Have you ever sat down to enjoy a glass of wine and wondered how such a magnificent thing came to be? Well look no further this post will put some of your absent ponderings to rest, hopefully. Let me start off by stating that wine is made in a magnitude of ways. The process this post is meant to “sum up” can differ in many different ways and at many different points. The way in which I have described the process is meant to be general rules of thumb and to help those of us who lack a heavy background in science understand the complex formalities of the actual chemistry at work.
Once ripe both red and white grapes are harvested from the vines that bore them through the summer sun and into maturity. Grapes can be harvested mechanically or by hand depending on the practices of the individual vineyard. They are then sorted to remove any underdeveloped or imperfect grapes/clusters to assure the quality of the juice.
The grapes deemed worthy to enter that years bottling are then crushed and depending on the style destemmed before fermentation. At this point in the process red and white wines take two totally different paths and will be described separately so as to avoid confusion. To further lighten the burden of trying to remember your days of high school chemistry the process of fermentation is laid out below.
The pulp of the crushed grapes destined to become white wine is pressed through a membrane to extract as much juice as possible without getting to much tannin or color from the seeds, pith, and skins. The juice is then pumped through a heat exchange or treated with Sulfur to prevent oxidation or a premature fermentation.
The settling stage is next where enzymes are sometimes added to encourage suspended solids to collect at the bottom of the tank. During this time an inert gas may be used to cover the grape juice to further protect from oxidation. The juice is then moved into a clean tank to begin the process of fermentation (A) which can last anywhere from a week to a month.
After fermentation is complete the wine is filtered again to remove any dead yeast cells or pomace particulate left in the wine. At this point the wine is either stored in stainless steel, or barrel depending on the desired style; this is also where malolactic fermentation (B) will take place.
During its time in storage/aging the wine may also go through cold stabilization where tartaric acid can crystallize and be removed from the wine in its final filtering. From there it finds its final destination home in its bottle.
Red wine gets its color from pigments found in its skins; thus red wine is fermented using skin contact. After crushing and pressing red wine begins its fermentation (A) in a large open topped tank made of wood, metal, or cement. The CO2 given off during fermentation will continually push the crushed grapes or “must” to the top of the vat forming a cap. This cap must be constantly kept wet by either punching the must down into the juice or pumping the fermenting juice over it.
When fermentation is complete the juice will be drained from the must and racked into barrels. At this time the must that remains will be pressed to create press juice. This juice is much higher in tannin and structure and may be added later to give the finished wines depth.
If the red wine is being aged in barrels malolactic fermentation (B) will again take place. While in the barrels the wine will need topping off to compensate for any evaporation and prevent oxidation. Racking may also take place at this stage to further clarify the wine. Racking is the process of moving wine from barrel to barrel to help get rid of sediment and aerate the wine while aging.
Before bottling reds are further clarified by adding a fining agent to get rid of any left-over solids and possibly filtered one last time to ensure the stability of the wine before bottling. And there you have it friends, in its simplest form how wine is made. A process that has inspired and baffled men for ages; let’s all be thankful they finally got it right.