Wine Making

Here is an overview of the steps in making wine.

1. Grow and harvest grapes.
2. Remove stems and crush to release the juice. This juice is called must. If using carbonic maceration, crushing is unnecessary.
3. If making a white wine, 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 regions have regulations about how much juice may be pressed from a given mass of grapes.
4. Optionally, allow the wine to rest under refrigeration (the cold prevents fermentation). This period of maceration helps extract the maximum quantity of compounds from the skins.
5. Either induce fermentation using a yeast culture, or allow fermentation to start naturally with already-present yeast.
6. Keep the juice in a cool, food-grade container (usually stainless steel is used today, although home winemakers often use glass carboys), that has a small hole on top for the CO2 produced by the yeast to escape. (Danger: your cellar may be filled with CO2 gas, so please ensure good ventilation. It is a rare year when a cellar worker somewhere in the world does not drown after being accidentally suffocated and falling into the tank.)
7. 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.
8. Optionally, either during alcoholic fermentation or afterward, induce malolactic fermentation. Many reds and some whites undergo this process to convert sharper malic acid to softer lactic acid.
9. 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.
10. 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.
11. Many 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 must be clear and not throw any sediment to be saleable. Fining agents such as bentonite (a kind of clay) or egg whites are used to remove these suspended solids. Filtration is also used, which can have a negative impact on the quality of the wine. However, it has also made the production of slightly sweet wines possible by removing all yeast cells.
12. Bottle the ready wine. Continue its ageing in the bottle if appropriate.