Winemaking Process

 

Let’s start with the obvious basis for wine which is the grape. As a note, some areas produce wine from other fruits such as apple, pear, etc. I will not discuss these as I want to keep this to the more traditional wine type. There are over 600 varieties of grapes. I will touch on only a few because these represent the majority of the wines and they are the best suited to winemaking. Each year when the grapes are grown, there are factors that affect the quality of the grapes themselves. These include temperatures, rainfall, soil conditions, humidity, sunlight, topography, etc. Keep in mind that these factors affect different varieties of grapes, well differently.

 

Climate has an enormous effect on the development of the grape. “Remember you can’t fool Mother Nature” – well this applies here. The climate effects like temperature variations, sunlight duration, rainfall amounts and their frequency all go into the success or failure of the vintage. These factors also dictate the type of grape to be grown. Cooler climates tend to be lower in alcohol and higher in acidity than hot climates which tend to be less refined. The mean daily temperature needs to be between 60 – 70 degrees F. Winters need to be cool enough to allow the vines to revitalize, but not too cold (below 5 degrees F) to risk freezing. Rainfall is also important. A vine needs at least 20 inches of annual rainfall. Obviously irrigation techniques can mitigate insufficient rainfall, but only to a point. Hence I wouldn’t plan my vineyard in the Arizona desert.

 

The terrain aspect which includes the composition of the soil, the drainage in a particular area, the amount of sunlight an area receives, the temperature variations during the growing season are what the French call terroir, and are highly influential in the development of the grape and hence the final product. Here too, the type of grape needs to match the particular terrior. Winemaking is clearly an art as well as a science. It is becoming however, more of a science in terms of the technology used to predict and help control grape production. Vineyards typically employ high resolution electromagnetic soil surveys and elevation mappings to identify higher yielding areas for planting. The winemaker cannot control the environment such as amount of rainfall, duration of sunlight, slope of the land, etc. He can however mitigate to some extent negative factors which will increase either production or quality. For example, if the land receives too little sunlight, the grapes will not ripen because the proper amount of photosynthesis (the process by which plants convert carbon dioxide and water into sugar and oxygen via chlorophyll and energy from the sun) will not take place. The design of the vineyard comes into play during planting and can affect the final outcome. The orientation of the vines, the distance between rows, the distance between the vines all come into play to affect the grape. Vine-growers constantly monitor the sugar content of the grapes (it is the sugar which ferments into alcohol) by using a portable spectrometer.

 

The skill of the producer becomes the dominant factor in the creation of wine after the grapes have ripened. The producer needs to decide when to harvest the crop. The producer is typically measuring acid and sugar content of the grapes to determine the point of maximum ripeness. Grapes are picked by machine or by hand. The latter is used in the more expensive wines so that pickers can make on the spot decisions as to which fruit to pick. The majority are done by machine. The specific grape is also considered relative to timeliness of harvest. Merlot grapes are less forgiving and will lose quality if left too long on the vine. Cabernet Sauvignon grapes are more tolerant.

 

After harvesting, the grapes are crushed to emit their juice. The grapes are crushed in a large steel crusher. Of course the age old stereotype of bare-footed women stepping on grapes in a large vat is typically not done by modern producers – although I’m sure it exists someplace, albeit the infamous “I Love Lucy” episode. White wine grapes are actually pressed to emit their juice which is kept in a chilled holding tank until the sediment drops to the bottom. The juice is then put into a stainless steel fermenting tank where yeast is added. Fermentation takes approximately 10 to 30 days at a temperature of 25° C to maintain the volatility of the yeast. Some white wines like Chardonnay are fermented in an oak barrel to impart an oak flavor to the wine. Wines fermented in oak will undergo a second fermentation process called malolactic conversion where the addition of lactic acid bacteria converts the malic acid to lactic acid which gives the wine a richer and more “buttery” taste. Red wine grapes are crushed and the resulting crushed juice contains various amounts of pulp, skin, stems and seeds (called must) that stay in contact with the juice for a few days to produce some of the wine’s characteristics such as color and flavor. Sulfur dioxide is usually added to inhibit the formation of bacteria. After this soaking process, the pressed grapes, pulp, etc (must) is sent to large stainless steel fermentation tanks where sugar and yeast are added to initiate the process. After 2 – 4 weeks, the chemical processes produce carbon dioxide and ethanol or, alcohol. The higher the sugar content, the longer the fermentation process. The wine is then stored in either stainless steel or oak barrels for up to 3 years, to age, depending on the type of wine. Aging in an oak barrel imparts an oak flavor that is prevalent in some wines. It is then bottled, corked and sold.  If sparkling wine is made, carbon dioxide is added to white wine at the time the wine is bottled. Of course the French insist that to be called Champagne, the wine must have come from the Champagne region of France.

 

Although each producer tries to produce the finest bottle possible, factors beyond his control enter into the equation. I am referring to the growing season specifically. Now let me state that even with fantastic conditions, the producer can still ruin the process, the growing season will dictate the success of the product. Obviously this is geographically dependant. Typically these are rated by various experts such as Robert Parker, Wine Spectator, etc. They range from Outstanding (100 – 92 points) …. Basically, you can’t make a silk purse out of a sow’s ear. A quality producer can mitigate a not so great year. Also many producers blend varieties of grapes to produce their product. Read the labels – more about this in another section.

 

When vintages are rated, they are done so geographically. So for example, Wine Spectator might rate 2003 Chardonnay vintage of Sonoma as a 88 while rating the 2004 vintage as a 99 for the same region. Now the particular wine producer through his ineptness can take a great vintage year and screw it up just as that same wine producer can take a marginal vintage and improve it somewhat through his abilities at managing the vineyard. Nature however is the dominant player when it comes to the growing of the grapes. The skill of the producer is the dominant player in the wine making process.