How is rosé wine made?

In principle,rosé wine is made exclusively from red wine grapes, as the grape 's colouring agents(anthocyanins) are found in the berry skins. However, it is essentially produced in the same way as a white wine, as fermentation takes place after pressing(must fermentation). The main steps in winemaking after the grape harvest are short maceration, fermentation, pressing, ageing, fining and bottling.

All of the following steps and treatment processes are permitted under wine and food law. However, not all measures must be applied, as some are at the expense of the wine's variety of flavours, fineness, depth and balance.

Harvest

The time of harvest depends on the degree of ripeness of the grapes, the weather conditions and the desired type of wine. How quickly the grapes ripen depends on the grape variety and the weather throughout the year and especially in autumn. The grapes for Prädikat wines require a higher must weight and must therefore remain on the vine for a particularly long time.

The grapes are harvested either by hand or with the help of machines(harvesters). Mechanical harvesting is very quick and requires less labour, which is generally an economic advantage and also a very practical advantage if the weather is unstable or bad at harvest time, which can even save the quality of the wine. Negative selection often takes place beforehand, where grapes that do not fulfil the quality requirements are cut to the ground. More time-consuming is the Manual harvest. Its advantage is that only the ripe grapes are harvested (or the rotten ones are picked) in several passes at intervals. In Germany, hand harvesting is even required by law for wines of higher predicate levels, and the use of machines is not possible on steep slopes anyway.

After the grapes have been cut from the vine, they are brought to the winery quickly and, if possible, without damage. The size of the collection containers plays a significant role in whether the berries remain intact, as the weight of the grapes below can cause some of their skins to burst. Sometimes the grapes are cooled during transport to the winery in order to keep the flavours fresh.

Additional selection is sometimes carried out at the winery: unusable grapes are thrown away and/or rotten and diseased berries are cut out of the bunches.

Preparation for pressing

Firstly, the grapes are destemmedthe individual berries are freed from the stems and combs, the grape skeleton (rape). However, this is often omitted in order to give the wine more structure and tannin later on.

The berries are then lightly crushed to burst the skins so that the escaping juice can release the colouring and aromatic substances from the skins. Depending on the quality of the grapes and the intended processing time, the resulting mash - the mixture of juice, pulp, skins and seeds - is usually sulphurised at this point at the latest sulphurisedto prevent premature, wild fermentation or oxidation; if necessary, the mash is also cooled. The longer the mash is left to stand, the more intense the colour and aroma of the wine will be later on. As a rule, for rosé wines a Maceration time of a few hours is sufficient for rosé wines. Sometimes no maceration time is required at all, but it can also be up to three days. The winemaker decides when to press the mash and ferment the must.

Through the addition of Enzymes the aroma and colour yield can be further increased if necessary. The enzymes also ensure that the mash is easier to press: The juice emerges better from the berries and because the pressing pressure can be kept lower as a result, fewer tannins and bitter substances are extracted.

Alternatively, after crushing, the juice that has already run out can be separated (Juice extraction). This has less colouring and tannin than the juice that is produced later. The remaining mash is then processed into red wine, the extracted light red or pink-coloured must is fermented into rosé wine (pressing is not necessary).

Pressing

For the actual pressing process (the Pressing) there are several technologies. What they all have in common is that mechanical pressure is exerted on the mash, separating the juice from the solids. These then remain behind as pomace.

A basic distinction is made between vertical and horizontal presses; specific examples are tree or basket presses, screw presses, screw presses, screw presses, tube presses and pneumatic presses, which allow particularly fine regulation of the pressure.

Preparation for fermentation

After pressing, the must - the liquid obtained from pressing - is sulphurised again, if necessary, to prevent uncontrolled fermentation or oxidation, and then clarified. Clarification is carried out either by simply leaving the must to stand for a while so that the lees can settle to the bottom of the tank, or by biochemical and/or physical processes such as the addition of enzymes, filtration or centrifugation. Flotation is a common pre-clarification process: the must is impregnated with air or nitrogen under pressure and then depressurised again. The resulting fine gas bubbles draw the lees upwards in the tank so that the clear juice can simply be drawn off at the bottom.

To correct any off-tones and "adjust" the colourings correctly, the following can be added Activated charcoal can be used.

Using several physical processes, the must can be concentrated can be concentrated:

• With Reverse osmosiswater is removed from the must so that the relative proportion of the remaining ingredients(extract) increases. The must is placed in a chamber that is separated from a chamber containing water by a semi-permeable membrane. Increasing the pressure in the must chamber causes water molecules to migrate from the must chamber into the water chamber.
• During vacuum distillation, water is also removed from the must so that the relative proportion of the remaining ingredients (extract) increases. The process utilises the fact that the boiling point of water falls at low pressure. At a pressure of 0.03 bar, water in the must boils (i.e. vaporises) at a temperature of around 25°C. The resulting vapour condenses on cooled surfaces.
• The freeze concentration (cryoextraction) follows a similar principle to ice wine production: The must is slowly cooled below 0°C until pure ice crystals form from water and the remaining ingredients concentrate. The ice crystals are then separated from the residual liquid.

If the sugar content of the must is not sufficient for successful or desired fermentation, the must can be chaptalised, i.e. enriched with unfermented or fermented must or with sweet reserve in order to increase the alcohol or residual sugar content. Chaptalisation is prohibited for Prädikat wines in Germany.

Fermentation

During fermentation, yeasts convert the sugar from the grapes into alcohol and carbon dioxide, producing heat in the process. Yeasts are already present in the must in their natural form if they have not been killed by some of the measures described above.

If these natural yeasts are used to ferment the must, this is known as Spontaneous fermentation. However, this type of fermentation involves uncertainties because the natural yeasts may not be strong enough to complete fermentation or may produce undesirable chemical compounds that can affect the flavour of the wine or even be harmful to health. For this reason, natural yeasts are often killed by sterilising the must so that fermentation can then be carried out in a controlled manner using pure yeasts.

Pureyeasts have certain properties that are known in advance because they have been specially bred for this purpose. This allows them to be specifically selected and used to ferment the must. The aromatic character of the wine can also be influenced to a large extent with appropriately bred yeasts (keyword: secondary aromas). The addition of fermentation aids and yeast nutrient salts can support the work of the pure yeasts.

Temperature is an important factor in fermentation. Traditionally, the fermentation temperature was more or less self-regulating and depended on the cellar temperature. In modern cellars, the fermentation tanks can be cooled and the fermentation temperature actively controlled: the lower the temperature, the slower the fermentation process(cold fermentation). The size of the fermentation tanks also has an effect on the fermentation temperature: the smaller the tanks, the lower the fermentation temperature. The fermentation temperature and the associated fermentation time have a major influence on the style of the wine.

The yeasts generally work until either the sugar present (or added) in the grapes is completely converted into alcohol or the alcohol content becomes so high that the yeasts stop working. They then become sluggish and die, as they cannot survive in an excessively alcoholic environment. Among the pure yeasts, however, there are particularly efficient types that can easily reach 16 per cent by volume.

If the winemaker wants to produce a residual sweet wine, he can stop the fermentation prematurely. This can be done by cooling or by adding sulphur. A third option is to leave the wine to ferment fully and then add sweet reserve to subsequently increase the sugar content of the wine. The sweet reserve is unfermented (i.e. sweet) grape must that has been sterilised to prevent unwanted fermentation.

Ageing

In most cases, the wine is matured after fermentation in stainless steel tanks or in large or small wooden barrels. Other types of ageing are concrete tanks or - rarely - amphorae (although fermentation usually takes place in the amphora and ageing is predominantly oxidative ).

Ageing in stainless steel tanks produces reductive, fresh and fruity wines. Ageing in large wooden barrels leads to smoother, fuller-bodied wines, as the constant minimal air supply through the wooden walls causes micro-oxidation, which also makes the wine more durable. The small wooden barrel (Barrique) also has the property of releasing toasty and smoky wood flavours and additional tannins into the wine, making it spicier and more complex.

Instead of putting the wine into the wood, it is now also possible to put the wood into the wine: Especially in the New World, a wine with wood flavours may have been aged in a stainless steel tank, but has been given Oak chips oak chips have been added. Although this results in the characteristic flavour, the wine must be given the smoothness of ageing in wooden barrels in another way using suitable treatment methods. The advantage for producers: The use of wood chips is faster and cheaper than ageing in barrique barrels; in addition, the wood influence can be better dosed this way and the amount of wood required is significantly less than for the production of a barrel.

When wines are matured in wooden barrels (especially barriques), they often undergo malolactic fermentation (malolactic fermentation). This is often also known as malolactic fermentation but this process is not carried out by yeasts, but by lactic acid bacteria. These convert the strong malic acid into the milder lactic acid, making the wine smoother and rounder. The BSA can also be actively initiated by the targeted addition of lactic acid bacteria if it does not occur naturally.

Fining and stabilisation

After fermentation or at the latest after the end of the ageing period, the young wine is fined, i.e. it is freed from undesirable substances. These are primarily lees (yeast residues etc.) and compounds that can lead to turbidity or impair the flavour after bottling. These suspended solids are bound with the help of additives that attract them due to an opposing electrical charge. These additives range from animal protein(egg white, casein, gelatine, fish bladder) to chemical fining agents such as bentonite, silica sol, kaolin clay or activated carbon as well as copper sulphate and blood lye salt.

For further Stabilisationgum arabic can be used for further stabilisation.

Wines that are particularly high in acidity can be deacidified can be deacidified by adding calcium or potassium carbonate, which causes tartaric acid to precipitate as salt crystals (tartrate), or by undergoing malolactic fermentation. The crystalline salts of tartaric acid are also known colloquially as tartar. They are odourless and tasteless and completely harmless to health, but in order to precipitate them for aesthetic reasons before bottling, the wine can also be cooled for several days to around freezing point; this process is known as cold stabilisation. The addition of metatartaric acid (produced by esterification of tartaric acid) can prevent the formation of tartaric acid for several months after bottling.

The bound suspended matter, precipitated crystals and residues of the added fining agents are removed after completion of the measures by Racking and subsequent filtration and/or centrifugation.

After fining and stabilisation, the young wine is usually sulphurised again to kill microorganisms and prevent oxidation.

Ascorbic acid (vitamin C) can be added to the wine before bottling to make it last longer. To give young, fruity white wines, which are intended for quick consumption, an extra freshness, carbon dioxide can be added artificially before bottling.

Blending

Blending or cuvetting takes place with the vast majority of wines. This involves not only combining different grape varieties, but also bringing together different origins, sites, tanks and/or barrels in the case of single-varietal wines. As a rule, it is not the grapes or the must that are blended, but only the fully matured young wines. After assemblage (another synonym for blending), the finished wine is left to mature in the cellar for a certain amount of time to harmonise.

Incidentally, in Germany and many other countries, even if a specific grape variety, origin or vintage is stated on the label, up to 15 per cent may contain wines from other grape varieties, sites or vintages without this having to be indicated.

To be very clear once again: rosé wine is not made by blending white wine and red wine! The blending of white and red wine as well as the blending of white and red grape must is prohibited throughout the EU. Only the blending of white and red grapes before processing is permitted. (Exceptions are sometimes made for sparkling wine )

In Germany, there are some special types of rosé:

• Weißherbst is a rosé quality wine that has only been made from a single grape variety.
• Rotling is a regional speciality made from a blend of red and white grapes.
• Schillerwein is a Rotling from the Württemberg wine-growing region.
• Badisch-Rotgold is a Rotling from the Baden wine-growing region, produced by blending Pinot Noir and Pinot Gris.

Bottling

After final filtration and final sulphurisation - which are not necessary if the wine is ready for bottling directly after stabilisation, which includes both measures - the wine is bottled. Sterility is particularly important here in order to prevent impurities that could lead to secondary fermentation in the bottle, for example.

For this reason, the wine is usually bottled under protective gas(nitrogen or carbon dioxide). Sometimes hot bottling is also used, in which the wine is heated to 55°C during filling to kill germs. However, this process can affect the flavour.