Weekend Wine Word – Wine Press

A wine press is a device used to extract juice from crushed grapes during wine making. There are a number of different styles of presses that are used by wine makers but their overall functionality is the same. Each style of press exerts controlled pressure in order to free the juice from the grapes. The pressure must be controlled, especially with grapes, in order to avoid crushing the seeds and releasing a great deal of undesirable tannins into the wine.

Types of Presses

A basket press consists of a large basket that is filled with the crushed grapes. Pressure is applied through a plate that is forced down onto the fruit. The mechanism to lower the plate is often either a screw or a hydraulic device. The juice flows through openings in the basket. The basket style press was the first type of mechanized press to be developed, and its basic design has not changed in nearly 1000 years.

A horizontal screw press works using the same principle as the basket press. Instead of a plate being brought down to put pressure on the grapes, plates from either side of a closed cylinder are brought together to squeeze the grapes. Generally the volume of grapes handled is significantly greater than that of a basket press.

A bladder press consists of a large cylinder, closed at each end, into which the fruit is loaded. To press the grapes, a large bladder expands and pushes the grapes against the sides. The juice then flows out through small openings in the cylinder. The cylinder rotates during the process to help homogenize the pressure that is placed on the grapes.

A continuous screw press differs from the above presses in that it does not process a single batch of grapes at a time. Instead it uses an Archimedes screw to continuously force grapes up against the wall of the device. Juice is extracted, and the pomace continues through to the end where is it extracted. This style of press is not often used to produce table wines, and some countries forbid their use in higher quality wines.

Weekend Wine Word – Barrel

Oak is used when making wine barrels. The use of oak in wine plays a significant role in winemaking and can have a profound effect on the resulting wine, impacting the color, flavor, tannin profile and texture of the wine. Oak usually comes in contact with wine in the form of a barrel during the fermentation or aging periods. It can be introduced to the wine in the form of free floating oak chips or as wood staves (or sticks) added to wine in a fermentation vessel like stainless steel. Oak introduced in the form of a wine barrel can impart other qualities to the wine through the process of evaporation and low-level exposure to oxygen.

How an oak wine barrel is made.

Weekend Wine Word – Wine Cellar

A wine cellar is a storage room for wine in bottles or barrels, or more rarely in carboys, amphorae or plastic containers. In an active wine cellar, important factors such as temperature and humidity are maintained by a climate control system. In contrast, passive wine cellars are not climate-controlled, and are usually built underground to reduce temperature swings. An aboveground wine cellar is often called a wine room, while a small wine cellar (less than 500 bottles) is sometimes termed a wine closet.

As you can see from the picture above – wine cellars can be quite stunning looking the attention to detail is amazing. This particular wine cellar is located at Devil’s Thumb Ranch.

Learn more about them here and here.

Weekend Wine Word – Reverse Osmosis

Reverse osmosis is a more economical operation for concentrating food liquids (such as fruit juices) than conventional heat-treatment processes. Research has been done on concentration of orange juice and tomato juice. Its advantages include a low operating cost and the ability to avoid heat treatment processes, which makes it suitable for heat-sensitive substances like the protein and enzymes found in most food products.

Reverse osmosis is extensively used in the dairy industry for the production of whey protein powders and for the concentration of milk to reduce shipping costs. In whey applications, the whey (liquid remaining after cheese manufacture) is pre-concentrated with RO from 6% total solids to 10-20% total solids before UF (ultrafiltration) processing. The UF retentate can then be used to make various whey powders including WPI (whey protein isolate) used in bodybuilding formulations. Additionally, the UF permeate, which contains lactose, is concentrated by RO from 5% total solids to 18–22% total solids to reduce crystallization and drying costs of the lactose powder.

Although use of the process was once frowned upon in the wine industry, it is now widely understood and used. An estimated 60 reverse osmosis machines were in use in Bordeaux, France in 2002. Known users include many of the elite classed growths (Kramer) such as Château Léoville-Las Cases in Bordeaux.

Reverse osmosis is used globally throughout the wine industry for many practices including wine and juice concentration, taint removal; such as acetic acid, smoke taint and brettanomyces taint; and alcohol removal. The patent holder for these processes, Vinovation, Inc., claims to have served over 1000 wineries worldwide, either directly or through one if its licensed partners, in the last 15 years. Its use has become so widely accepted that patent infringers have sprung up on several continents.

Learn more about it here and here.

Weekend Wine Word – Phylloxera

Phylloxera, is a pest of commercial grapevines worldwide, originally native to eastern North America. These tiny, pale yellow sap-sucking insects, related to aphids, feed on the roots of grapevines. In Vitis vinifera, the resulting deformations (“nodosities” and “tuberosities”) and secondary fungal infections can girdle roots, gradually cutting off the flow of nutrients and water to the vine. Nymphs also form protective galls on the undersides of grapevine leaves and overwinter under the bark or on the vine roots; these leaf galls are not found on vines grown in California.

The majority of grape phylloxera adults are wingless females. They are generally oval shaped, but those that lay eggs are pear shaped. They are small (0.04 inch long and 0.02 inch wide) and vary in color from yellow, yellowish green, olive green, to light brown, brown, or orange. Newly deposited eggs are yellow, oval, and about twice as long as wide. Nymphs resemble adults except they are smaller.

Grape phylloxera overwinter as small nymphs on roots. In spring when soil temperatures exceed 60°F, they start feeding and growing. First instar nymphs are active crawlers and may move from plant to plant in the ground, on the soil surface, or by blowing in the wind. They may also be moved between vineyards on cuttings, boots, or equipment. Established phylloxera feed externally in groups on roots. In fall when soil temperatures fall below 60°F, all life stages die except the small nymphs. There are three to five generations each year.

Learn more about them here and here.

Weekend Wine Word – Acidity

The quality of wine that gives it its crispiness and vitality. A proper balance of acidity must be struck with the other elements of a wine, or else the wine may be said to be too sharp – having disproportionately high levels of acidity – or too flat – having disproportionately low levels of acidity. The three main acids found in wine are tartaric acid, malic acid and lactic acid. The first two come from the grapes and the third from Malolactic fermentation which often occurs in the winemaking process.

tataric acid structure

Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds," the small potassium bitartrate crystals that sometimes form spontaneously on the cork. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization. The tartrates that remain on the inside of aging barrels were at one time a major industrial source of potassium bitartrate.

However, tartaric acid plays an important role chemically, lowering the pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation. In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role.

malic acid structure

Malic acid is present in grapes. It confers a tart taste to wine, although the amount decreases with increasing fruit ripeness. The process of malolactic fermentation converts malic acid to much milder lactic acid.

Malolactic fermentation tends to create a rounder, fuller mouthfeel. It has been said that malic acid tastes of green apples – indeed, malic comes from the Latin word for apple, mālum, and is present in apple juice – and this can be tasted in the wine.

lactic acid structure

By contrast, lactic acid is richer, even unctuous, and more buttery tasting – corresponding to its presence in milk, as reflected in the word lactic being derived from the Latin word for milk, lac, and it is present in sour milk.

Information found on Wikipedia.

Weekend Wine Word – Pinot Noir

Pinot noir – pronounced ‘pi-no-nwar’ is a red wine grape variety. Also refering to wines produced predominantly from pinot noir grapes.

The leaves of Pinot noir are usually smaller than those of Cabernet Sauvignon, although larger than those of Syrah. The name is derived from the French words for "pine" and "black" alluding to the varietals’ tightly clustered dark purple pine cone shaped bunches of fruit. Pinot noir tends to produce narrow trunks and branches. In the vineyard it is sensitive to light exposure, soil types, pruning techniques and yield levels. Its thin skin makes it highly vulnerable to bunch rot and other diseases. The vines themselves are prone to downy mildew, leaf roll, and fanleaf. These complications have given the grape the reputation of being difficult to grow. In the winery it is sensitive to fermentation methods and yeast strains.

"minx of a vine" – Jancis Robinson

"God made cabernet sauvignon whereas the devil made pinot noir." – André Tchelistcheff

Pinot noir is a primeval variety that may be only 1-2 generations removed from naturally wild vines. The origins of the variety are unclear: In De re rustica, Columella describes a grape variety similar to Pinot Noir in Burgundy during the 1st century A.D., however, vines have grown wild as far north as Belgium in the days before phylloxera, and it is possible that Pinot represents a self-sufficient domestication of Vitis vinifera.

Pinot noir grapes are grown around the world, mostly in the cooler regions, but the grape is chiefly associated with the Burgundy region of France. It is commonly considered to bring into being some of the finest wines in the world, and as we have learned is a highly complex variety to cultivate and transform into wine.

Weekend Wine Word – Brix

Brix (symbol °Bx) is a measurement scale of the mass ratio of dissolved sucrose to water in a liquid. Because Brix is related to the concentration of dissolved solids in a solution (primarily sucrose), as a result it is related to the specific gravity of the liquid. Because the specific gravity of sucrose solutions is well known, it can also be measured by refractometers (most are calibrated for Sucrose).

Modern Brix meters are digital refractometers that discover that “magical” Brix value, based on refractive index. These meters are usually portable and extremely simple to use. More and more often, Brix is measured to determine ideal harvesting times of fruit and vegetables. This ensures that the product arrives to the consumers in a perfect state, or are ideal for subsequent processing steps, such as wine making.

Each degree Brix is equivalent to 1 gram of sugar per 100 grams of grape juice. In regards to wine production, a reading of 20 to 25 deg. Brix is the most favorable degree of grape ripeness at harvest, as it pertains to the majority of table wines. For example, a 25 °Bx solution is 25% (w/w), with 25 grams of sucrose sugar per 100 grams of liquid. Or, to put it another way, there are 25 grams of sucrose sugar and 75 grams of water in the 100 grams of solution. As a good rule of thumb, about 55 to 60% of the sugar is converted into alcohol. See below for some conversion formulas to help you determine your wine’s alcohol content and specific gravity.

The estimated alcohol that a wine will produce is called Potential Alcohol and is calculated using the following formula:

°Bx Reading x 0.55 = PA of Finished Wine
Or use the form below to perform this calculation right here.

For individuals requiring Specific Gravity units of measurement, use the following formula:

°Bx Reading x 0.00425 + 0.9988 = SG of Sucrose @ 20°C (68°F
)
Or use the form below to perform this calculation right here.

Specific Gravity Ranges:

• 1.085 – 1.100 – Dry Wine
• 1.120 – 1.140 – Medium Sweet Wine
• 1.140 – 1.160 – Sweet Wine

Have a great weekend. Be safe, and please, always have a designated driver when you are drinking. More to come next week!