Once the grapes have been prepared for wine production (see grape production), they can be crushed, matured, and stored. The grapes are pumped into a fermentation vessel. For red wine, the skin is not removed; for white wine, the juice is pressed out then fermented. Typically this is done with wild yeasts from the skins, but some wineries add cultured yeast to have more control over the process. An important factor during this process is heat. Too much, and the wine tastes cooked; too little, and it tastes fruity. The grapes are also pumped and mixed during this step for color and flavor extraction. Fermentation is complete when the sugars have been converted to alcohol. This can take anywhere from 5-30 days (Total Wine and More, Fermentation). Clarification of the wine is the next step. This purifies it before storing. Some of these steps include racking, fining, filtration, and refrigeration. Once the wine is free of skin pieces, dead yeast cells, bacteria, etc., it can be stored in barrels and aged (EMAF, wine supply chain).
http://www.totalwine.com/eng/guide-to-wine/fermentation.cfm
If the winery is well-equipt (such as a medium sized), the majority of these steps can be carried out independently. Most wineries however need to outsource these activities due to lack of space and equipment. Crushing the grapes can be a difficult task because it is dependent on the weather conditions and knowing exactly when the grapes are ready. Therefore, if the winery is outsourcing this work, it is crucial that the company be qualified to handle this process properly. It is easy to pick and crush too early or too late. In addition to competency, a strong relationship between the companies is key to a successful production.
The micro and small wineries use outsource companies to crush, mature, and store their wine. The small/medium organization has the facilities to crush and mature their grapes but then stores them outside of the company. Finally, the medium winery has all of the equipment, space, and labor to accomplish these tasks but the government poses restrictions on the amount of water they can use in their area. As a result, this winery transports half of its grapes to be crushed elsewhere (Monday-Wood-Harper, 22).
On the left is a table of the amount of grapes crushed by each winery. The diagram on the right is a portion of the wine supply chain that pertains to this topic:
Vol.11-1-2010-Monday-Wood-Harper (pg. 21) Vol.11-1-2010-Monday-Wood-Harper (pg. 19)