The science of wine making describes how wine is made. It is a practice with the perfect balance of tradition and innovation. We will start with the vineyard and take you all the way through the winery. Hopefully we will do this without offending any master winemakers.

The Vineyard Any experienced winemaker spends most of their time in the vineyard. Vineyards influence the final product of wine more so than winery manipulations and procedures can ever accomplish. Careful attention should be given to both climate and soil conditions before planting wine grapes. Particular varieties excel only in specific kinds of climate and soil conditions.   Climate A regions climate greatly affects the types of varieties that are available for a wine producer. At the University of California, Davis, viticulture researchers divided California into 5 regions according to the number of degree days. Degree days are a way of measuring the cumulative amount of heat absorbed by the plants. The number of degree days required by a vineyard varies with the type of variety grown. The primary purpose of this system is to give grape growers a accurate estimate of when they can begin to harvest the grapes. Below is a table that describes the characteristics of wine produced depending on the climate the grapes are grown in. WARM CLIMATES COOL CLIMATES high sugar low sugar low acidity high acidity low color high color low flavor high flavor high yields low yield Soil The soil is a factor that can easily be overlooked by a grape grower. It supports the vine and acts as a reservoir for holding nutrients and water. The water holding capacity of the soil strongly affects the final flavor of the wine. Propagation Grape vines are typically purchased from nurseries where they have already been grafted to prevent phylloxera infestation. New vines typically will not produce significant yields of fruit until the 3rd or 4th year! This is a very important point in terms of risk assessment and a business point of view. If the crop is lost via fire, flood, or some other natural disaster or accident, the winery would be put back 3-5 years without any income. This makes the vineyard an extremely high-risk asset because of the substantial amount of consequences that result from its loss (probable foreclosure). Vines typically have a useful life of about 20 years before they are discarded. General Winery Operations Harvest The vine cycle depends largely upon the regions climate. In California, the vine cycle begins around April 1st when new shoots elongate during April and May and the vine flowers around May 15th. Tiny berries begin to grow but remain green and hard until about July 15th. Veraison begins then and the berries begin to develop color and to soften. Fruit is usually harvested around September 15th (see photo to the right). However the harvest date is largely dependent upon the variety, the location, and the weather. Before wine is removed or harvested in the vineyard, the amount of sugar in the grape must be measured (degree brix). A couple of common methods of measuring the sugar level in a grape are a refractometer (refraction of light) and a hydrometer (density of juice). Furthermore, the acidity level must also be measured before harvesting the grapes from the vine. Two common methods are titration (grams of tartaric acid per 100 mL of juice) and pH. Once the sugar is measured, the wine maker can estimate the alcohol concentration of the finished product. These methods have all been developed to aid the vineyard in giving the winery the best possible grape for the desired purpose. Final Alcohol Concentration = X(Degrees Brix) x 0.55 Crushing The grapes are now crushed to make the juice accessible to the yeast. Crushed grapes are called the must. The must is made up of 80% juice, 16% skins (wine pigment), 4% seeds (tannins = wine flavor and aging characteristics). Therefore, controlling the amount of contact achieved between the juice, skins, and seeds is critical to the flavor, color, and overall final product of the wine.  Additions Several additions may be made to the must before pressing it. SO2 is commonly added to inhibit oxidation and kill undersireable micro-organisims. However, if the winery chooses to put SO2 into their wine, US law requires the winery to write "contains sulfites" on the bottle label. Although in most cases the winery is aware of the amount of sugar in the grapes they are crushing, sometimes winemakers wish to add sugar to the must to either enhance flavor or raise the alcohol concentration. The act of adding sugar to the must after crushing is called chapitalization. Chapitalization is illegal in California and in southern Europe. Adjustments may also be made to the must’s acidity. Pressing Pressing is done to separate the skins, seeds, and any other non-juice must item from the juice. There are several different types of presses used in the winery industry. Some of the more popular ones are the screw, membrane/bladder, moving head, and basket presses. The basket press has a piston which pushes the fruit down in a cylinder. The moving head press is similar to the basket press except it presses horizontally as opposed vertically. Racking Racking is the process of transferring juice or wine away from the settled lees. Titration and centrifugation are alternative means by which a winemaker could use instead of racking. Fermentation Fermentation is typically initiated by adding 1 to 2 percent by volume of cultured yeast to the juice or must. Although there are many different kinds of fermenting vessels used throughout the global wine industry, in the United States, most modern wineries use stainless steel tanks. The fermentation process is regulated closely by managing the temperature of the vessel and yeast. This requires that refrigeration jackets or heat exchangers be installed on the fermenting vessel. Aging The most common way wine was aged in the past, and the tradition persists to this day is via barrels. Barrel aging is typically used for red wines and adds vanilla, spicy, and sometimes smoky flavors to the wine. French Barrels French oak is the primary type of wine barrel used today staying in line with a strong European wine making tradition. French oak is the barrel of choice for chardonnay. France uses somewhat of an appellation system that designates the forest from where the wood was purchased to make the barrel (i.e. Limousine forest) and hence some wineries specify not only the country but also the specific forest location of the wood that used. Due to the long lasting reputation and high labor costs, French wine barrels run between $700 and $800 per barrel. American Barrels Although new to the world wine making industry, American oak wine barrels on a number of occasions have been proven to be capable of producing high quality wines and thus their usage is on the rise. American oak is the barrel of choice for Australian Shiraz because of the pleasing distinct flavors that complement that style of wine. American barrels are less expensive than the average French barrel ranging between $250 and $300 per barrel. The current trend is that as the price of wine barrels increase the usage of American oak barrels increases as well. Because American barrels have lower labor costs and are relatively new thus not having a long consistent history, they are substantially less expensive than French barrels. Combination Barrels Outside of the French barrels made by the French and American barrels made by the Americans, there are Americans who make barrels using imported French wood and French who make barrels using imported American wood. The prices vary slightly from the barrels described in the two sections above. The average useful life of both American and French barrels are roughly 5 years. However, innovations such as inner stay oak slates or carving away a few layers of wood inside the barrel can extend the life of a barrel up to 10 years. Furthermore, all barrels should be topped off roughly once a week to eliminate void air space and thus helps prevents the formation of VA. Blending Wine coming from different must batches, varieties, vineyards, fruit maturities, and wine making treatments are sometimes blended by the winemaker in order to produce a more uniform final product. Fining Fining Agents Egg white Gelatin Casein Bentonite Various enzymes Fining Agents are used to take out undesirable particles, which tend to make the wine "hazy". By fining the wine, the wines clarity is greatly improved. This is critical to white, blush, and sparkling wines where clarity is highly important to the average consumer. Filtration Wine is then filtered to further clarify and stabilize the wine. Bottling The last step before the wine leaves the winery is bottling. Most wines are aged in the bottles for a few months up to a few years depending on the wine and the winery. However the general steps listed below, ring true for most winery operations. Transfer wine to a holding tank Treat with SO2 to prevent oxidation Turn bottles upside down and rinse with hot water or sparge with nitrogen. Fill bottle with wine and insert the cork immediately Apply label and place on racks for bottle fermentation or put them directly into boxes or cases. Stored allowing bottle aging to begin (3 months (white) to 2 years (red)) Continue to monitor the living wine to detect in instabilities.