentle extraction where the juice is renewed only by pumping or by doing nothing at all, depending on the case.

**In what instances is it suitable?

This method is well suited to various profiles:

• Ripe grapes with high potential alcohol

• Grape varieties that have a high tannin content such as Petit Verdot or plots with a rustic tannin profile

• Profiles where desirable compounds can be extracted with very little effort

**How is it implemented?

Implementation is difficult because it requires an immersion system such as a grid to keep the marc cap submerged.
Alternatively, it is possible to use an ovoid container with the possibility of pressurization so as to immerse the marc using the CO2 emitted during fermentation.