How Wine is Made

Wine is made, basically, using only two ingredients:  grape juice and yeast.  Yeast is what causes the grape juice to become wine.  In fact, there are enough yeast spores in the air that an open container of grape juice will eventually turn into wine, but it wouldn't taste very good.  The multiple strains of yeast used for wine fermentation were cultured for that specific reason.  Similarly, strains of grapes affect the flavor and alcohol content of the wine.  Grape varieties differ by region as a result of climate, soil types, and the traditions and goals of the people growing them.

Grapes are typically harvested in late summer to mid-autumn.  The process of selecting grapes for fermentation is very particular.  For a very informative, illustrated guide to the harvesting process, check out this site:

http://www.wineanorak.com/howwineismade.htm

After harvest and selection of the best grapes, they get crushed by a machine.  This is the part of the process where you probably imagine someone stomping grapes with their bare feet.  That was the actual practice pre-technology!

The process of fermentation, or the process in which sugars are converted to alcohol, begins when yeast spores, which are living organisms, feed off the natural sugars found in grape juice.  As the yeast spores munch on sugar, they multiply drastically until all of the sugar is gone.  During this process, the sugars are converted to alcohol and carbon dioxide.  Machines are used to encourage this the multiplication of yeast spores.  The container the fermentation process takes place in makes a difference too.  Most often it's done in oak or stainless steel barrels.  This is where wine with hints of oak flavor come from.  The size of the container and temperature of storage can also affect the outcome.  Fermentation can take anywhere from a few days to a few months.  Once fermentation is complete, the yeast falls to the bottom of the container and the wine is removed from it.

Fun Fact:  Grape skins are an important part of the fermentation process when it comes to the color and dryness of the wine.  The skins of purple grapes being included during fermentation causes red wine.  If the skins of purple grapes were not included during fermentation, the wine would come out golden, like a white wine.  Additionally, skins and seeds of grapes are what cause tannin content.  Have you ever eaten just the skin of a grape?  It sort of dries your mouth out doesn't it?  Therefore, grapes with lower tannin content have been fermented sans skins.  White wines with higher tannin content come from green grapes with the skins (and sometimes the seeds) being included during fermentation.  So, by this logic, a pale wine can be made from dark grapes.  Did you know that champagne is made from black grapes with the skins removed?  The amount of time the skins are left in makes a different.  If they're left in for a short time, pink or "blush" wine is the effect.  If they're left in for a very long time, dark red wine results.

Next comes maturation of the fermented juice, or letting the wine sit in a barrel until it's reached the desired flavor.  Again, the type of container comes into play.  Maturation can take a couple weeks up to many years.

With the many variables that go into the grapes themselves, the strains of yeast, the fermentation process, and the maturation process, it's no wonder that the types of wines seems endless.





I got some of my information from the link above and from:

http://www.2basnob.com/wine-introduction.html