White wine

White wine is a wine that is fermented without skin contact. The colour can be straw-yellow, yellow-green, or yellow-gold. It is produced by the alcoholic fermentation of the non-coloured pulp of grapes, which may have a skin of any colour. White wine has existed for at least 4,000 years.

The wide variety of white wines comes from the large number of varieties, methods of winemaking, and ratios of residual sugar. White wine is mainly from "white" grapes, which are green or yellow in colour, such as the Chardonnay, Sauvignon blanc and Riesling. Some white wine is also made from grapes with coloured skin, provided that the obtained wort is not stained. Pinot noir, for example, is commonly used to produce champagne.

Among the many types of white wine, dry white wine is the most common. More or less aromatic and tangy, it is derived from the complete fermentation of the wort. Sweet wines, on the other hand, are produced by interrupting the fermentation before all the grape sugars are converted into alcohol; this is called ''Mutage'' or fortification. The methods of enriching wort with sugar are multiple: on-ripening on the vine, ''passerillage'' (straining), or the use of '' noble rot''. Sparkling wines, which are mostly white, are wines where the carbon dioxide from the fermentation is kept dissolved in the wine and becomes gas when the bottle is opened.

White wines are often used as an '' apéritif'' before a meal, with dessert, or as a refreshing drink between meals. White wines are often considered more refreshing and lighter in both style and taste than the majority of their red wine counterparts. Due to their acidity, aroma and ability to soften meat and deglaze cooking juices, white wines are often used in cooking.

History

Antiquity

The first trace of wine that has been found dates to 7500 years ago, in present-day Iran but the results of archaeological excavations have not been able to determine from which time wine began to be produced. Epigraphy tells us about the presence of wine in the Middle East: it was produced in the "High Country" (the mountain borders between Anatolia and Armenia) and then imported into Mesopotamia especially from the 3rd millennium BC. The tablets of Hattusa describes wine with the term ''wiyana'' in the Hittite language, GEŠTIN in Sumerian,A convention in Assyriology is to transcribe Sumerian in capitals and Akkadian in small italic letters to differentiate them. and ''karânu'' in Akkadian. It could be red (SA₅ GEŠTIN), light (or maybe white: KÙ.BABBAR GEŠTIN), good wine (DUG.GA GEŠTIN), honeyed (LÀL GEŠTIN) new (GIBIL), or sour (GEŠTIN EMSA).

In Ancient Greece wine had already been developed and used since Hippocrates, a physician born around 460 BC who commonly prescribed it to patients. "Vinous white wine" and "bitter white wine" were usedp. 46 among his remedies – a sign of diversity in production at that time.

In Roman times the type of viticulture practiced by the Greeks was their model; production included white wine. Rich Roman patricians organized banquets where the cost of the food was a sign of prestige. In the range of expensive products wine played a predominant role. The richest citizens built sumptuous villas in the Bay of Naples where the vine had been cultivated since its introduction by the Greeks. The ''aminum'' or ancient grape produced a sweet white wine produced as mulled wine resembling modern-day Madeira.p. 62 The conquering of regions more and more to the north encouraged the Romans to cultivate the vine and to produce lighter and less sweet wines. It also encouraged them to seek new wild varieties adaptable to these distant areas where the Mediterranean varieties showed their limits. For example, vines were planted on the banks of the Rhine to provide the Legions with a healthy drink, as opposed to water which was rarely drinkable. The wine was drunk cool in summer and warm in winter, a practice which still continues in the 21st century.p. 113

Middle Ages

Wine merchants failed to survive the fall of the Western Roman Empire and viticulture declined dramatically. The Germanic tribes preferred to drink beer and did not see the value of the wine trade. The decline of viticulture was intensified when Vikings cut the sea lanes in the Atlantic. In the south the Saracens were making '' Ghazw'' or raids. These campaigns in southern Europe caused Languedoc, Provence, Southern Italy, and the Douro Valley to become depopulated – the people being taken into slavery or fleeing the threat.

Knowledge about the culture of grapevines was conserved by the Catholic Church: wine was necessary for the celebration of Mass and the monks planted vines at high latitudes and increased the monastic acreages. Difficult to transport and store, wine long remained a product for local consumption. The trade was re-established initially after the enrichment of the nobles and prelates because, as with the Romans, the art of the table reflected the reputation of the host.p. 129-137

River trade was of great importance in the development of vineyards. The Germanic countries benefited from the navigability of the Rhine and the Danube so they could export their production. Charlemagne contributed to this growth by enacting his ''Capitulare de villis'' which included a set of rules on the cultivation of the vine in all areas. It was an era of great development of the culture of white wine in Germany and Austria. The Central European vineyards reached 100,000 hectares, which was three and a half times the area in the 1990s.p. 12-13 From the 13th century traders distinguished ''vinum hunicum'' (wine of the Huns), which was drunk by the people, from ''vinum francium'' (Wine of the Franks) which was the wine for the wealthy aristocracy. There was recognition of varieties of Rieslingp. 220 and Sylvanerp. 238 from the late Middle Ages.

Part of European trade was by sea along the Atlantic coast. The English, then the Dutch and Scandinavians''History of cognac''
, Bureau National Interprofessionnel du Cognac, consulted on 29 April 2010 from their demand for wine, created a craze for planting between Bordeaux and La Rochelle. Little dry white wine was produced for export from La Rochellep. 141-142 while Bordeaux exported mainly wines from the hinterland received via the Garonne. When wine production was introduced on the banks of the Charente in the 17th century, Charente white wines were introduced as cognac. At the same time, the dry white wine popular with the Dutch was produced to the north, around the port of Nantes from the current areas of Muscadet AOC and '' Gros-plant AOVDQS'' in the Loire Valley. Vineyards in the Loire Valley and the South-west had their sales network thanks to the navigability of the Loire and the Garonne.

In the Mediterranean Basin the Crusades greatly enriched both rival republics of Venice and Genoa. To supply the troops of the rich Frankish lords these republics provided them with wine from Greece. The port of Monemvasia, which exported a large amount of white wine, gave its name to the variety Malvasia.p. 153-154 The Crusaders also discovered Muscat wine. Once back home, the rulers and wealthy aristocrats looked to buy the sweet wines they enjoyed in the East. They came from grapes that dominated the vineyards of Languedoc-Roussillon and Spain. Trade in these wines was facilitated by their high alcohol content which ensured preservation during the long journey to Northern Europe.

Modern era

In 1453 the Ottoman Empire took Constantinople and the situation of the Venetians and Genovese deteriorated. The wine trade between the eastern Mediterranean and northern Europe fell sharply.p. 171 At the same time, the Spanish had just completed their ''Reconquista'' and replaced the Mediterranean wine with its own, especially for English and Dutch consumers. The port of Sanlúcar de Barrameda began to export large quantities of white wine which was the ancestor of today's sherry. This wine was called ''sack'' and caused a sensation in England. Even at the height of animosity between the two countries (as in the episode of the Spanish Armada in 1588) the trade continued – sometimes provided by pirates who stole what they could not buy. Between 40 and 60 thousand barrels each of 500 litres left the Spanish coast annually for England and the Netherlandsp. 173 (this volume of some 300,000 hectolitres represented two-thirds of today's production).

From the 16th century the first European vines were planted in America: in Mexico, then Peru, Bolivia, Argentina, and Chile. These were in addition to the native vines which grew in Mexico but this pre-Columbian production was not for the production of wine as the grapes were too acidic. It was used to produce ''acachul'' a drink sweetened with fruit and honey.

The Little Ice Age spelt the death knell of northern viticulture. The vine disappeared from northern Germany and Baden, and the maximum altitude for viticulture descended to 220 metres. Hans-Jürgen Otto noted that: "all the vineyards suffered and decreased in area". In England the vine also disappeared. The less early vineyards preferred to select white varieties of grapes because, even if unripe, white grapes allowed wine that was a little sour to still be consumable, while red grapes do not give enough colour and green tannins make the wine bitter. The interruption of the fermentation by a cold winter led to the discovery of the process of secondary fermentation of champagne.

The enrichment of some of the population created a craze for rare wines. This phenomenon, which was already responsible for the development of sherry in England, was reproduced in Central Europe. The discovery of the benefits of the noble rot on white grapes took place around 1650p. 232 in Hungary for the development of Tokaji wine. Hugh Johnson declared that: "the Tokay of three centuries ago was the best sweet wine in the world, it was inherited from a long-standing winemaking tradition".p. 235 Developed with a grape whose exceptional maturity is due to a trade secret, this wine is also developed its qualities through a process which long remained a secret in underground cellars of the winery. Prized by the House of Habsburg, Tokay experienced profitable trading. Attempted imitation came to nought and the use of noble rot remained a secret. It was not until 120 years later that a method of very late harvest was experimented with on the steep banks of the Rhine. Its use in Sauternes was attested in 1836 in the Château La Tour Blanche but at that time very late harvest gave a very rich wine that required several years to age in barrels.p. 264

Other regions were discovering secrets which would make them rich. So it was that Dom Perignon was the legendary creator of champagne.p. 210 In a northern vineyard he developed a special wine that would give rise to an exceptional passion for wine produced in a climate where it could not be expected for wine to reach maturity nor sufficient colour.

The fashion of drinking cheap dry white wine started in Paris in the 18th century. To evade the excise duty, Parisians took the habit of going to drink their wine at the producers premises outside the walls of the city. Cabarets opened their doors by the river, becoming Guinguettes (similar to taverns): so the wine that was drunk there was also called "guinguet". This is a wine from the hills of the Seine or the Marne, sour, but the conditions of transport of the time did not allow it to be used prematurely.

Contemporary era

Champagne was created in the 18th century but it was in the next century that its global expansion would occur. The crowned heads of Europe quickly made the wine stylish in their courts although its production, necessarily in bottles, made for a very expensive product. Historian Hugh Johnsonp. 331 assigns an important diplomatic role to champagne: Talleyrand would have offered this wine at the negotiating table of the Congress of Vienna, using it to relax his partners in the discussions. The occupation of Champagne by Russian troops in 1815 publicized the sparkling wine to the Russian aristocracy. The ''Veuve Clicquot'' (Widow Clicquot) booked her wine to her occupants saying "they drink today, tomorrow they will pay..."p. 335

The progress of the glass industry (especially from the use of coal) helped to democratize the use of the glass bottle. The production of sparkling wine increased dramatically and spread to the American continent. The technique of manufacturing was industrialized and other regions were inspired but the reputation of champagne suffered. The commercial flight of champagne was a product of the Industrial Revolution that allowed it to be within the financial reach of the emerging middle classes.p. 339

The period of the 19th century before the arrival of phylloxera was a golden age of wine. The Industrial Revolution enriched a bourgeoisie clientele for the best wines and the rural exodus to factories created a large market for mass-produced wines. A prominent example for white wines was the viticulture in Germany. The feeling of freedom infused into the German winemakers under French occupation during the First Empire prevented the aristocracy and the clergy from recovering all the vineyards from which they were dispossessed.p. 395 The practice of late harvest was widespread and the more or less sweet wines gained balance against their always lively acidity. In 1872 the Geisenheim Grape Breeding Institute was created and it was the source of a great amount of interbreeding giving new varieties – the best known of these is the Müller-Thurgau.p. 396 During the same period, Switzerland adopted, along the shores of Lake Geneva, vineyards predominantly producing white wine.

During the 20th century planting vines in countries where it was unknown was booming. However, it was shaky in places with higher temperatures during fermentation.p. 450 The use of larger containers creates problems during fermentation: the yeasts produce heat which cannot escape and beyond 35 °C the micro-organisms begin to suffer and fermentation slows then stops. After cooling the wine a new addition of yeast is needed to resume fermentation (not to mention the adverse effects on the wine's aromas and the risk of ''lactic bite''). In California the search for temperature control of fermentation matured. Applied to white wine they revolutionized this type of wine. European wines, marked by their processes of crushing the grapesp. 397 are diametrically opposed to those very fruity wines marked by a refreshing liveliness. During the years 1960–1990, these methods of wine-making moved to Europe and the use of refrigeration equipment is now widely used in almost all regions producing white wine.

Geographical distribution

Production

Climatic zones

Many wine-producing countries produce white wine, however the white grape needs less heat than red grapes to ripen: the lack of maturity of tannins is not a problem since they are not extracted in pressing. In addition the taste balance is based on a significant liveliness due to the acidity. The grapes for the production of dry white wine are harvested just before ripening. These production conditions can result in a more northerly or mountainous location for the vineyard producing dry white wines.

In Europe, German vineyards are predominantly white (63.1% of production area in 2006), as are the Swiss vineyards (more than 50% of the area in production are white grapes) and the Luxembourg vineyards (93% of the production area in white or grey grapes). In France the northern half produces most of the white wines (Alsace, Jura, Champagne, and the Loire Valley). In Spain, paradoxically, Castile-La Mancha accounts for 50% of the Spanish vineyards, producing mostly white wine on a very large production area in a high temperature zone. The Catalonia region produces a lot of white grapes which are transformed into Sparkling wine called '' Cava''. The producing area for Cava is 45,000 hectares out of a total producing area of 65,600 hectares.

The Americas have developed both white and red wines, some of which are now recognized worldwide. White wines have to conquer hostile territories where red wine dominates, such as the Rocky Mountains or Canada. In Canada, the technique of ice wine can produce exceptional wines in a climate which is apparently unfavourable. Canada is the largest producer of ice wine in the world.

The warmer southern areas also produce white wine, but in a lower proportion. In addition, it is more often sweet or fortified wines, natural sweet wines or "vinés" wines,The "Wine viné" is one in which alcohol is added after fermentation, wine "muté" has alcohol added during fermentation, and the wine "liqueur" has alcohol added before. Se
"Wine muté"
, Grand Terminological Dictionary, Office québécois de la langue française, 2006, consulted on 27 December 2010 . as in the case of vineyards around the Mediterranean (muscat, madeira, marsala etc.).

Geological zones

According to Claude and Lydia Bourguignon, red wines are well suited to soil based on limestone while the best white wines are produced on soils over metamorphic rocks (Alsace, Moselle, Anjou) or volcanic rocks (Tokaj in Hungary and Slovakia).

In addition, white wines are also produced on land with a limestone sub-soil such as the chalky base of the Champagne wine region or the limestone under siliceous marl of Chassagne-Montrachet form the backdrop to some of the most prestigious wines in the world.

Grape varieties

Numerous varieties of grapes can be used to develop white wine.

Some have achieved a strong reputation thanks to their marketing of a wine variety:
* Chardonnay :The International code designating the variety indicates the colour of the grape:: B = white (blanc), N = black (noir), Rs = rose, G = grey. originating from Burgundy and long sold under that name under the communal AOC or premier and grand crus, it has spread to many new producing countries who sell under the name of the grape. It can be made sparkling or still. It typically has a wider-bodied and rich citrus taste compared to other white wines. A common choice of food pairing for this wine is fish or poultry. It owes its world distribution to its quality in a very wide variety of regions of climate and geology: from France to the United States, Australia, and South Africa
* Sauvignon blanc : originating from the centre of France and the Bordeaux vineyards, it then spread to the vineyards of the South-West and the Loire Valley. Noticed by Anglo-Saxon consumers, it spread to growing regions in the United States, Australia, New Zealand, and South Africa. It is remarkable for its typical vegetable/mineral aromasp. 230-231. so tends to be flat and lack fruit qualities. The dominating flavours range from sour green fruit such as of apple, pear and gooseberry through to tropical fruit such as melon, mango and blackcurrant. A common food pairing for this wine is seafood, poultry, and salad.
* Riesling : originates from German vineyards (Germany, Alsace, Switzerland). It is a grape that can be of high quality in a variety of soils provided that yield is limited and climate tends to a continental climatep. 220-221. This type is much lighter in comparison to other white wines and typically has a green apple aroma. Common food dishes that go well with Riesling are fish, chicken, and pork.
* Müller-Thurgau : the most widely grown grape in Germany which gives a fruity and well-balanced wine but that cannot be kept very longp. 172-173.
* Muscat : a group of varieties (over 150 according to Pierre Galet) which have specific aromas. Typically made from Italian and Austrian grown grapes, it can offer a sweet and fruity taste. Shows best on its own without a food pairing.
* Petite Arvine , originated in the Valais in Switzerland. Historical documents reveal it has been grown since the early 17th century, around 1602. Typically medium-dry, this textured wine contains a generous amount of extract from its thick-skinned berries. Highly regarded by modest vintners, it has become the most frequently grown wine in the most prominent wine-growing region of Switzerland. The variety is often paired with central and northern European foods.

File:Chardonnay.jpg, Chardonnay grapes
File:Riesling grapes leaves.jpg, German Riesling B grapes at maturity
File:Sauvignon blanc grapes.jpg, Sauvignon blanc
File:Gelber Muskateller Weinsberg 20060908.jpg, Small white grapes of Muscat B

Other grape varieties are less well known as they may be marketed under an ''Appellation'' or mixed with other varieties:
* Airén : a little-known variety, yet it is the most planted vat wine in the world with 390,000 hectares. It is second only to the sultana. Grown almost exclusively in Spain, it is planted in a low density and produces a dry white wine consumed locally
* Catarratto bianco comune : a grape from southern Italy, it gives an aromatic and high alcohol (14% of volume) wine. It is one of the varieties of grape used to produce Marsala and Madeira
* Chenin blanc : a French grape from the Loire Valley, it is also grown in South Africa. It yields a very fruity wine, sometimes mineral, dry, or sweet depending on the soil. It can be kept for a long time and take on the noble rotp. 96-97.
* Maccabeu : a Spanish grape, it is used to develop Cava, the Spanish sparkling wine. It is also grown in the vineyards of Languedoc-Roussillon in France. Its wine is dry and fruity and yields a Fortified wine
* Sémillon : a grape originally from Bordeaux vineyards, it is the main variety used for sweet wines from Bordeaux and Bergerac due to its ability to take the noble rotp. 235-236. It possesses a fig-like characteristic and is often paired with Sauvignon blanc to mellow its strong berry-like flavours.
* Trebbiano bianco or Ugni Blanc : an Italian grape variety giving a fairly neutral wine. In France this wine is usually distilled to yield cognac or armagnacp. 256-257.
* Viognier : a French grape from the Rhône Valley, it has been planted in California since the 2000s. It yields a very fruity and complex winep. 269.
* Grenache blanc : this is the white form of Grenache black N. A variety of quality, it produces fine full-bodied dry wines, albeit with sometimes deficient acidity. It also provides natural sweet wines of high quality.p. 143

File:AirenGrapeVine.jpg, Grapevine of Airen, the most planted vat grape in the world.
File:Chasselas B.JPG, Chasselas, for vat and table wine.
File:Chenin blanc grapes.jpg, Chenin .
File:Trebbiano-Uva bianca per Vino Falerio delle Marche.jpg, Trebbiano blanco or ugni blanc B.

Some varieties with coloured skins are also used to produce white wines:
* Gewürztraminer : this grape has a pink skin. Vinified in white, this is a very aromatic grape with typical aromas reminiscent of pink flowers and lychees. It is grown all over the Alps. It is an aromatic mutation of Traminer (in German ''gewürzt'' means "spiced")
* Pinot noir and Pinot Meunier : these grapes are used for the development of champagne and rose wines
* Pinot gris (Pinot grigio) is planted extensively the Venice region of Italy. The colour of these grapes range from a copper yellow to light pink. It typically has a crisp fruity flavour which allows for a versatile food pairing.
* Sauvignon gris : used to make rosé from Sauvignon blanc, it has a superior richness in sugar and heavier aromas. It is particularly well suited to the production of sweet winesp. 234
* Grenache Gris : this is the rosé form of Grenache. It is used in the amber versions of Grenache from Rivesaltes AOC, a natural sweet wine white with a darker colour from oxidation.

File:Gewürztraminer.jpg, The Gewurztraminer grape variety with a pink skin which produces a white wine.
File:Pinot Meunier.jpg, Pinot Meunier, a black grape widely used for white or rosé champagne.
File:IMG Pinot Noir 1.JPG, Pinot Noir, a black grape used for the production of white wine.

Components of the grape and the

must

The stalk

The stalk (or ''rafle'') is the herbaceous branch that bears the grapes. It consists of about 80% water, soluble minerals (nearly 3% with half of potassium) and polyphenols. The polyphenols are mainly tannins and are responsible for the bitter taste and the sensation of astringency. In the production of a white wine, the stalk does not contain any useful part: its moisture can cause dilution and the presence of tannins is not desirable in the wine. This is why it is quickly isolated from the rest of the harvest, either by shaking or by pressing.

The grape berry

The grape berry is made of skin, flesh (or pulp), and seeds. The seeds are hard and are 2 to 5% by weight of the berry. The seeds contain 25-45% water, 34-36% carbohydrates, 13-20% fat (the grape seed oil), 4-6% tannins, 4-6.5% protein, 2-4% minerals, and 1% fatty acids.''Chemistry of the Vine. The essential material: the grape''
Pascal-Antoine Christin, 2004, futura-science, consulted on 19 March 2010 Their contribution in white wine is zero since they are removed in the pressing, in addition, the pressure is insufficient to extract anything from the seed.

The skin is 6-12% by weight of the grape. It is coated on the surface with Pruinescence, a waxy coating that gives a matte finish to the colour of the grape and contains the yeast responsible for fermentation. The grape skin also contains volatile compounds in its deeper layers. These are responsible for the aroma of the grape and for the molecules that become the aroma of wine during fermentation: they are the "aroma precursors". In red grapes the film also contains anthocyanins or coloured matter which is from bright to purplish red. To produce white wine from red grapes it is necessary not to macerate the grapes, nor to press too hard on the harvest to avoid the dissolving of the anthocyanins in the grape juice. The skin contains a lot of cellulose, insoluble pectin and proteins, and organic acids: citric, malic, and tartaric acids. The skin of the Sauvignon blanc B grape has a pH of about 4.15. It also contains between 2 and 3% tannins.

The flesh of the grape is the most important part – it is between 75 and 85% of the weight of the grape. It consists of large polygonal cells which are very thin-walled. With a low pressure the cells leak their contents: the wort. The flesh of the grape contains mainly water. The organic components are fermentable sugars (between 170-230 grams for a dry wine and between 200 and 300 grams per litre or even more for Fortified wines) and organic acids, especially malic acid and tartaric acid. Acids occur in larger amounts in the centre of the berry while the sugars are in greater proportion at the periphery. This heterogeneity in the distribution of sugars, acids, and inorganic compounds in the berry is used during pressing, especially in Champagne pressing. This process separates them as it happens and uses them to measure the progress of the "vintage", the first and second ''tailles'', and finally the ''rebêches'' of insufficient quality to be made into AOC wine.

The flesh is the major element of the wine, as it is the part that contains the highest proportion of liquid. The flavours are much less present than in the skin.

The wort

In the case of white winemaking the wort is simply the grape juice from the pressing of grape berries.

The sugars

Sugars are carbohydrates derived from photosynthesis. The sucrose is made in the leaves and flows into the plant where it is broken down into glucose and fructose and accumulates in the berry where it is a characteristic of the maturation of the grapes. Many different sugars coexist: the most common are glucose and fructose which will be consumed by anaerobic yeast to convert it to alcohol during fermentation. They are in substantially equal amounts. To verify the completion of the fermentation they can be quantified by chemical assay (glucose and fructose are "reducing" sugars that react with an alkaline copper solution called Fehling's solution), an enzymatic method, or by infrared spectroscopy.

Other sugars are not fermentable at all. After consumption by the yeast, the ratio of non-fermentable sugars (the ones that are not consumed by yeast: arabinose and xylose) is between 0.5 and 1.7 grams per litre. Sugars exercise a control over the taste – they balance the spiciness of the acidity and the burning of the alcohol.

The organic acids

The organic acids are mainly malic and tartaric acids. Tartaric acid is a characteristic of grapes; in its leaves its content ranges from 5 to 7 grams per litre. Malic acid is present in green grapes and its ratio decreases with maturation to give between 2 and 7 grams per litre at harvest. The range is very wide depending on the variety and soil with hot climates giving lower rates as the heat accelerates its degradation. There are many other acids in small quantities: citric acid, ascorbic acid, α-ketoglutaric, fumaric acid, galacturonic acid, coumaric acid, etc. Their variable quantity varies the pH of the wort. The must of white wine is generally more acidic than red grape must simply because the grape maturity is less advanced.

Vitamins

Vitamin C (or ascorbic acid) is present in the grape and the must up to 50 milligrams per litre. It is a protection in the wort against the oxidation phenomenon. In the presence of oxygen it produces hydrogen peroxide; by this reaction it deprives the enzymes in the wort of oxygen that is necessary to oxidize the wine. Since 1962 the addition of vitamin C in the wine has been allowed to a maximum of 15 grams per hectolitre at the time of packaging to stabilize the wine. Experiments in the late 2000s tried to determine a method to add it to fresh harvests or in the wort.

Vitamin B1 or thiamine is present at a concentration between 0.2 and 0.5 milligrams per litre. This vitamin is necessary for the proper growth of yeasts that ensure alcoholic fermentation. In the must of healthy grapes the natural quantity is sufficient for the yeast. On the other hand, for a degraded harvest (by gray mold), the degradation of this vitamin leads the winemaker to add it to the must to ensure a trouble-free fermentation. In the case of a harvest with a very clear wort and low temperature the yeast works in a limited way and the addition of thiamine can help avoid a difficult end of fermentation. Legislation limits the amount added to 30 milligrams per hectolitre.

The mineral elements

The wort also contains minerals. Sodium, Potassium, and Magnesium are most common. Potassium and also calcium can form salts with the tartaric acid: Potassium bitartrate and the neutral calcium tartrate at the pH of the wine. For these, when their solubility threshold is reached, they settle and contribute to de-acidify the wort. In the southern regions where acidity is sometimes a little lacking this may be a cause of failure of extra acidity.

Winemaking

White winemaking is broadly similar to red winemaking although details differ when making the two types.

White wine is made from white or black grapes (but always with white flesh, the grapes with coloured flesh are called ''Teinturier'' meaning coloured juice). Once harvested, the grapes are pressed and only the juice is extracted which is called wort. The wort is put into tanks for fermentation where sugar is transformed into alcohol by yeast present on the grapes.

The grape harvest

Grape maturity depends on the requirement of the final product. For a sweet white wine, whether fortified or natural, sugar is the key criterion. For a dry white wine, technological maturity is calculated and the fruit is harvested just before (usually eight days''The Procedures of Winemaking'', Science & Vie, No. 155, quarterly series, Jean-Luc Berger, September 1986, Éditions Exelsior, Paris, , pages 76-77, ) the maturity of the sugar. At this point the relationship between sugar and acid is optimal. Further, low acidity will cause the future wine to be unbalanced with excess alcohol and lack of liveliness. In addition, the flavour will be less fresh and less vivid.

Traditional hand harvesting of whole bunches has been increasingly challenged by the harvesting machine for dry white wines, an economic choice but not always a qualitative one. The fragility of the grape requires either a rapid transfer to the Winery, or protection from oxidation. When the transport time between vine and winery is long, the harvest can be refrigerated and kept away from oxygen using nitrogen or dry ice.

However, for some sweet wines, a successful harvest requires manual work and training for pickers to pick only clusters where the berries have reached optimum ripeness or have been affected by noble rot (for the ''Sélection de Grains Nobles''). For sparkling wines hand picking is recommended and it is absolutely necessary for white wines from grapes with coloured skin.

Treatments before fermentation

The first step in processing the grapes at the winery is to separate the components of the wort that are needed from the unwanted parts. The process followed at this stage will largely determine the future quality of the wine. For this, the clusters are generally shaken then trampled. The practice of moderate trampling allows the grains to burst, releasing the juice and pulp (it cannot be used for white wine from black grapes as the premature bursting of the berries would cause a coloured must). The practice of shaking or stalking has the advantage of separating the stems from the cluster of grapes and avoids giving the wine a herbaceous taste at pressing. The skin is not macerated and the transparent yellow colour is retained.

The winemaker can soak the skins of white grapes and practice maceration if the quality of the grapes is good. Pre-fermentation Maceration is generally performed at a controlled temperature to delay the onset of fermentation. This technique improves the extraction of varietal aromas and their precursors which are mainly located in the skin. Acidity decreases as does the ratio of Colloids (large pectin type molecules) and aging potential. To be implemented, this process requires a perfect de-stalking, moderate crushing and sulphite to protect the wort from oxidation. The duration (typically 5 to 18 hours at 18 °C''The Vine and the Wine'', Denis, Debourdieu, Chapter: White Wine making, Éditions la manufacture et la cité des sciences et de l'industrie, 1988, Lyon, , p. 170-171 .) depends on the variety, the temperature of maceration, the maturity of the grape, and the quality of the soil.

The trampled and de-stemmed harvest is then pressed. The type of wine press also affects the potential quality of the wine. Since the 1980s, pneumatic presses have improved the work involved by working in airtight conditions and allowing a fine control of the pressure to extract the juice without damaging the grapes. The juice or ''moût de goutte'' (Must of Drops) is the juice that flows naturally from the berries crushed under their own weight prior to pressing (on the way to the press). Trampling increases its proportion and makes the material profitable by processing a higher tonnage of grapes in the same time. The ''moût de presse'' (Must of the Press) is the juice flowing from the press from the pressure on the grapes. It concentrates the qualities or the defects of the grape: it is rich in aromas, colloids, or phenolic compounds. However, it can also be marked by olfactory defects, such as the smell of fungus on spoiled grapes or the vegetable smell of a harvest with insufficient maturity. The blending or not of the ''moût de goutte'' and the ''moût de presse'' musts and release depends on the health of the grapes, the method of pressing, and the style of wine intended. Manipulation of the grape before pressing increases the amount of lees and complicates pressing. For the development of a quality wine, their use is excluded or very limited.

The settling

The settling is intended to clarify the wort by removing the lees from it. The lees are colloids in suspension, debris from the skins or pulp, and exogenous debris (soil).

Static settling consists of leaving the must to let the debris settle: after pressing, the must is left to stand in a tank away from air. Suspended particles precipitate to the bottom of the tank. This is facilitated by the addition of pectolytic enzymes which are long chain carbons composed of pectic compounds. These pectins give a high viscosity to the juice, cut the suspended particles into shorter chains, and accelerate precipitation. Refrigeration of the wort is needed: if the fermentation starts, the release of bubbles of carbon dioxide would spread suspended particles throughout the wort preventing their deposition. After the wort is clarified it is decanted for fermenting.Settling
consulted on 1 January 2010

Dynamic settling is performed with a machine that accelerates the separation of the wort from the lees. The centrifuge removes the largest particles but does not achieve a high level of clarity.

Settling by flotation is a technique where the introduction of a gas at the bottom of the tank creates bubbles which cause the particles to rise to the surface where they are removed by a scraper. Filtration with a rotary vacuum filter is relatively slow but effective. It is often used to recover clear wort in the lees exiting the centrifuge.

In addition enzyme treatment can improve the settling of the Finings. Bentonite plays a mechanical role of ballast to settle the colloids – it accelerates the sedimentation rate. Gelatin is also used to flocculate the suspended tannins extracted by the press. Often associated with a bitter taste, their removal is generally beneficial for white wine. Polyvinylpolypyrrolidone or " PVPP" allows the fixing of polyphenols and eliminating them. These molecules are responsible for the browning of wine and their removal gives an element of stability in the future drink.

In the "stabilisation of lees" (liquid cold stabilization) the winemaker regularly adds lees in suspension for several days so they do not settle immediately. Then he proceeds to a conventional settling as indicated above. This technique allows the enrichment of the wort with precursors of "thiol" (passion fruit, citrus ...) which are naturally very soluble in the wort and are particularly suitable for some varieties such as Sauvignon and Colombard. In the "maceration of lees", the lees from the static settling are gathered in a refrigerated tank and agitated for several days. After filtration and fermentation they give a white wine also rich in thiols.

Muscadet