Wine

wine-grapes
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Key Factswiki_pending

• Wine is the preferred alcoholic beverage of 35% of American adults and contributed a record $34.6 billion in sales to the U.S. economy in 2012.,
• Wine has religious significance, often symbolizing blood or sacrifice. It is commonly used in religious ceremonies, toasts and while cooking.
• Wine is produced in all 50 U.S. States in the amount of 18.5 million hectoliters annually. The U.S. is the fourth largest country in wine production following France, Italy, and Spain.
• Historically, there have not been any foodborne pathogens associated with finished wine products. The 1985 adulteration of 36 million bottles of Austrian wine with diethylene glycol, the toxic compound in antifreeze responsible for its sweet flavor, is the most significant food safety issued associated with wine to date.

Introduction

There are many different types of wine, which are categorized by color, taste, and grape variety. Wine is often paired with certain meals or foods based on its taste and characteristics. Wine is produced from fruits other than grapes, including apples, raspberries, and strawberries. In addition to red and white, fruit wines and sparkling wines, such as champagne, are the most common types of wine.

Most wines are made from grape varieties belonging to the species Vitis vinifera, due to the high sugar content that is ideal for the fermentation process. The most common wine grape varieties in the U.S. are Cabernet Sauvignon, Chardonnay, Pinot Noir, Merlot, and Zinfandel.

While all 50 U.S. states produce wine, 95% of wine is produced in California, Washington, Oregon, and New York, with the majority of production occurring in California, specifically the Napa Valley region.

The per capita consumption of wine in the U.S. is 2.73 gallons/year.

Regional Information

There are around 100 wineries in Colorado, many of which are situated near the state’s border with Utah. The high altitude of Colorado’s wineries provides ideal conditions for viticulture due to the moderate climate and rocky, sandy soil. The most common wine grape varieties grown in Colorado are Merlot, Cabernet Sauvignon, Riesling, and Chardonnay.

Foodborne Outbreaks

To contribute to the Wine Foodborne Outbreaks section, please follow this link: http://fsi.colostate.edu/suggest-a-topic/

Production

Grape Growing and Harvesting

Enology and viticulture are the sciences of wine making and wine-grape growing, respectively.

Successfully growing wine grapes depends on a delicate balance of sunlight and climate and soil conditions. Vines grow best in sandy soils because they drain easily, maintain nutritious organic material, and have a pH within the ideal range of 5.5 to 7.0. Soil pH can be increased with lime or decreased with sulfur.

Mycorrhizal fungi are soil microbes with which grape vines develop a symbiotic exchange of nutrients necessary for optimal growth. Planting a cover crop can help encourage the growth of mycorrhizae.

Grapes are harvested when ripe, which is determined by several factors, including taste. Harvesting can be done mechanically or by hand, but many producers prefer to harvest grapes by hand to prevent damage to the grapes and the vineyard. Once grapes have been harvested, they are transported to the winery where the winemaking process begins.

Processing of Wine Grapes

One of the early steps in the winemaking process is sulfating, which involves treating grapes with sulfur dioxide in order to remove unwanted microorganisms, including yeast from the grapes. While yeast is necessary for fermentation to occur, most producers remove wild yeast strains from the grapes and later add a specific strain of yeast for better predictability and uniformity throughout the winemaking process. Inadequate treatment with sulfur dioxide can lead to decay of stored grapes.

Crushing and Pressing

Grapes used to make white wine are transferred to a machine called a winepress where the grapes are squeezed to separate the juice from the skins, seeds, and other solids. This prevents unwanted color and tannins from leaching into the wine. In red wine production, the skins, pulp, and seeds of the grapes are used for added color, flavor, and tannins. A machine called a crusher-destemmer gently crushes the grapes producing must. The must is then allowed to cold soak for a few days and may be further treated with sulfur dioxide to remove bacteria and yeast. The cold soak process allows the juice to gain color and flavor.

Fermentation

The grape juice is transferred to fermentation vats and yeast is added. The species of yeast used in the winemaking process is Saccharomyces cerevisiae. Fermentation is the process of turning sugar and yeast into ethanol (alcohol) and carbon dioxide. It takes about 10 to 30 days for all of the sugar to be converted into alcohol, producing a dry wine. Some producers will intentionally halt fermentation before it is finished to produce a sweeter wine. The alcohol content is dependent on the amount of sugar in the must. In cool climates, an alcohol level of 10% is considered normal, versus 15% in warmer climates.

Clarification

The clarification process takes place once fermentation is completed to remove solids and precipitates, called pomace, from the wine. This can be accomplished by siphoning wine from one barrel to another, by filtration, or by fining. Fining is the addition of substances, such as egg whites or clay, which will precipitate dead yeast cells and solids out of the wine. The substances will sink to the bottom of the barrel and the clarified wine will be siphoned into another barrel.

Aging and Bottling

After clarification, the wine can be bottled immediately or further aged. The aging process is defined as the time between the end of fermentation and consumption of the wine and can last for varying periods of time depending on the type. In general, red wines are aged longer than white wines. Aging in oak or redwood barrels can add flavor to the wine, but aging can also be done in bottles or steel tanks.,

Storage of Wine

There are four main things to remember when it comes to storing wine: keep it cool, keep it dark, keep it sideways, and keep it still. Storing wine around 55°F and 65-75% humidity will prevent the corks from shrinking, which will allow oxygen to enter the bottle and result in oxidation of the wine. Exposure to light will cause premature aging, especially in white wines. Keeping wine in places where it is constantly being moved will prevent sediment from settling and ruin the wine; even the vibrations of the refrigerator can negatively affect wine. Storing bottles sideways will keep the cork moist by keeping it in contact with the wine; this will also prevent oxidation and spoiling of the wine.

Food Safety

Arsenic

Wine, particularly white wine, may contain arsenic, a naturally occurring toxic compound in water and soil. It may be added to the wine during the filtration process, although the exact mechanism of how arsenic ends up in wine is unknown. It is likely a result of untested water, such as well water, being used in the winemaking process. However, wine may also inhibit the body’s ability to detoxify arsenic.

Tannins and Histamines

Histamines are naturally occurring compounds found in many foods, including wine. Both histamines and tannins may elicit an allergic response in sensitive individuals. Red wine has higher levels of histamines and tannins than white wine, due to the inclusion of grape skins in the winemaking process. Dizziness or flushed skin may be a sign that a person is having a reaction to histamines. Histamines are also known to worsen asthma and eczema.

Sulfites

Sulfites are the ingredient in wine, particularly white wine, which causes headaches in certain individuals. Headaches may also be caused by the alcohol, which dilates blood vessels. Even sulfite-free wines have some sulfites because yeast fermentation produces 5-20 ppm and sulfites also naturally occur in grapes—nature’s way of preventing microbial growth. Sulfites are also added to wine to prevent it from turning into vinegar.

The maximum allowable total sulfite level in wine is 300 ppm, most wine is usually below 150 ppm but sulfite sensitivity for some individuals can begin as low as 10 ppm.

Pesticide Residues

Pesticides, herbicides, and fungicides are often applied to grapevines in order to yield a high-quality product. The concentration of these chemicals is greatly reduced over time and following the fermentation process, but high levels can still remain in the finished wine product. As a result, maximum residue levels have been set to protect consumers.

Grape Leaves

The leaves of grape vines, which are a rich source of Vitamin A, are often used in Mediterranean cuisine. Leaves should come from vines that have not been sprayed with pesticides and they should be rinsed well. Traditional cooking methods call for the leaves to be blanched before use. Some older recipes for homemade pickles call for adding a grape leaf to each jar to inhibit enzymatic processes and help maintain crispness, however, removing the blossom ends (the source of undesirable enzymes) make the addition of grape leaves unnecessary.

Consumption

To contribute to the Wine Consumption section, please follow this link: http://fsi.colostate.edu/suggest-a-topic/

Nutrition and Health

While excessive consumption of any alcoholic beverage, including wine, has been shown to have detrimental health effects, multiple studies have shown moderate wine consumption to be protective against certain diseases. Moderate wine consumption is defined by the Dietary Guidelines as one drink per day for women and two drinks per day for men. However, it is not recommended to increase drinking to these levels every day of the week; these guidelines are intended for a single day. Consuming more than 8 drinks per week for women, 15 for men, is considered heavy drinking and is associated with increased morbidity and mortality.

Evidence from epidemiological studies indicates that there is an inverse association between moderate wine consumption and cardiovascular disease risk, hypertension and certain cancers and neurologic disorders. This is especially true of red wine due to the higher levels of polyphenols. Polyphenols have been shown to have neuroprotective effects due to their antioxidant properties.

References

Author

Natalie Tsevdos

Natalie Tsevdos

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