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Enology

Enology

Taste the difference!

If you want to avoid wine mistakes, you have to pay much more attention than just hygiene. While some wine growers access the entire spectrum of modern oenology, the others deliberately dispense with all possible interferences in the fermentation process.
More and more winemakers and wine merchants are specifying the fermentation process. Winemaking or vinification knows different processes and combinations for white and red varieties.

Macération semi-carbonique, or how it all started ...

This is probably the oldest method for red wine making ever. The wine fermentes by itself when healthy grapes are filled in a hermetically sealed container. Ancient Egyptians, Greeks, Georgians and Romans had the practical experience, but not our present knowledge, so the earlier wines had less alcohol. At the bottom of the tank are the crushed grapes, whose must produces CO2 by the incoming alcoholic fermentation. The naturally resulting CO2 fills successively the tank, which proceed through the respiration and reproduction of the yeast fungi. The fermentation lasts 10 to 20 days. These fruity wines are young drinkable without long barrel and bottle maturity. The well-known Beaujolais Primeur, Beaujolais Nouveau and Languedoc Roussillon benefit from this method.

A good example of the natural fermentation is the amphora wine from the Qvevri (Kwewri). In Georgia and Armenia, these terracotta pots were coated on the inside with beeswax, which made them waterproof and limed (malolactic fermentation) on the outside, placed in the ground (thermal stability) and sealed at the top with a lid, wood ash, birch tar and sand. Thus, only a much lower oxidation takes place. Such vessels are manufactured today with a capacity of up to 4,000 liters. Researchers estimate that this process is more than 6,000 years old and was used with vessels up to 15,000 liters. In a similar way proceeded the Romans with the pressed grapes, calling their vessels Dolia (Dolium), which were used for fermentation and storage. Such vessels up to 2500 liters were coated with pitch on the inside.

Fermentation and clarification are free of chemicals or other organic remedies. It requires a substantial complex infrastructure. The wine is available again, tastes very different than those we know from the European market. Was it possible to use this technique also with white wine? Yes, it was confirmed by the Alsatian winery (Domaine) Mathieu Deiss. The domaine presented the new Cuvée "Singulier 2015", which was composed from Riesling, Pinot Blanc, Pinot Gris and Pinot Noir and vinified by the carbonic maceration. The Cuvée has become a great success and offers pleasant aromas of fresh grapes, ripe mirabelle, as well as a nice orange color.

Macé­ra­ti­on car­bo­ni­que

During his wine- and fermentation studies in the 19th century, Louis Pasteuer found out that healthy grapes began to ferment under oxygen exclusion. He called the procedure "intracellular fermentation". He coined the expression -fermentation, c'est la vie sans l'air, which means fermentation is life without air.

Today, fermentation means any microbial or enzymatic transformation of organic matter, even under oxygen. In the 20th century, this knowledge combined with new technology was used to ferment whole berries in a container under CO2. This difficult fermentation by the grape-like enzymes takes about 7 to 14 days at over 25 degrees Celsius. Malic acid is thereby reduced and more amber and shikimic acid are promoted. This method is used in France for some of red grapes to obtain very fruity and aromatic wine (also cuvée). The wine with its characteristic fragrances of vanilla, caramel, clove, sweet clay (also called rum pot ), fruits or dried fruit contains less tannins. This method works well with grapes with soft berry skin and even with grape varieties rich in color and tannins. Who wants to achieve more than 2 vol.% alcohol, must continue with the alcoholic fermentation.

Alcoholic fermentation - traditional vinification by yeasts

Carbohydrates (sugar) are converted to ethanol (alcohol) with the aim of the yeast. It has the ability to consume energy from sugar breakdown either through respiration or through fermentation. As a result we get numerous by-products that are more or less welcome. The odorless gas carbon dioxide (CO2) escapes in the form of bubbles. As long as it bubbles, the must is still fermenting. The yeasts start the fermentation process at about 15 ° C. As a by-product of the yeast reproduction, alcohol is produced, depending on the heat of the must, faster or slower. When the sugar is used up, or the must reaches 15% volume of alcohol (only in extremely high-sugar musts), the yeast die, and the alcohol becomes enemy of the yeast. In general, the more sugar is converted into alcohol, the drier the wine becomes. White wines ferment about 3 to 5 weeks; the noble sweet white wines up to 3 months. The controlled aeration and temperature make various fermentation times (fermentation / vinification) possible. Red wines ferment in a period of 4 to 15 days. Only the Barolos or Cabernet Sauvignons are left on the skins for 4 weeks. If the fermentation gets stuck, a nightmare begins for the cellar masters.

A spectacular case was the 1992 Le Montrachet of the famous Domaine de la Romanée-Conti. The wine was never brought to market because it did not ferment and stayed sweet. This can happen with high-grade musts that should actually ferment. If the yeast dies, it falls to the bottom of the vessel, called the "tank bottom extract". Once the fermentations (alcoholic and malolactic) have been completed, the addition of SO2 eliminates all germs and protects the wine from oxidation during bottling.

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Yeasts

The yeasts originates from nature or from the laboratory. The yeast produced in the laboratory is called dry yeast and it has to reduce the risk of wine defects. Existing characters of the wines are lost by using it. There are some special yeasts that are designed for different temperatures and flavors. For example, there is an yeast selected for the Sauvignon Blanc to give the wine a soft or more aggressive flavor. The natural yeasts or wild yeasts grow around the grapes. They can be positively or negatively influenced by the weather. Wet, cold, strong wind, fruit flies and sprays can affected them. There are different strains of wine yeasts, which differ in taste and properties. They can react differently to the elements in the must, be sensitive to alcohol or heat or produce too much hydrogen sulfide (odor-blubber). When one strain dies, another yeast strain takes over the transformation. Due to the climate in California, South Africa and Australia, no yeasts are produced there. These countries use, such as more and more European wine producers, the pure yeast. In contrast, loyal winemakers in some parts of Europe still use the natural yeasts. These yeast strains produce complex, characterful wines. In vineyards, organic fertilizers are used by winemakers to support the yeast production. Sliced vine wood, pressing residues (trester) and the "tank bottom extract" are spread in the vineyards.

Mesh Fermentation

Red wine grapes undergo two fermentations in local vineyards. First, red grapes are destemmed (removing ot the stems), squeezed or ground to open the grape skin. In open fermentation vessels, the grapes are processed to allow the generated carbon dioxide to escape upwards. The processed grape berries (pomace) are transported up by the generated carbon dioxide. Juice, pulp, grape skin, stem remnants and grape seeds form the so called mash. Tannins from the grape skin (about 20-30% of all tannins) are the softest. They are also called the soul of red wine. Unnecessary tannins come from the stem fragments and grape seeds. After some days, the wine turns to dark red and the grape skin to bright purple because red wines ferment normally faster than the white wines (the mash contacts with oxygen and the yeasts multiply faster than under oxygen exclusion). By then, the pomace shall be in the mash. If it still rests on top, this step was useless. In France, the mash was traditionally done by hand or foot. The pomace shall be pressed down again and again or be sucked by a pump from the bottom and run over the pomace. Today, various rotary tanks are used to circulate the mash. In Germany, tanks with paddles are used in the interior. While grape seeds fall into a gutter by turning down, the grape skin gets seprated. When the fermentation process is over ( carbon dioxide is no longer produced), the grape skin, dead yeasts and pulp sink to the bottom. The temperature is decisive for the fermentation time. It is between 30 ° C and 35 ° C for red wine to extract the softest tannins. The fermented wine is drawn from the skin and can finally ferment. Low-color varieties like Lemberger, Trollinger or Pinot Noir are often briefly heated to 80 ° C in another vessel without grape skin in order to obtain more color. Grape skin, pulp particles and dead yeasts are pumped from the bottom of the vessel into a crusher and squeezed out. If there is still sugar in the liquid, it is further fermented without skin. Then the fermentation is over.

Cold Fermentation

Thanks to new white wine style, we´ve got a fresh, fragrant and pure wine. These finished wines are uncomplicated and have no distinctive varietal flavor. The low fermentation temperatures have a positive effect on the aromas and alcohol. High fermentation temperatures would cause the alcohol to evaporate and many flavors would disappear. Steel tanks are used in order to cool the previously well-clarified must. In the double-walled tanks, cooling coils run inside with the coolant glycol. The normal steel tanks are wetted surface with cold water. Normally fermentation starts at 15 ° C within 2 days. When the yeasts multiply, the temperature rises rapidly above 30 ° C. Cooling prevents it and keeps the mash temperature-controlled between 15 ° C and 18 ° C.

Cold fermentation uses special yeast strains, which allow the must to ferment even more slowly and for longer between 8 ° C and 12 ° C. It generates even more extreme fresh, clean-toned, attractive wines with crisp aromas. This type of fermentation is also possible in tropical countries. However, their white grapes often have too low acidity (high pH), even if they are harvest earlier. If the natural acidity sinks to less than 4 gr per liter, citric or malic acid is usually added. These procedures are called acidification. In Europe, acidification is rarely necessary and usually even prohibited. Because cold-fermented white wines do not have a distinctive varietal flavor and can hardly be assigned to a grape variety or a region, they also have opponents. Bad und unkind they are referred to by some as "tank wines". Moreover, fermentation under exclusion of oxygen often leads that the wines are particularly susceptible to oxidation. Such wines age relatively quickly in the bottle and become old soon.

Debourbage

Once the yellow-green grape juice flows, it should be further processed as quickly as possible due to the risk of oxidation. The must is full of dirt particles, cloudy and viscous. Some enzymes are added for clearing it. They dissolve the pectin and the must becomes thinner. The must is degummed and then fermented immediately. There is a risk that too much initial settling (debourbage) destroys valuable ingredients. That´s why some winemakers waive on this procedure. In most cases, freshly pressed must is pumped to a settling tank where it rests for up to 24 hours at 5 ° C or 8 ° C (not fermented). The solids sink to the bottom, the must is cleared. This method is gentle. In the case that the must oxidizes, it must be sulfurized. Some winemakers use centrifuges that can clarify over 10,000 liters of must per hour. This has the advantage of rapid further processing, while sulfur can almost always be waived. Big disadvantage is that not only different valuable ingredients such as yeast, colloids, etc. are lost, but the fermentation can only happen with organic yeasts.

white wine must contains:
70–85 %water
15–27 %carbohydrates (sugar)
0,3–1,8 %acid citric, malic and tartaric
0,3–0,6 %Minerals such as sodium, phosphorus, potassium, anions etc.
0,03–0,5 %proteins, amino acids
0,01–0,2 %polyphenols (tannins, dyes)
>0,01 %vitamins
vinum mustum- young wine / 1 kg of grapes yields about 0.7 liters of must

Malolactic Fermentation

While acidity is desired in a fresh white wine, red wines undergo lactic acid fermentation after alcoholic fermentation. Lactic acid bacteria are added to the must at 20 ° C to convert the malic acid into the milder lactic acid within 2 to 3 weeks. It is considered that the must is richer in taste and full-bodied through the malolactic fermentation. Once the fermentations (malolactic and alcoholic) are complete, the addition of SO2 eliminates all germs and protects the wine from oxidation during bottling.

Oak and barrels

Celts were the first who used wooden barrels for transport. Germans and Romans had taken on that artistry from the Celts. The hard oak wood is denser than most wood species and has spicy tannins. Only oak wood was used for making barrels.

French oak: considered to be tighter grained and less concentrated, with more delicate flavors and firmer.

Holm oak: is often used because of its fine oil, has a coarse grain, so wines stored in oak barrels would pick up a lot of flavor.

Fermentation in Barriques

In the French wine-growing regions of Champagne, Burgundy and Bordeaux, the solid, heavy white wines have always been fermented in oak barrels (small oak barrels). The fermentation temperature, which is usually between 23 ° C to 25 ° C, can not be controlled in such barrels. It produces ester complexes that provide more sulfites and the must takes a different flavor process than in the cold fermentation. As soon as special fermentation aromas are added, the must loses fruit. These include caramel flavors (butter and butterscotch), vegetable flavors (such as hay and pepper), tea and tobacco flavors or lactic flavors (cheese). High fermentation temperature bears the risk of activating harmful bacteria.

Aging in Barriques

To ensure the exchange of oxygen, the wines are gladly aged in small oak barrels, which ensure a fine oxidation. Such wine ages faster and develops different aromas than in an environment very low in oxigen. Light or medium weights wines are not or only slightly suitable for this expansion.

Chaptalization/ Rectified Concentrated Grape Must

is a highly concentrated sugar syrup made from grape must. In Germany it may be used for land and quality wines (Q.b.A) under certain conditions. For predicate wines (ex Cabinet) it may not be used. Addition of sugar increases the alcohol level. For more information BMEL.

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