Winemaking Process

 

Harvest

 
The time of the year every winemaker looks forward to. It begins with sampling the grapes to determine when to begin harvesting. Some go strictly by the numbers, such as pH level or Brix measurement (sugar content), while others rely strictly on taste. This generally occurs in late summer into fall depending on the grape variety and region.

Hand Picked

 

Machine Harvested

 
Much slower than using mechanized harvesting, but is much gentler on the grapes, keeping them intact until they are ready to be processed. Hooked knives or picking shears are the preferred method of clipping grape clusters which are then collected into tubs to be moved to the processing deck.
Very efficient at harvesting, but also very rough on the grapes. These machines use violent shaking motions to remove the berries from the cluster or the stem from the vine. As you can imagine, this process is prone to lots of breakage, and extra steps such as blanketing the pickings with C02 are necessary to prevent oxidation of the harvest.

Crushing

 
 
Grapes are taken from harvest and destemmed and crushed. This breaks open the grapes to create the free run juice, which makes up about 60-70% of the total juice, and exposes the internals of the grape to get ready for fermentation or pressing. The process diverts here into two paths for white and red wines

White Wines

Red Wines

White wines do not have extended contact with skins, so they go straight to the press after being crushed. For rosés there can be a short period of contact with the grape skins in order to pull some of the pinkish hue.
 
Red wines will take some time to sit on the skins, seeds, and stems, so they will go through an additional stage of maceration during primary fermentation before being pressed.

Press

Maceration

This process is done to extract the remaining 30-40% juice within the grapes. Pressing is generally done in batches such as with a traditional basket press pictured to the left, or with a continuous press that can press larger volumes of grapes more efficiently.
This is where red wine gets its color. This happens simultaneously during primary fermentation and simply involves keeping the wine in contact with the grape skins, seeds, and even the stems. It is from this contact with the skins that red wine is able to obtain its color and extract tannins.


Reds are pressed after primary fermentation
Reds go to secondary

Primary Fermentation

This is the start of making grape juice into wine. Yeast are added to the crushed grapes and/or juice. Yeast are micro organisms that are responsible for consuming the sugar in the grape juice and producing alcohol, carbon dioxide and heat as bi products. The length of this stage is determined primarily by the type of yeast and the temperature the must is allowed to get to. Cooler temperatures will prolong the process and warmer temperatures speed up the process.

Secondary Fermentation

Although the name implies an additional fermentation, it's actually most often just the continuation of the primary fermentation, but in a different tank or barrel. With sparkling wine, this process can actually take place in the wine bottle. This process is named after the region that just about everyone associates with sparkling wine, the Champagne method.

Bulk Aging

Bulk aging is easier to manage than aging in bottles. Reds generally benefit more from this than whites, which do not require as much time to mature and are able to be enjoyed younger. A winemaker usually ages wine in oak barrels. These semipermeable containers enable the wine to slightly oxidate, softening harsh tannins, as well as enhance some aromas and color.

Fining

This process primarily removes insoluble particles that are present in wine such as dead yeast, tartrates, proteins, bacteria, grape skin, pulp, etc. Adding various substances aids the winemaker by removing soluble substances such as polymerized tannins and proteins which are not able to be filtered out and can cause haziness in wine.

Filtering

An optional step, this process removes the solid particles (sediment) or microorganisms (yeast) from the wine. Plate and frame filters are very common for this and push wine through cellulose pads to perform this task. However, some winemakers prefer not to filter their wine, in fear that flavors, color, or other positive characteristics would be filtered out of the wine.

Bottling

The final stage of the winemaking process, and the step every winemaker looks forward to. There is no set method of getting wine into bottles, but it is generally performed with some sort of mechanized equipment. Wine is usually pumped into a bottler which then dispenses a set amount of wine into bottles. Corks or screw caps are then applied to complete the seal and finish the bottle.