WINE

WINE

Wine is an alcoholic beverage made from fermented fruit juice, usually that of grapes. Wines made from other fruits are usually named after the fruit from which they are produced (for example, apple wine or elderberry wine) and are generically called fruit wine.
The term “wine” can also refer to the higher alcohol content of starch-fermented or fortified beverages such as barley wine, sake, and ginger wine.

Classification of wine

The classification of wine can be done according to various methods including, but not limited to, place of origin or appellation, vinification methods and style, colour, body of wine, sweetness and vintage, or grape variety used. Practices vary in different countries and regions of origin, and many practices have varied over time. Some classifications enjoy official protection by being part of the wine law in their country of origin, while other have been created by, for example, grower’s organizations without such protection.
Regulations govern the classification and sale of wine in many regions of the world. European wines tend to be classified by region (e.g. Bordeaux and Chianti), while non-European wines are most often classified by grape varietals (e.g.Pinot noir and Merlot). More and more, however, market recognition of particular regions is leading to their increased prominence on non-European wine labels. Examples of recognized locales include: Napa Valley in California, Barossa Valley in Australia, Willamette valley in Oregon, Marlborough in New Zealand, and Douro in Portugal.

Classification of wines

By appellation (generic styles true to tradition of region of origin)
Historically, wines have been known by names reflecting their origin, and sometimes style: Bordeaux, Rioja , Mosel and Chianti are all legally defined names reflecting the traditional wines produced in the named region. These naming conventions or “appellation” (as they are known in France) dictate not only where the grapes in a wine were grown but also which grapes went into the wine and how they were vinified. The appellation system is strongest in the European Union, but a related system, American Viticultural Area( AVA) restricts the use of certain regional levels in America, such as Napa Valley, Santa Barbara and Willamette valley. (However, the AVA designations do not restrict the type of grape used.)

Europe classification

France has an appellation system based on the concept of terroir, with classifications which range from Vin de Table (“table wine”) at the bottom, through Vin de Pays and Vin Delimite de Qualite Superieure (VDQS) up to Appellation de Origine Controlee (AOC). Portugal has something similar and, in fact, pioneered this technique back in 1756 with a royal charter which created the “Demarcated Douro Region” and regulated wine production and trade. Germany did likewise in 2002, although their system has not yet achieved the authority of those of the other countries’. Spain and Italy have classifications which are based on a dual system of region of origin and quality of product.

Outside of Europe

New World Wine—wines from outside of the traditional wine growing regions of Europe, for e.g. wines from South Africa, California, Australia, New Zealand, Argentina, Chile, India, etc—tend to be classified by grape varietals rather than by terroir or region of origin, although there have been non-official attempts to classify them by quality.
A varietal wine is wine made from a dominant grape such as a Chardonnay or a Cabernet Sauvignon. The wine may not be entirely of that one grape and varietal labeling laws differ. In the United States a wine needs to be composed of at least 75% of a particular grape to be labeled as a varietal wine. In the European Union, a minimum of 85% is required if the name of a single varietal is diplayed, and if two or more varietals are mentioned, these varietals combined must make up 100% and they must be listed in descending order. E.g., a mixture of 70% Chardonnay and 30% Viognier must be called Chardonnay-Viognier rather than Viognier-Chardonnay.
Some blended wine names are marketing terms, and the use of these names is governed by trade mark or copyright law rather than by specific wine laws. For example, Meritage is generally a Bordeaux-style blend of Cabernet Sauvignon and Merlot, and may also include Cabernet Franc, Petit Verdot, and Malbec. Commercial use of the term “Meritage” is allowed only via licensing agreements with a California based organization called the “Meritage Association”, now called the Meritage Alliance

Classification By colour

The color of wine is not determined by the juice of the grape, which is almost always clear, but rather by the presence or absence of the grape skin during fermentation. Red wine is made from red (or black) grapes, but its red color is bestowed by a process called maceration, whereby the skin is left in contact with the juice during fermentation. The skins of these grapes contain the pigment called “anthocyanin” which contributes colour to red and rose wines. White wine can be made from any colour of grape as the skin is separated from the juice during fermentation. A form of rosé is called Blanc de Noirs where the juice of red grapes is allowed contact with the skins for a few hours. Some producers of rosé wine merely blend red and white wines to produce the desired pink hue. However this method is discouraged in most wine regions except for Champagne. The term “blush” is generally restricted to certain rosé wines sold in North America, although it is sometimes used in Australia.

By body

Body is a tasting term describing the weight and fullness of a wine that can be sensed while drinking or tasting. A wine may be light-, medium-, or full-bodied. Wines rich in concentration, extract, alcohol, tannin and glycerol may be described as full-bodied. During a meal a wine may be chosen based on its compatibility with the texture, taste and flavor of the dish. For e.g, a light-bodied wine may complement a delicate texture like white fish while a full-bodied (red) wine would do better justice to the firmness of a steak.

By vinification methods

Table wines may have an alcohol content that is no higher than 14% in the U.S. In Europe, they tend to be within 8.5% and 14% alcohol by volume. As such, unless a wine has more than 14% alcohol, or it is carbonated, it is a table wine. As mentioned earlier, table wines are usually classified as “white,” “red,” or “rosé,” depending on their colour.
However in Europe another interpretation of the term “Table wine” exists. In Europe ‘vins de table’ (in French), ‘vino da tavola’ (in Italian), ‘Tafelwein’ (in German) or ‘vino de mesa’ (in Spanish), which translate to ‘table wine’ in English, are cheaper wines that often do not include the information on the grape variety used or the region of origin on the bottle label.

-Sparkling and still wines

Sparkling wines contain carbon dioxide which is produced naturally from fermentation or force-injected later. To have this effect, the wine is fermented twice, once in an open container to allow the carbon dioxide to escape into the air, and a second time in a sealed container, where the gas is caught and remains in the wine. Sparkling wines that gain their carbonation from the traditional method of bottle fermentation are called ‘Bottle Fermented’, ‘Méthode Traditionelle’, or ‘Méthode Champenoise. The latter designation is considered wrong by those who hold that Champagne refers to the origin as well as the method of production. Other international denominations of sparkling wine include Sekt or Schaumwein (Germany), Cava (Spain), and Spumante (Italy). ‘Semi Sparkling wines’ are Sparkling Wines that contain less than 2.5 atmospheres of carbon dioxide at sea level and 20 °C. Examples of Semi-Sparkling wines are Frizzante in Italy, Vino de Aguja in Spain, and Petillant in France. In most countries except the United States, champagne is legally defined as sparkling wine originating from a region (Champagne, Towns “Reims, Épernay”) in France. Still wines are wines that have not gone through the sparkling wine methods and have no effervescence.

-Dry and Sweet/Dessert wine

The sweetness of wine is determined by the amount of residual sugar in the wine after fermentation, relative to the acidity present in the wine. Depending on how much sugar is retained following fermentation, the result will be a dry, medium dry or a sweet wine. If fermentation leaves behind no residual sugar at all the result is a dry wine. Most red and rose wines tend to dry or medium dry. White wines may have a varied range in sweetness level.
Dessert wines are mostly based on certain white grape varieties. They range from slightly sweet (with less than 50 g/L of sugar) to incredibly sweet wines (with over 400 g/L of sugar). Late harvest wines such as Spätlese are made from grapes harvested well after they have reached maximum ripeness. Dried grape wines, such as Recioto and Vin Santo from Italy as well as Vinsanto from Santorini Greece, are made from grapes that have been partially raisined after harvesting. Botrytized wines are made from grapes infected by the mold Botrytis cinerea or noble rot. These include Sauternes from Bordeaux, numerous wines from Loire such as Bonnezeaux and Quarts de Chaume, Tokaji Aszú from Hungary and Tokaj from Slovakia, and Beerenauslese from Germany and Austria. Eiswein is made from grapes that are harvested while they are frozen, and are commonly from the Niagara and Okanagan regions in Canada, Germany, and Austria.

Fortified wines

Fortified wines are often sweeter, and generally more alcoholic wines that have had their fermentation process stopped by the addition of a spirit, such as brandy, or have had additional spirit added after fermentation. Examples include Port, Madeira and Banyuls. Sherry is an example of a white fortified wine from Spain which is traditionally dry and drunk as an aperitif although sweet Sherries are also made.

Aromatised wines

These proprietary wines are fortified and flavoured with herbs. They are usually drunk by themselves as aperitifs or are incorporated in cocktails. The best known examples are vermouth and Dubonnet.
Vermouth is a fortified wine flavored with aromatic herbs and spices using closely-guarded recipes. Vermouth may be sweet or dry, albeit, with a bitter taste. Cinzano and Martini & Rossi are popular Italian brands while Noilly Prat is French.

Other styles

A vintage wine is one made from grapes that were all, or primarily, grown in a single specified year, and are accordingly dated as such. Consequently, it is not uncommon for wine enthusiasts and traders to save bottles of an especially good vintage wine for future consumption. However, there is some disagreement and research about the significance of vintage year to wine quality. Most countries allow a vintage wine to include a portion of wine that is not from the labeled vintage.
Organic wine is made from grapes that have been grown without the use of chemical fertilizers, pesticides, fungicides and herbicides. Winemaking techniques should be organic as well; little or no manipulation of wines by reverse osmosis, excessive filtration, or flavor additives (such as oak chips). Many organic winemakers also prefer wild yeasts for fermentation.
Biodynamic wines are made using the principles of biodynamic agriculture. In most cases, one speaks of wine made from biodynamic grapes. Increasingly these biodynamic wines are becoming known as BD wines.
The practice of biodynamics in viticulture (grape growing) has become popular in recent years in several growing regions, including France, Switzerland, Italy, Austria, Germany, Australia, Chile, South Africa, Canada, and the United States.
Like biodynamic agriculture in general, biodynamic grape-growing stems from the ideas and suggestions of Rudolf Steiner (1861–1925).

FACTORS AFFECTING THE QUALITY OF WINE

The grape variety used for a wine is the most influential factor in determining it’s taste. The factors that determine the inherent flavour of any grape variety are the same as those that determine the varietal taste of any fruit.

The following factors affect the taste and quality of a wine:
Size of the fruit: The smaller the fruit, the more concentrated the flavour will be. The most classic grape variety such as Cabernet Sauvignon and Riesling , have small berries, although some varieties that rely on elegance than power of concentration such as Pinot noir may yield large berries. Many varieties are known as petit or gros something and it is always petit that is always the better variety. Petit vidure is Cabernet sauvignon and gros vidure is Cabernet franc. Petit rhin is Riesling and gros rhin is
Sylvaber.

Skin structure:

The skin contains most of the aromatic characteristics with which we associate the varietal identity of any fruit. It’s construction and thickness therefore of paramount importance. For example the thick skinned Sauvignon blanc produce an aromatic wine that when ripe varies in pungency from peach in a warm climate to gooseberry in a cool climate and when under ripe through various degree of herbaceousness ranging from grassy to elderflower to even “cat’s pee”. Meanwhile the thin skinned Semillon produces a rather neutral wine although it’s thin skin makes it susceptible to noble rot and is thus capable of producing one of the world’s greatest botrytised sweet wines with mind blowing aromatics.
Skin colour and thickness: A dark coloured thick skinned grape such as Cabernet sauvignon produces very deep coloured wines while the lighter coloured thin skinned grapes such as Merlot produces a less intense wine.

Acid sugar ratio and other constituents:

The grape sugar content dictates the alcohol level and whether any natural sweetness is possible, this together with the acidity level, determines the balance. The proportion of the grape’s other constituents or their products after fermentation form the subtle nuances that differentiate the various varietal characters. Although soil, root stock and climate have their effect on the ultimate flavour of the grape, the basic recipe for these ingredients is dictated by the genetics of the vine.
The vitis family( grape variety) The vine family is a large and diverse family of plants ranging from the tiny pot plant Kangaroo vine to the Virginia creeper. The vines belong to a family called Vitaceae or Ampelidaceae. The family Vitaceae has ten genera and one of the Genus is Vitis which grow grapes suitable for wine making. The genus Vitis has a sub genus called Euvites. The sub genus Euvites has some 60 species and the only the species Vitis vinifera produces grapes suitable for quality wine making. There are some thousand varieties of grapes produced but only a few are actually suitable for wine making. Vifis vintf’era, probably originating in the Caucasus Mountains, is the principal wine- producing plant, with most of the world’s wine still made from varieties of this species. V. labrusca and V. rotundifolia have been domesticated in the eastern United States, the domestication of V. amurensis has been reported in Japan, and various interspecies hybrids have been used for wine production. The high sugar content of most V vinifera varieties at maturity is the major factor in the selection of these varieties for use in much of the worlds Wine production. The moderate acidity of ripe grapes of the V. vinifera varieties is also favourable to wine making; the fruit has an acidity of less than 1 percent (calculated as tartaric acid, the main acid in grapes) and a pH of 3.1 to 3.7 (mildly acid). Malic acid is also an important acid; only small amounts of citric acid are present. A third factor attracting wine makers to this grape is its tremendous range in composition. The pigment pattern of the skin varies from light greenish yellow to russet, to pink, red, reddish violet, or blue-black; the juice is generally colourless, although some varieties have a pink to red colour, and the flavour varies from quite neutral to strongly aromatic (Gewurztraminer, Cabernet Sauvignon, and Zinfandel). Some varieties, such as Pinot Noir, having rather neutral flavoured juice, develop a characteristic flavour when fermented on the skins and aged

Phylloxera Vastatrix – pest or blessing:

The vine louse – phylloxera vastatrix that devastated the vineyards in Europe in the late 19th century still infests the soils of nearly all the world’s wine producing regions. At the timke it considered the greatest disaster in the history of wine but in the hindsight it was a blessing inn disguise.
Before phylloxera arrived, many of Europe’s greatest wine regions had gradually been devalued because of an increase in demand for their wines. This led to bulk producing, inferior varieties being planted and vineyards being extended into unsuitable lands. As the phylloxera spread, it became apparent that every vine had to be grafted onto phylloxera resistant American rootstock. This forced a much needed rationalization in which the best sites in the classic regions were replanted and only noble vines were cultivated, a costly and time consuming operation that owners of the vineyards in lesser areas could not afford. The grafting took France 50 years and enabled the Appellation d’ Origine Controllee system to be established. It is hard ti imagine what regional or varietal identities might now exist if phylloxera had not occurred.

Rootstock:

Hundreds of rootstock varieties have been developed from various vine species, usually berlandieri, riparia or rupestris because they are the most phylloxera resistant. The choice of rootstock depends on it’s suitability to the vine stock on which it is grafted. It is also dependant on the adaptability to the geographical location and soil type but the choice can increase or decrease the vine’s productivity and thus has a strong effect on the quality of the wine. Generally the lower the quantity, higher the quality.

LATITUDE

The vast majority of the world’s wine producing regions are found between the temperate latitudes of 30° and 50° in both hemispheres. Grapes, although primarily a temperate-zone plant, can be grown under semitropical conditions. They are not adapted to the cooler parts of the temperate zone, where growing seasons may be too short to allow the fruit to reach maturity or where low winter temperatures (less than -7° C [20°F]) may kill the vine or its fruitful buds.

LOCATION/TOPOGRAPHY

Other factors that viticulturists consider are the topography of the area with hillsides and slopes being preferred over flatter terrain. A main for this is that vines on an angle can receive a greater strength of the sun rays with the sunshine falling on a perpendicular angle to the slope. With flatter terrain, the strength of the sunlight is diluted as it is spread out across a wider surface area. An additional benefit is the natural drainage that a slope offers so that the vine doesn’t sit with too much moisture in the soil. In cooler climate regions of the northern hemisphere, South facing slopes receive more hours of sunlight and are preferred. In warmer climates, north facing slopes are preferred. (In the southern hemisphere this orientations are reversed).

SOIL

The soil composition of vineyards is one of the most important viticulture considerations when planting grape vines. The soil supports the root structure of the vine and influences the drainage levels and amount of minerals and nutrients that the vine is exposed to. The ideal circumstance for a vine is an area of thin topsoil and subsoil that sufficiently retains waters but also has good drainage so that the vine roots don’t become overly saturated. The ability of the soil to retain heat and/or reflect it back up to the vine is also an important consideration that affects the ripening of the grape. The composition of the soil has an influence on soil temperature, root penetration, water holding capacity, and vine nutrition.
Poor soil produces sturdier vines. Such soils, though deficient in nitrogen it may he rich in minerals; typically producing lower fruit yields but with greater concentration of flavour resulting in better wines. There are several minerals that are vital to the health of vines that all good vineyard soils have. These include calcium which helps to neutralize the Soil pH levels, iron which is essential for photosynthesis magnesium which is an important component of chlorophyll nitrogen which is assimilated in the form of nitrates, phosphates which encourages root development, and potassium which improves the vine metabolisms and increases it health for next year’s crop. While subsoil always remains geologically true, topsoil composition can be enhanced using manure or fertilizer.
Typical soil types in vineyards include chalk, limestone, slate, gravel, alluvial, clay, pebbles, volcanic, schist, sand, etc.

CLIMATE

The optimum weather during the growing season is a long, warm summer that allows the grapes the opportunity to hilly ripens and develops a balance between the acid and sugar levels in the grape. Microclimate prevails in single vineyards or within small regions. Rise and fall of terrain, location besides water bodies like lakes or rivers, presence of hills, mountains or forests as wind breakers are some determinants of microclimate, Beneficial conditions are responsible for certain vineyards having outstanding reputations.

Climate strongly influences the composition of mature grapes. A major cause of the variation among grapes from different areas is the differing quantities of heat received by the vines during the growing season. Other important factors include differences in night and day temperature, hours of sun, and soil temperature.

The ripening period in the Northern Hemisphere is from June to September, and in the Southern hemisphere from November to February. A lack of sunshine during this period produces less sugar in grapes. Too much towards the end of ripening will dilute the sugar in the grapes. Hail may damage vines, causing berries to split, causing unwanted moulds to form and grapes to spoil. Heavy mists or rain may affect delay harvest or encourage grey rot (mould) rendering the grapes useless. If the winter is not cold enough, many diseases and pests will survive and produce problems in the following year.

TEMPERATURE

In these winds the annual mean temperature are between 10°C and 20°C the presence of large bodies of water and mountain ranges can have positive effects on the climate and vines. Nearby lakes and rivers can serve as protection for drastic temperature drops at night by releasing the heat it has stored during the day to warm the vines, Rivers may raise the ambient temperature one or two vital degrees.
Diurnal temperature, variation is a viticultural term that relates to the variation in temperature that occurs from the highs of the day to the cool of nights. Wine regions situated in areas of high altitude experience the most dramatic swing in temperature variation during the course of a day. In grapes this variation has the effect of producing high acid and high sugar contents as the grape & exposure to sunlight increases the ripening qualities while the sudden drop in temperature at night preserves the balance of natural acids in the grape .

FROST

This is the most feared climatic condition. Frost in late spring will damage the new shoots, thus reducing the size of the crop. Methods to combat frost include propeller based rind dispersers to disturb the air (frost will only occur in still conditions), setting burning stoves (smudge pots) between rows of vines to beat the air, and aspersion- repeatedly spraying vines with water to keep them above O° C.

-HEAT SUMMATION/ SUNSHINE

Depending on the variety of the grape, around 85-100 days of sunshine are required from flowering to harvest. The vine needs approximately 1300-1500 hours of sunshine during the growing season. Grapes begin their growth cycle in the spring when average daily temperature is about 10° C (50° F). To reach maturity, they require a certain amount of heat above 100 C during the growing season. This amount of heat, called the heat summation, is calculated by totalling the number of degrees of average daily temperature over 10° C for each day of the growing season. A heat summation of about 1,800° is required for successful growth. If the heat summation is less than required, the grapes will not ripen; they will reach the end of the growing season with insufficient sugar and too much acidity. This condition, frequently occurring in the eastern United States, Switzerland, and other cool regions, can be corrected by adding sugar to the crushed grapes. Where the heat summation is much greater than required, as in Algeria and parts of California, the grapes mature earlier and with less acidity and colour than those produced under cooler conditions.
Factors influencing the heat summation of a vineyard and, therefore, grape composition include exposure (in Europe, best from the east), air drainage (preferably from the slopes to the valley), soil temperature (above 10° C during the growing season), and soil moisture content (not too dry at any time and not waterlogged for more than short periods).

Seasonal conditions also can be critical, especially in regions of low heat summation, as found in parts of France and Germany. When the growing season in such areas is warmer than usual, the fruit produced is riper and better balanced than is usual in cool seasons. In warm regions the sweeter dessert wines may benefit from somewhat low heat summation, resulting in less berry raisining (moisture loss) and giving the fruit better colour and acidity than is achieved when the growing season is excessively warm.

HUMIDITY

60-80% of humidity is desirable Excessive humidity encourages problems such as powdery mildew and grey rot.

-RAINFALL

Around 27 inches of rainfall throughout the year in order to produce grapes are suitable for winemaking. In ideal circumstances the vine will receive most of the rainfall during the winter and spring months. Rain during the harvest time can create many hazards such as fungal diseases and berries splitting.

Hazards

There are many hazards that a viticulturist needs to be aware of when growing vines. These hazards can have an adverse effect on the wine produced from the grape or kill the vine itself. When the vine is flowering it is very susceptible to weather hazards such as strong winds and hail.

Viticultural hazards include:

• Cidium
• Frost
• Hail
• Powdery mildew
• Downey mildew
• Phylloxera
• Plant virus
Millerandage is a French term referring to a viticultural problem in which grape bunches contain berries of greatly different size and, most important, different levels of maturity, producing clusters with no seeds and varying sizes. Its most common cause is too cold or otherwise bad weather during the flowering stage of wines. The condition causes lower quality in affected wines, which are often French or German.
Coulure (pronounced coo-LYUR) is the French word for the result of metabolic and weather conditions that causes the failure of the grapes to develop after flowering. In English the word shatter is used. This condition may occur due to extended rains or frigid weather during the flowering season. It also occurs in vines that have little sugar content in their tissue. Flowers stay closed and are not fertilized. Thus the vines are not pollinated and the grape fails to develop and it falls off. Coulure can also cause irregular bunches of grapes which are less compact than normal. These bunches are more sensitive for diseases. The yield of a vine with coulure will decrease substantially.
Coulure is triggered by periods of cold, cloudy, rainy weather or very high out-of-season temperatures. The condition is manifested in the spring. Varietals with high proclivity to coulure are Grenache, Malbec, Merlot, and Muscat Ottonel. Other causes of coulure may be vineyard conditions and practices, pruning too early or too severely, excessively fertile soils or overuse of fertilizers, and improper selection of rootstocks or clones.
Botrytis cinerea is a fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as Botrytis bunch rot; in horticulture, it is usually called grey mould or gray mold. The fungus gives rise to two different kinds of infections on grapes. The first, grey rot, is the result of consistently wet or humid conditions, and typically results in the loss of the affected bunches. The second, noble rot, occurs when drier conditions follow wetter, and can result in distinctive sweet dessert wines, such as Sauternes or the Aszú of Tokaj.

STRUCTURE OF THE GRAPE

The grape is made up of the stock and the berry. The stalk contains 78 to 80 percent of it’s weight in water, 2 to 3.5 percent tannin, 2 to 2.5 percent of other minerals and substances.
GRAPE SKIN—The berry comprises skin accounting for 11 percent of the weight, the pips 2 to 6 percent of the weight, the pulp 83 percent. The skin protects the contents and posses water repellant chemicals. The skin comprises 78 to 80 percent of water and 1 to 2 percent tannin. The skin is also attractive to retains natural yeast enzymes that will be found in the vineyard and that are essential to fermentation.
PIGMENT—The skin contains coloring matter. In almost all back grapes the pulp is white and the skin is coloured. In a few cases the the skin and the pulp has colour and such grapes make heavily coloured wines and are used mostly for blending but increasingly such grapes can make powerful varietal wines of greater structure. “Alicante Bouchet” is such a variety and the whole range of such varieties are called “teintures”

TANNINS—

Natural minerals found in the skins of black grapes. These have a great influence on the taste
of the wine. Tannins give an impression of dryness. They give both body and keeping quality to a wine and are essential in a red wine. Care must be taken to make sure that there is never an excess of tannin in a wine. Excess tannin can be caused if stalks are left for too long in the vats during fermentation and if stalks and skins are pressed too hard. White grapes do not have tannin but some tannins can be added to the white wine through oak fermenting or ageing or adding stalks to the crush.
STALKS—Most wine makers de- stalk the grapes before crushing or pressing although some wine regions such as Burgundy prefer to add some stalks to the crush. The pips are not used for wine making because if they are crushed they will add bitter oils to the wine.Modern crusher de- stalker machines will separate the pips out, these are collected, dried and crushed into farine, a form of flour which is used in the food production industry.

PULP—

The pulp contains 78-79 percent of water, 10 to 25 percent of sugar, 5 -6 percent of acids minerals, pectines and other materials. The sugar in the grape are equal mixture of glucose and fructose. They are necessary for fermentation.

ACIDS—

Acids are the most important factor in keeping the wine especially the white wine. and a balanced acidity is essential. Acidity gives freshness, brilliance, it is necessary in alcoholic fermentation, it prevents bacteria.
The main acids are Tartaric acid, Malic acid ( gives a sour taste) and citric acid. Malic acid is broken down by bacteria into lactic acid to the benefit of the wine ( called Malo-lactic fermentation) . Most of the citric acid is lost during the fermentation. Wines from cold climate countries are high in acid, those from warm countries are low in acid.