All About Grapes
The grape is the main ingredient of any wine. However, the species grown is different to the seedless grape often found in the supermarket or local convenience store. The species of grape grown for wine production is known as ‘vitis vinifera’ and are typically smaller and have thicker skins.
Although temperate areas with adequate rainfall are required for wine growing, In order to produce the best harvests, vines should be stressed. If there is too much rainfall the vines become lazy and they don’t produce enough good quality fruit. The climate that vines are grown ultimately influences the overall taste of the wine. In areas where temperatures are cooler, wine will inherently have a lower alcohol content and higher natural acidity.
The characteristics of the soil itself also influence the final taste of the wine. Certain minerals give the grapes added nutrients whilst growing. Also, some soils drain the water away from the vines during times of high rainfall so that the vines do not become saturated. In essence each vineyard has its own distinctive ‘terroir’ that ultimately determines the wine produced. ‘Terroir’ is a French term used to describe each vineyards individual personality attributed to its location, climate and soil type.
The fermentation process occurs in all wine production. In order to start this process either cultured yeasts can be added to the grape juices or wild yeasts, that naturally occur, can be developed. The yeast interacts with the sugar, converting this to alcohol.
How White Wine is Made
When making white wine, the grapes are almost always crushed and de-stemmed before being transferred to the press, where they are squeezed, separating the juice from the pips. The skins, stems and pips are removed because they often contain butter tannins which are undesirable in white wines, although often sought after in reds. Sulphur dioxide is often added to the grape mixture during the process to prevent fermentation from occurring too early, the wine changing colour and creating extremely strong flavours.
The fermentation process for white wine can take between a few days to a month and often occurs in cool temperatures in order to preserve a “freshness” of aroma and flavour. After fermentation whites can be bottled straight away, making them relatively cheap to produce. Some white wines are fermented throughout in oak barrels in a process called “barrel fermentation”, which can take between 6 and 12 months before being transferred to a tank for final filtration and fining. Other wines are fermented in stainless steel tanks. Also, some varieties can undergo a second fermentation process call malolactic fermentation whereby the acidic malic acid is converted into lactic acid. This technique is most often used in Chardonnay and Semillon varietals “softening” the high acidity of the grape and producing a more neutral, creamy flavour.
Filtration and fining are the last processes that sometimes occur before bottling. Here, impurities within the wine are filtered away and also further additives are added. Some more traditional wine produces believe that filtration and fining remove some of the wines key aromas and flavours and do not believe the process to be worthwhile.
How Red Wine is Made
When making red wine the skins of the grape, and sometimes the stems too, are incorporated into the fermentation process. In fact, the juice of a red grape is as clear as the white grape, it is the grapes´ skins that create the red colour and unmistakable flavour. The mixture of grape skins and juice is often transferred to open top wooden or stainless steel tanks after crushing for the fermentation process. During fermentation, the build up of carbon dioxide causes the skins of the grapes to float to the surface. However, in order to achieve the desired flavour contained within the skins, the mixture must be mixed.
In the olden days this process was completed by labourers, whom pushed the skins back into the mixture with their legs. Nowadays this practise has been stopped, due to health and safety legislation. A less hazardous process, called pigeage, is still used in some traditional practices where a long broom-like device is pushes the skins manually in the fermenting mixture. A more common, and modern practice called “pumping over” automates this process. Whichever method is employed, the process occurs several times a day until the fermentation process is finished.
Most red wines undergo a fermentation process of between six months to two years in oak barrels of varying ages, makes and sizes. At the end of the process the bottom of the fermentation tank contains the skins, pips and whole grapes. This juice is full of flavour and is sometimes used for blending during later processes.
How Sparkling Wine is Made
The fizz in sparkling wine is produced due to saturated carbon dioxide bubbles within the pressurised bottle. The cheapest method of creating sparkling wine is to add carbon dioxide directly into the wine mixture by a process called “carbonation”. This “transfer method” is used to produce a large volume of low and medium priced sparkling wine. After this carbonation, a second fermentation process takes place in an enclosed pressurised tank, as not to lose the carbon dioxide within the wine mixture. Once this is completed the wine is blended or sweetened as required before being bottled under pressure.
A more traditional method of developing sparkling wine, the “methode traditionelle” generally produces the best quality sparkling wines and also the most expensive. Here, a second fermentation process actually occurs within the pressurised bottle itself, with the resulting carbon dioxide produced being trapped within the seal.
The waste associated with the fermentation process form a deposit at the bottom of the bottle which must be removed to achieve the desired clean, transparent look. This process is completed by riddling (or remuage) whereby the bottles are placed in wooden racks and each day are turned by an eighth of a full circle until positioned upside-down. The unwanted sediment is then trapped within the neck of the bottle and then frozen.
During “disgorgement” the seals of the bottle are removed and the pressure of the carbon dioxide within the bottle forces the sediment out. The wine is then filled with a small amount of sugary wine (liqueur d´expedition) to counter the high acidity due to this second fermentation process. Corks are then inserted and the wine is rested for another period before transportation and sale.
Article written by Kevin Allen, author and founder of [http://www.essentialfinewines.com/]
[http://www.essentialfinewines.com/] is an impartial wine information site, allowing lovers of wine to find their favourites. Visitors can discuss their experiences and give opinions on different wine matters. The site also has extensive sections covering premixed wine cases and wine gifts.
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