What is meant by Winery Practices

What is meant by Winery Practices

What is meant by Winery Practices
"Cellar practices" are all those operations that accompany the winemaking process until the wine is obtained. Each stage of winemaking, starting with the crushing/stemming and ending with the bottling of the wine is preceded or followed by racking, riddling, filtering and other operations that help transform the fermented must into the finished wine. Let's see which ones are the most important and recurring.

General cellar practices
The contact of wine with deposits produced by fermentation, such as yeast cells, residues of grape skins, pulp and seeds, more or less soluble salts, such as potassium bitartrate, and in red wines, from coloring substances and polyphenols, can be the cause of alterations and defects. Moving wine from one container to another, to allow separation of lees that settle to the bottom, involves racking. The number and frequency of racking changes depending on the type of winemaking undertaken. Red wines are much richer in extractives, so the number and frequency of racking is greater than for white winemaking. Decanting must always be done perfectly, as any mistakes could compromise the quality of the wine. In fact, racking is an elementary method of making the wine clear, but it could also lead to alterations in the wine by triggering undesirable oxidative or fermentation phenomena, for example.


Filling cap
During maturation in barrels it may happen that the volume of wine in them does not completely fill them, due to evaporation that may be induced by temperature changes, or due to phenomena of expansion of the wood of the vessels. In contact with air, the wine may be subject to oxidation or development of aerobic microorganisms, and so the barrels must be filled with the same wine in order to keep them full and free of air at all times. This can be easily achieved by using filler caps, which are inserted into the bung (top opening hole of the barrels). The filler cap consists of a small glass coil equipped with a compensation tank that holds a small amount of the same wine present in the barrel. When the volume decreases, some of the wine goes down into the cask, keeping it perfectly filled.

During its stay in the cask, due to the different expansion of the vessel and its contents as the temperature changes, the wine may overflow from the bung. I these cases, the vessels must therefore be drained. The riddling stopper makes it possible to avoid this risk as well, because its special shape makes it possible to keep the level of the wine constant, perfectly bridging the vessel.

During fermentation, the multiplicity of substances in the must lead to chemical reactions of various kinds with continuous changes in composition and obvious instability, which in turn leads to the formation of solid residues and veiling that are not always acceptable in the finished product. Some winemakers choose not to subject the wine to any filtration so as to leave the wine's array of aromas intact without affecting its quality. Within the generic definition of filtration fall practices such as the clarification, blanching and polishing of wines, all operations that involve separating the solid phase from the liquid phase, using an interposition medium that is permeable to the liquid, but not the solid, also involving in many cases the use of additional substances, such as floculants or coagulants (bentonites, gelatins) that could compromise the genuineness of the wine. Filtration is generally performed both after alcoholic fermentation to remove lees and possibly after refrigeration or pasteurization or before bottling.

Filtration techniques
Depending on the grain size of the particles to be removed, filtrations can be coarsening (removing the coarsest particles from the wine), brightening (separating even the smallest particles) or sterilizing (also retaining microorganisms while also allowing the blocking of fermentation activity of yeasts). The procedures and materials used also vary depending on the type of filtration. Deposit filtration is the simplest technique and is used to perform roughing filtrations. It involves passing the wine to be filtered through a media, usually consisting of a cloth, which retains the solid particles. Filtration with continuous flooding uses a porous media whose holes are filled with cellulose-based filter materials and rock or silicate powders. It is used to remove all lees at the end of fermentation. Filtration with filter boards employs a series of layers of board of varying thickness and different porosity. Membrane filtration employs systems consisting of filter membranes and is used to sterilize and brighten wine.

Pasteurization is a thermal process to neutralize enzymes and destroy microorganisms responsible for spoilage and disease. The name comes from its inventor, Pasteur, who devised it in the latter half of the 1800s specifically to "sanitize" wine. The practice finds widespread use today throughout the food industry but is used only for the most common wines because, while the resulting wine is enzymatically and microbiologically stable, the heat treatment causes it to lose most of its taste-olfactory properties.
Cellar practices pertaining to fermentation
This is a winemaking technique for quality white wines. The crushed grapes are left for 12 hours in contact with the skins at 5°C. Alternatively, clusters are frozen at -5°C and then pressed (cryoextraction). Both techniques yield a must that is richer in sugars and extracts, which go on to enrich the organoleptic properties of the wine.

Temperature-controlled fermentation
Especially for white wines, temperature control during fermentation is important. The fermentation process is exothermic (yields heat), and raising the temperature for white wines is to be avoided in order to preserve aromas and acidity, while for red wines a higher temperature can promote the extraction of colorants and tannins.

Use of commercial yeasts
Native yeasts (also called indigenous yeasts), that is, yeasts naturally occurring in the grapes, possibly grown on site by the producer, or selected yeasts that are commercially available and optimized to get the best results from a particular grape or for a particular type of wine, can be used in the fermentation of wines.

Folling and pumping over.
These are both techniques used during red wine making, in the presence of the so-called "cap" of pomace above the fermenting must. Fulling consists of sinking the cap into the liquid using various systems, manual or mechanical. Pumping over consists of pumping the must over the cap to keep it in contact with the liquid at all times.

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