This will likely be wordier than most of my entries, but it’s laying out some (bare bones) fundamentals, so bear with me.
At its most basic level, wine exists because of fermentation: yeast + grape juice = alcohol, carbon dioxide, and a little bit of heat.
Wine stops fermenting on its own eventually because alcohol is toxic to yeast (kinda sad that the little guys produce the very material that winds up killing them…) The yeast gobble up most of the sugars and nutrients in the grape juice, until they've made enough alcohol to kill them off. (As a rule, white wines are less alcoholic than reds and alcohol by volume in finished wines tend to range between 11%-this is really low- and 15%-this is really high and usually only happens in fortified wines- more on those later.)
Alcohol content can be controlled by the winemaker by stopping fermentation before the yeast eat up all of the sugar and nutrients, leaving a lower ABV (alcohol by volume) but the wine will contain residual sugar. If a wine is allowed to ferment till it finishes on its own (called fermenting to dryness because it means it has used up all the sugar, and dry = not sweet) and still has a really high alcohol content, this is likely because the grapes were really sugary to begin with and probably involved the use of a yeast strain that is more resistant to alcohol.
Most winemakers harvest their grapes once they know they contain a sugar level that will give them the eventual alcohol concentration (and residual sugar content) that they want for the type of wine they’re making.
Winemakers take the fruit into the winery and depending on the type of wine they want, either crush the fruit, or immediately press the juice out of it.
- White wines are often immediately pressed in order to keep bitter components (tannins) from the seeds and stems (most high quality wineries remove stems first- but larger bulk wineries often don’t) and color from the skins from having contact with the juice. This is the point at which you could choose to make white wine or rosé from grapes with red skins- just press immediately, keeping the skins from transferring their color to the juice! (that’s maybe a little overly simplified, but you get the gist.) There are some grapes used to make white wine that are white in color to begin with, such as Chardonnay and Riesling- but in theory you could make white wine from any grape.
- For red wines that you want to be complexly flavored and deeply colored, winemakers often crush the fruit first, letting it have contact with the skins and seeds (the number of hours depends on the winemaker’s preference.) Then, they press the juice out.
Then (this is the abridged version here,) they add the yeast and let it ferment (either till dryness or till there’s the desired amount of sugar left- in which case they have to stop the fermentation manually.)
Once it is done, they drain the wine off, leaving the dead yeast cells and other sediment behind, filter out remaining solids or anything that could leave it looking less than clear, and age it-either a little or a lot (in oak or stainless steel.) Before bottling, they’ll filter it again using a really, really, really, really, really fine filter (we’re talking fractions of microns here) to make sure there are no yeast or bacteria cells left in the wine and then bottle it!
Usually wine is aged again in the bottles before it is ready for drinking. Some wines (especially the fancy ones sold at auctions) can be aged for many, many years. Others are meant to be opened and enjoyed within a year or two. I don’t own any super schmancy wine, so I generally try to drink mine up within a few years of the date on the label.
That’s it- the Reader’s Digest version of how wine is made- from berry to bottle…
Questions are welcome in the comments!
Did you know?
Grapevines have been intentionally cultivated by humans for close to 8,000 years and originated as we know them near the Black Sea. The discovery of wine was probably an accident- someone left some ripe, juicy grapes out too long and the yeast cells present in the air or on the skins did their thing.