Working by Hand (Viniculture)

The history of winemaking in California goes back to 1779 when Franciscan monks, under direction of Father Junípero Serra, planted vines at the Mission San Juan Capistrano. Today winemaking in California is considered world-class and state-of-the-art, with the latest in technology commonly used in wineries both large and small. As a result, California wine quality has never been better.

The Four Types of Wine

Table Wines

Can be white, rosé, or red in color, and can also be dry or sweet in varying degrees with residual sugar. Table wines range in alcohol content between 7 and 16% by volume. Remember that the TTB (Trade and Tax Bureau) allows for a 1.5% leeway. 

Sparkling Wines

Wines with CO2 in the bottle after fermentation. Sparkling wines are made with a number of different techniques which will be explored below. Alcohol by volume ranges between 11 and 14%. 

Fortified Wines

Are made by adding neutral spirits (i.e. vodka or brandy) to the wine for the purposes of raising the alcohol level of the finished wine. More often than not fortified wines are sweet in style and have between 14 and 24% alcohol by volume. Internationally, fortified wines include Sherry, Port, Madeira, Marsala, and others. There are California wines made in these same styles. However, per international trade laws, European place names cannot be used. 

Aromatized Wines

Are produced by adding mistelle (sterilized grape juice) that has been infused with herbs to wine fortified to have a finished alcohol level of between 15.5 and 20%. Vermouths are the most common aromatized wine. 

The Basics of Fermentation

Insert diagram of the grape

Grapes are made up of 75% pulp, 20% skin, and 5% seeds. Pulp is mostly water, but also contains sugar, acids, vitamins, and other compounds. 

Grape Skins 

  • Tannins: Bitter and astringent flavors in red wines. Tannins also provide needed structure that allows red wines to age. 
  • Color or pigment: Color in red wine is derived from pigments in the grape skins. Winemakers use any number of different methods to extract color from the skins before, during, and after fermentation.  
  • Flavor: Each variety provides a distinct set of aromas and flavors, most of which are derived from volatile compounds from grape skins. 

Grape Pulp

  • Water: A majority of the pulp is water. 
  • Sugar: Sucrose and fructose are present in the pulp and increase as the grape ripens. 
  • Acids: Tartaric, malic, lactic, and citric acids are naturally present in grape pulp. Acidity levels diminish as grapes ripen
  • Seeds/Pips: Contain phenols which can add bitter flavors to the wine.

White Winemaking

*Insert diagram of the white winemaking process

Harvest

White grapes are harvested at a predetermined time with respect to ripeness, sugar and acid levels. The riper the grapes, the riper the fruit flavors in the finished wine, and the higher the alcohol level. Harvesting is done by hand or machine. Hand-harvesting is labor intense, costly, and used for premium wines or when the hilly topography of a vineyard makes machine harvesting impractical. A majority of harvesting in California wine regions is handled by machine. 

Sorting

As winegrapes are brought into the winery, they are sorted to remove damaged fruit as well as MOG (material other than grapes). Sorting can be done by hand or use of optical sorting machines. 

Crushing and Pressing

Grapes are then either crushed and pressed, or pressed in whole clusters depending on the style of the finished wine. Whole cluster pressing is usually done in a bladder press or pneumatic press. It’s a gentler process and retains more subtle aromas in the wine.  

Skin Contact

In red wine fermentation extended contact between the must and the grape skins to extract color, flavor, and tannin is common practice. Skin contact in white winemaking is generally limited to avoid bitter phenolic compounds from being formed as the wine ferments. However, certain styles of wine such as orange wine require extended skin contact by definition. 

Settling of Solids

Once the pressing of the grapes is completed, the must (juice) is kept chilled for at least 24 hours to allow the solids to settle out of solution. The juice can also be clarified by filtering or use of a centrifuge. It should be noted that some winemakers deliberately allow the must to oxidize and turn brown before fermentation. This process is called hyperoxidation and prolongs the wine’s potential to age in the bottle.

Fermentation

After settling, the must is readied for fermentation by adding a cultured yeast. If ambient or native yeasts are used, the must is allowed to warm up to the temperature needed for fermentation to begin.  

Choice of Yeast

The winemaker chooses between using a cultured yeast or the native yeasts present in the vineyard where the grapes were grown. Cultured yeasts result in more predictable, easier to control fermentations. Native yeasts provide a different range of different aromas and flavors, but also increase the possibility of a stuck or problematic fermentation. 

Fermentation Vessel

In white winemaking, fermentation generally takes place in temperature-controlled stainless-steel tanks or in barrels. Stainless fermentation is easier to manage with predictable results. Wines fermented in stainless steel also show bright, pure varietal aromas and flavors. Barrel fermentation is used for certain grapes such as Chardonnay to add certain aromatics and flavors, as well as a richer texture. Recently, other fermentation vessels such as concrete eggs have come into common use. The egg shape allows a continuous flow to the wine as it ferments and ages. Also, the thick walls of concrete eggs provide excellent insulation and temperature stability, making refrigeration unnecessary.

Lees Contact

Less are yeasts left from fermentation. Winemakers may choose to leave them in contact with the wine after fermentation to add certain aromas, flavors, and texture. Further, the winemaker may choose to stir the lees in the wine while in barrel to increase the above aromas, flavors, and add to the texture. This practice is called bâtonnage

Malolactic Fermentation (ML)

Though called fermentation, ML is actually a bacterial process where malic acid in the wine is partially converted into lactic acid, reducing the overall acidity as well as giving the wine a softer palate. ML also creates a compound called diacetyl which gives wines such as Chardonnay a buttery, creamy smell and taste. Wines are racked into another tank or barrel to go through ML or afterwards. 

Racking

After the wine has completed fermentation and/or ML, the winemaker may choose to move it into another tank or barrel to avoid lees contact as described above. 

Barrel Aging

White wines such as Chardonnay are commonly aged in barrel from several months to a year. Barrel-aging adds a richer texture, as well as aromas and flavors of toast, vanilla, and spices. 

Cooperage Choice

The size, type, and age of the barrel all play a role in the intensity or presence of oak influence on a wine. Smaller barrels, called barriques, and newer barrels add more influence, while larger and older barrels less. The impact of oak aging in wine is also determined by the degree of toast levels in the barrels, ranging from untoasted, water-treated barrels that add no influence to heavily toasted barrels that add a great deal of oak notes to a finished wine. Finally, the source of the cooperage also will create different aromas and flavors. American oak is known for adding overt vanilla, spice, and dill notes, while French oak is less spicy. 

Topping Off

During barrel aging the fill level of wine in casks must be monitored and wine topped off if necessary. Otherwise, oxidation and issues with bacteria and volatile acidity can take place. 

Cold Stabilization

White wines are commonly cold-stabilized before bottling to remove excess tartaric acid. Cold stabilization involves chilling the wine to 32°F (0°C) for a period of 12-36 hours to allow tartaric acid crystals to form. The wine is then racked off and then bottled. 

Fining

Before bottling, white wines are commonly clarified by fining and filtering. Fining is best described as clarifying a wine by adding a substance to the wine to remove solids left over from fermentation. The most common fining agent is egg whites. Other fining agents include isinglass (a protein substance derived from fish), casein (a protein substance), gelatin, and bentonite (a fine white clay).  After, fining agents are removed from the wine through filtration. 

Filtration

One of the final steps in white winemaking before bottling is filtration. Here the young wine is put through a filtration process using one of a number of different methods. Filtering a wine removes yet more solids and particulate matter in the wine, as well as microbes and yeasts. The degree of filtration for wine available to the winemaker ranges from light polish filtration, where little is removed from the wine, to extreme filtration such as cross-flow filtration and reverse osmosis. The latter two are used to remove alcohol or water from the wine. 

It is important to note that fining and filtration are winemaking choices. Some winemakers choose not to put their wines through either, as they feel both strip wine of volatile compounds that make up aromatics and flavors. 

Blending

If a finished white wine is to be a blend of different grape varieties that have been fermented separately, blending usually occurs after fining and filtration. Likewise, several lots of the same grape variety that have been fermented separately may be blended before finishing the wine. 

Bottling

The final step in the winemaking process is bottling. Wine held in tanks or barrels is then transferred to bottles via an automated bottling line. The empty bottles are first sparged with argon or other inert gas to remove oxygen and dirt, then filled to the appropriate level with the wine. Finally, a closure, either a natural cork, plastic cork, screwcap, or other, is applied to the bottle, along with a small amount of sulfur dioxide which acts as an antioxidant.  

Bottle Age

After bottling the winemaker may choose to allow the newly bottled wines to rest for weeks to several months before release.

Red Winemaking

*Insert diagram of the red winemaking process

Harvest

As with white wine, the timing of harvest is key for producing red wine. The ripeness of the fruit at harvest will determine the alcohol level and style of the finished wine. For example, ripe grapes have higher sugar, which will result in a richer style of wine with higher alcohol. The opposite is also true, with less ripe grapes typically resulting in a lighter wine. Harvesting is done by hand or machine, requiring one or several trips through the vineyard, called “tries” (a French word, pronounced “treez”). In vineyards planted to multiple grapes, several passes through the vineyard will be needed. 

Sorting

Once at the winery, the fruit is sorted by hand or by machines such as optical sorters. Sorting removes damaged grapes or MOG (material other than grapes). 

Fruit Treatment

After sorting there are a number of options open to the winemaker in terms of preparing the fruit for fermentation. Grapes may be crushed and destemmed, destemmed and not crushed, or kept in whole clusters. These choices are determined by the style of wine desired by the winemaker. Whole clusters emphasize fruit qualities and color in a wine, while the addition of stems lends tannin and structure. A winemaker may choose to use partial whole clusters as well. 

Carbonic Maceration 

It is a specific red winemaking technique used to produce fruitier, even “nouveau-style'' red wines intended for near-term consumption. With carbonic maceration, whole bunches of grapes with stems are placed into a stainless-steel tank filled with carbon dioxide. The tank is then sealed. In a short time, intracellular fermentation within the grapes starts creating alcohol and CO2. The process takes between five and 15 days. After, the wine is then racked off the skins which are pressed. The result is a wine with considerable color and fruit, but little tannin. Wines made with carbonic maceration are often described as candied or confected in style. The most well-known example is Beaujolais Nouveau.  In California, nouveau-style wines are also made using this technique. Finally, some winemakers choose to put part of a fermentation through carbonic maceration resulting in a wine that combines structure with youthful, forward fruit. 

Fermentation Vessels

After crushing and destemming (or not), the must is racked into the fermentation vessel. Temperature-controlled stainless-steel tanks are commonly used for red wine fermentation. A variation on standard stainless-steel tanks is the rotary fermenter, a horizontal automated fermentation tank. As the wine ferments, the tank slowly rotates, keeping the must in contact with the pomace (skins and seeds), thereby extracting fruit and color, but less tannin. 

Beyond stainless-steel tanks, there are several other fermentation vessel options for winemakers. Small oak barrels called barriques are sometimes used, as well as large, inert oak casks. Concrete tanks are a traditional fermentation vessel long used in commercial production. As with white wine fermentation, concrete eggs have come into use. The egg shape allows for a continuous flow to the wine as it ferments and ages. The thick walls of concrete eggs provide also excellent insulation and temperature stability, making refrigeration unnecessary.

Pre-fermentation Treatment

Before fermentation the winemaker may choose to keep the must in contact with the skins for a number of days at a cooler temperature. This pre-fermentation maceration, or “cold soak,” as it is often called, extracts fruit and tannin from the skins. SO2 is added at this point, both as a preservative and to prevent fermentation from starting.   

Nutrient Addition

During a cold soak, nutrients including amino acids and nitrogen, may be added to the must to promote an even fermentation. 

Yeast Addition

After a cold soak, yeast is added to the must. Cultured yeasts are commonly used and the choice of yeast is determined by the kind of grape and desired style of wine. Indigenous, or native yeasts, are also used in fermentation. 

Fermentation

Red wine fermentation typically lasts between five and 15 days. Fermentation temperatures for red wine are also considerably higher than those for white winemaking. Average temperatures for red winemaking are in the 80°F (26.7°C) range and even top out at over 90°F (32.2°C). White winemaking, by contrast, is usually in the 60’s (15.5°C). 

Cap Management

During fermentation the hard cap of skins and stems needs to be periodically submerged under the must. This is accomplished by physically punching the cap down by hand. The goal is to ensure that color, fruit, and tannin are extracted from the skins. The must can also be pumped over the cap, sometimes called “autovinification.” Finally, a third cap management technique is called delastage, where a tank of fermenting must is racked out of a tank and pumped back in over the pomace (skins and seeds) to help extract color and flavor compounds. 

Malolactic Fermentation (ML)

After primary fermentation red wines are usually put through ML. The process either starts naturally, due to the malolactic bacteria present in the young wine or winery environment, or by the addition of an ML culture. Unlike white wines, where ML is used to reduce overall acidity and add certain flavors, putting red wines through ML helps stabilize color and the levels of tartaric acid and tannins. 

Post-fermentation

After fermentation and ML the young wine may be kept on the skins for an extended period. Traditionally, Bordeaux grapes such as Cabernet Sauvignon were kept on the skins for up to a month after fermentation. Regardless of duration, post-fermentation skin contact, or maceration, is done to stabilize the color of the wine, as well as to further extract volatile compounds that contribute to the aromas and flavors of the finished wine. After maceration, the wine is pressed off the skins and racked (transferred) to barrels for aging or into stainless steel to settle before filtering and bottling if the wine is not to be aged. The press wine is more tannic and kept separate. It will be aged separately and a portion could be blended back into the rest of the wine before bottling to add tannin and structure. 

Barrel-aging

Wine racked into barrels of varying size will be aged for any number of months up two years. Aging longer for longer periods of time is uncommon. 

Cooperage Choice

The size, type, and age of the barrel all play a role in the intensity or even presence of oak influence in a wine. Smaller barrels (barriques) and newer barrels add more influence, while larger and older barrels less. The impact of oak aging in wine is again determined by the degree of toast levels in the barrels, ranging from light to heavy toast. The winemaker is mindful of matching the toast level to the appropriate grape variety in regards to intensity of aromas and flavors and tannin levels. Cooperage from various locations will create different aromas and flavors. American oak is known for adding overt vanilla, spice, and dill notes, while French oak is less spicy. 

Oak Alternatives and Unoaked Wines

Wines not racked into barrels will be transferred to stainless steel, concrete, or other non-wood containers for a short time before fining, filtering, and bottling. 

Topping off

During barrel-aging the fill level of wine in casks must be monitored and the wine topped off if necessary. Otherwise, oxidation and issues with bacteria and volatile acidity can take place. 

Fining

Like white wines, red wines are commonly clarified by fining and filtering before bottling. Common fining agents are egg whites, isinglass, casein, gelatin, and bentonite. 

Filtration

After fining, the red young wine is filtered to remove solids as well as microbes and yeasts. The degree of filtration ranges from light polish filtration, where little is removed from the wine, to extreme filtration, such as cross-flow filtration and reverse osmosis. The latter two are used to remove alcohol or water from the wine. 

Once again, it is important to note that fining and filtration are winemaking choices. Some winemakers choose not to put their wines through either process, as they feel both strip wine of volatile compounds that make up aromatics and flavors. 

Heat Stabilization

In red wines, tannin can bind to protein causing the wine to become hazy. Heating the wine quickly for a very short duration of time precipitates excess proteins out of the wine which is then bottled.  

Blending

If a finished red wine consists of a blend of different grape varieties that have been fermented separately, blending usually occurs after fining and filtration. Also, several lots of the same grape variety that have been fermented separately may be blended at this time. 

Bottling

The final step in the winemaking process is bottling. Wine held in tanks or barrels is then transferred to bottles via an automated bottling line. The empty bottles are first sparged with argon or other inert gas to remove oxygen, then filled to the appropriate level with wine. Finally, a closure—a natural cork, plastic cork, screwcap, or other—is applied to the bottle, along with a trace of sulfur dioxide, which acts as an antioxidant. 

Bottle Age

After bottling the winemaker may choose to allow the newly bottled wines to rest for several weeks, months, or even years before release. 

Non-bottle Packaging

Some wines are packaged in boxes lined with plastic or polyurethane sleeves, or cans or tetrapaks.

Rosé and Blush Winemaking

*Insert diagram for making rosé wines

Blush wine is known by several different names including vin gris (grey wine), rosé, and white Zinfandel. Regardless of name, the winemaking process is similar to the white and red winemaking methods  described above. However, there are two primary ways to make blush wines and both make use of red grapes: 

  • Leaving the juice on the skins long enough to extract a little color and racking the juice off the skins to complete fermentation. 
  • A method called “saignée,” or to bleed off, where a certain percentage of a red wine must is racked out of the fermentation vessel and then allowed to complete fermentation separately. The saignée technique concentrates the remaining must in the red wine fermentation and also makes a delicious dry rosé. 

Both styles of wine are usually fermented to dryness then fined, filtered, cold-stabilized, and bottled quickly for freshness. However, some traditional styles of European rosé are aged briefly in used cooperage before being bottled.

Sparkling Winemaking

The best sparkling wines are made from blends of different grapes, notably Chardonnay, Pinot noir, and Pinot Meunier (the classic trio used to produce French Champagne). Other secondary grapes include Pinot blanc, Pinot gris, Chenin blanc, Riesling, and Muscat.

Harvest of sparkling winegrapes takes place early in the season because the base wines used for secondary fermentation have to be neutral in character with high acidity. Once in the winery, the grapes are pressed quickly to avoid oxidation, using either a Coquard press typically used in Champagne or a membrane press. 

There are four primary methods of sparkling wine production:

  • Classic Method
  • Transfer Method
  • Charmat Method
  • Carbonation

Classic Method

The classic method involves two separate fermentations. It’s known as Méthode Champenoise when specifically applied to the wines from the Champagne region of France. In other contexts, this method is also known as Méthode Traditionelle. The classic method will be covered in detail, as it represents all quality sparkling wines produced in California. 

Primary fermentation: After pressing and clarification, the juice is placed in temperature-controlled stainless-steel tanks for primary fermentation. Cultured yeast is added and the must fermented at a lower temperature (50-60°F/10-15.5°C). Also, various lots of grapes are fermented separately and later blended for the cuvée. After primary fermentation some wines are allowed to undergo a malolactic fermentation via the addition of ML culture. Most classic method sparkling wines, however, are not put through ML because the process lowers the overall acidity level of the wine, as well as adding flavors such as diacetyl. 

Assembling the cuvée: After primary fermentation, the neutral base wines are blended. In high-quality sparkling wines dozens of different base wines are combined to form the blend, called the “cuvée.” 

Adding the liqueur de tirage: The cuvée is then transferred into bottles, along with a mixture of yeast and sugar called the liqueur de tirage, which leads to a secondary fermentation. The bottles are sealed with a crown cap. 

Secondary fermentation: The bottled cuvée will now undergo a secondary fermentation during the next 6-8 weeks or more, creating CO2 and bubbles. 

Aging en tirage: Once the secondary fermentation is complete the wine is allowed to stay in contact with lees for a period of time ranging from months to several years. During this time there is a gradual breakdown of the yeast cells called “autolysis,” where enzymes are released preventing oxidation. Acetals and amino acids are also developed, giving the wine its toasty character. 

Riddling and use of gyropalette: During tirage, the bottles must be progressively positioned upright so that the spent lees settle in the neck of the bottle to facilitate removal. This is traditionally conducted via a process called riddling, or remuage. In bygone days, riddling by hand was the standard practice. Today it is considered labor-intensive, time consuming, and reserved only for top sparkling wines. Common practice now is to use large machines called gyropalettes, which hold hundreds of bottles and accomplish the same purpose in a fraction of the time. 

Disgorging: After riddling the bottles are now upside down with the spent yeasts in the neck. The bottles are then placed in a freezing brine solution, uprighted, and the crown caps popped. The pressure inside the bottles expels the semi-frozen yeast. 

Dosage: A mixture of wine and sugar is added, adjusting the sweetness level of the wine. It’s important to note that until the dosage is added, all classic method sparkling wines are bone dry. The actual style of the wine decided by the amount of sweetness in the dosage is determined at the end of the winemaking process. 

Finishing: After the dosage is added the bottles are quickly sealed with a cork and a cage placed over the top. The capsule and labels may be added at this time or after aging. 

Aging: The bottles are aged for a specified period of time ranging from 18 months to five years, depending on the specific kind of wine. 

Styles: There are several styles of classic method sparkling wine.  

  • Non-vintage/multi-vintage: A wine produced from base wines taken from several different vintages. 
  • Vintage: A wine that is the product of a single harvest/vintage. 
  • Rosé: Blush/pink sparkling wine made with one of two methods: Skin contact during red grape fermentation affecting the color. Also, by blending a small percentage of red wine into the base cuvée before secondary fermentation.  
  • Blanc de Blancs: Made entirely from Chardonnay or other white grapes. 
  • Blanc de Noirs: Made entirely from red grapes, such as Pinot noir and Pinot Meunier. 
  • Prestige Cuvée: A term usually reserved for top Champagnes. Some of the best California sparkling wines, however,  are also referred to as prestige cuvées.

Other Sparkling Wine Methods

Transfer Method

The process for the Transfer Method is similar to the classic method. The primary fermentation is conducted in stainless steel tanks and then the cuvée is assembled. The secondary fermentation takes place in the bottle. However, during disgorgement the bottles are emptied under pressure into a large tank. The wine is then filtered under pressure and rebottled. The advantages of the Transfer Method are that the wine undergoes lees contact but doesn’t have to be riddled. The Transfer Method is used for large-format bottles, as well as the small 187ml bottles used on airlines. 

Charmat Method (“Cuve Close”)

In the Charmat Method the secondary fermentation takes place in pressurized tanks and is complete within 4-5 days. The wine is then filtered and bottled. The Charmat Method takes less time, is less costly, and no riddling or disgorging is needed. The method is commonly used for mass-market sparkling wines. It’s also the best method for aromatic grapes such as Muscat. 

Carbonation

The carbonation method of producing sparkling is as the name implies: Adding CO2 to still wine before bottling. The bottles must be labeled as carbonated wine and are usually sweet in style.