Weather determines when harvest season begins and ends. Typically grapes are ready for harvest in California in late August or early September. Harvest season may last till November depending on the grapes.
The grapes stems must be separated from the fruit and the berries broken up. This is accomplished by using a destemmer/crusher. The stems are discarded and a “must” is produced. A “must” is a combination of juice, seeds, pulp and skins. Red wine gets it color, flavor and “tannins” from the grape skins. Tannins allow red wines to become more complex as they age. The polyphenols of the tannins allow this to occur. White winemaking is different in that the seeds and skins spend only a few hours with the juice, which is commonly known as “free-run”. The skins are then “press-juice” to extract the remaining juice. The “press juice” and “free-run” are filtered in preparation for the fermentation phase.
In order to start fermentation yeast is added to the juice. It is this process which converts the natural sugars into alcohol. Oak or stainless steel tanks may be used during the fermentation and aging process. Malolactic fermentation may also be initiated to convert the tart malic acid found in fruit to softer lactic acid. This process is referred to as the second fermentation to obtain the desired flavor. The fermentation process may last three days to three weeks depending on the wine.
As stated wines can be aged in oak barrels or stainless steel tanks. Red wines are aged for one to two years. White wines can be aged anywhere from one week to a year. Sparkling wines depending on the method used may be cellared for two years or more. Wines may also be blended with other wines to create different characteristics and produce a different flavored wine.
This process allows the wine to be stabilized and filtered before bottling. To make the wine clear egg whites or gelatin are added to remove any astringent substances or proteins that can make the wine cloudy or impact its flavor. Sulfites may also be added to prevent oxidation and bacterial spoilage.
(ONLY FOR SPARKLING) Sparkling wines are made from white and red wines. Selecting a base varietal or blend produces sparkling wines, and then a “tirage”mixture is created. A tirage mixture is when the some of the base wine plus yeast and sugar are mixed up. This tirage mixture is then added to the base wine causing this to ferment in a sealed container. The sugars convert to alcohol; the by-product of carbon dioxide is trapped inside, which produces the finished wines effervescence.