Wine making
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The following is a list of the basic steps involved in wine making:
- Grow grapes until ripe. Ripeness can be judged using the Brix scale, or by waiting for the grape's moment of "physiological ripeness" by taking into account the ripeness of the seeds and skin of the grapes, based on color or other attributes.
- Remove stems and crush to release the must. If using carbonic maceration, crushing is unnecessary.
- For white wines, press the juice off the skins. The juice that comes out from the pressure of the grapes alone is called "free-run" juice, and is generally saved and fermented separately. Some appellations and regions regulate how much juice may be pressed from a given mass of grapes.
- Optionally, allow the juice to rest under refrigeration, to prevent fermentation. This period of maceration helps extract the maximum quantity of compounds from the skins.
- Induce fermentation by introducing a yeast culture. Never allow wild yeast to ferment the wine naturally as this can ruin the fermentation.
- Keep the wine in a cool ventilated location, in a food-grade container that has a way for the CO2 produced by the yeast to escape (which is one reason for the ventilation). Home winemakers often use carboys; commercial fermentation of larger amounts of juice is done in stainless steel containers.
- While fermentation is active in a red wine, the seeds and skins will rise to the top of the fermenting vessel. This "cap" needs to be kept wet with fermenting juice for maximum extraction. To achieve this, punch down the cap at regular intervals.
- The acidity of the fermenting must is periodically measured to determine when fermentation is complete.
- Separate the juice from the skins (if this is a red wine), seeds, and fruit pulp. This may be done at various points, usually at the end of tank fermentation.
- Optionally, either during alcoholic fermentation or while in storage, induce malolactic fermentation. Many reds and some whites undergo this process to convert sharper malic acid to softer lactic acid.
- When tank fermentation is complete, "rack" (draw off) the wine from the settled yeast cells and sediment which is called the lees. Or, leave the wine with its lees to age sur lie. Most winemakers add sulphur dioxide to prevent both oxidation and any further fermentation.
- Most solids suspended in the wine will settle out on their own, given a little time. However, this could take months, and does not always result in a crystal-clear wine. Commercial wines sometimes use fining agents such as bentonite (a kind of clay) or egg whites to remove these suspended solids. Filtration is also used to remove solids from wine and to remove all yeast and some bacteria cells.
- Wine is transferred to storage tanks (or for some wines, oak barrels, to allow the oak to impart additional flavors to the wine). Store the wine for anywhere from three months to several years.
- Optional: blend wines from different areas, years, and grape types. If producing a wine designed to meet a certain appellation, check local regulations for what is allowed.
- Bottle the ready wine. Continue its ageing in the bottle if appropriate.
If you wish to make a country wine from ingredients other than grapes, the procedure is similar. Usually refined sugar or another sweetener is necessary; add it before fermentation begins.