Wine Making And Maturation Flashcards
Step of grapes in winemaking
After harvest, the grapes are processed and prepare for alcoholic fermentation, at which point yeast convert the sugars in the grape juice to alcohol.
What is the role of seeds and stems in winemaking?
Seeds and stems both contain tannins. Seeds also contain high levels of bitter oils. The stems are only available to the winemaker of grapes that are hand harvested.
What is the role of the skins in winemaking?
A grape skin is the area immediately beneath contained a high concentration of flavour compounds, which gives each grape its signature varietal character. The skins also contain tannins and colour compounds. The amount of tannins and colour in black grapes is significantly higher than in white grapes.
What is the role of the pulp in winemaking?
Water is by far the largest single component in grape’s pulp and consequently in the wine as well. Sugar is the second largest in grape’s pulp and is of vital importance: the yeast will be used to make alcohol. Acids are also found in the pulp. The most abundant acid is tartaric acid followed by malic acid, and these grape acids are present in the finish of the wine.
Tannins in winemaking/ maturation?
A large number of chemical compounds are classed as tannins. At véraison they taste very bitter and astringent and, as the grapes ripen, the level of bitterness and astringency falls. Note that oak can also contribute some tannins to both red and white wines.
Why it’s best to pick the grapes at night?
it’s cooler and the effect of oxygen is reduced because chemical reactions occur more slowly at lower temperature. The grapes are kept chilled until they reach the winery.
What is referred as protective or anaerobic winemaking?
Filling airtight winery equipment with either carbon dioxide or nitrogen before they are used for grape processing or winemaking.
Is the wine protected from oxygen during winemaking benefit from contact with oxygen during maturation?
No it doesn’t, the wines are stored in inert airtight tanks or vats that are kept completely full. These vessels are either made from stainless steel or from cement lined with exposy resin.
What is wine mature aerobically?
It’s wine matured in contact with oxygen, stored in wooden vessels normally made of oak. Oak may be watertight but not airtight. Small amont of oxygen can make it through the oak to react with the wine. Help to soften the tannins in red wines also gives more complexity to the flavour; primary fruit flavour gradually fade and tertiary characters starts to develop, such as earth and leather.
Does small vessel barriques 225 Litres have a greater oxidative effect than larger vessels?
Yes, they present a larger surface area of wood to the wine. But wines are rarely kept in barriques for longer than 2 years. Wines kept in larger oak vessels may be matured for longer.
What Is the result of too much exposure to oxygen in wine?
For most wines it can be damaging. The resulting wine can lose much of its fresh and smell stale(oxidized). In extreme case bacteria will use oxygen to change the wine into vinegar.
What is the use of sulfur dioxide?
Sulfur dioxide(SO2), is almost used universally in wine making . Acts as an antioxidant and antiseptic. Can be used to protect freshly harvested grapes and levels are adjusted throughout the winemaking process. SO2 is strictly controlled by law because it can be toxic. Some is produced naturally in fermentation. Most winemakers agree to keep the SO2 as low as possible. A very small number of winemakers refuse to use SO2.
Antioxidant effect of SO2?
Protecting the grape juice and wine from the effects of oxidation. In that case the SO2 it is Know as ‘bound’ which loses the ability to have any further protection. Needs constant monitoring to make sure the wine remains protected.
Antiseptic effects in SO2?
Can be toxic for yeast and bacteria, which causes unwanted flavour. Fortunately the principal yeast is able to tolerate levels of SO2.
Why wine can be ruined tainted wood?
Hygiene is a challenge when using oak it’s difficult to keep wooden vessels free of yeast, bacteria and moulds.
Origin of oak ?
European or American. European; France, Hungary, Russia or elsewhere.
Some forests, especially in France are considered to produce the finest oak.
What flavours result from toasting oak barrels?
Transform the tannins and and flavour component, give notes of toast, smoke and spices.
Is the flavour of new oak always desirable?
No, some producers choose not to use new oak barrels in order to have more subtle flavours.
What are the other alternatives for oak aromas and adding tannins?
Staves or oak chips can be insert during fermentation and maturation. Lower cost and yet not premium wines are not normally made using these techniques.
What are inert winery vessels made of?
Most are made of stainless, steel and concrete. Wildly used for fermentation.
Why using stainless steel?
Most modern winery are made of stainless steel; easy to keep clean, can be made in any shape and size. Can also incorporate temperature control mechanism to control the wine or juice temperature.
Why winemaker use concrete vessels?
Thick concrete shells help to regulate the temperature during fermentation and maturation without the need to use expansive temperature control equipment. Lined with epoxy resin provides waterproof barrier.
How does grape reception works?
Grapes usually arrived at the winery with their first dose of SO2. Grapes designed for premium wine will be checked on a sorting table to eliminate unripe or rotten grapes. ( rarely possible in high volume production)
What’s the destemming and crushing process?
- both optional, machine harvested grapes arrive without stems. Even the hand harvested ones are most often removed by winemakers.
- crushing breaks the skin of the grape and liberate a quantity of juice known as free run, should avoid damaging the seeds. If the seed is damaged bitter oils and tannins can be released.( can result to astringent and bitter wine)
