Common Elements in Winemaking and Maturation Flashcards
What are the two ends approach on winemaking ?
Control each part of the winemaking process.
- Winemaking is tailored with a particular stylistic goal and techniques are choosen to achieve this goal
Hands-off approach
Overall the wine is produced with as little human intervention as possible, avoiding additions including cultured yeasts and sulfur dioxide, and process taht add or take away from the wine
Name the constituent parts of grapes and their role
Seeds and stems
- contain tannins
- Seed contain high levels of bitter oil
- stems only available when hand harvested
Skins
- skin and area just beneath contains high concentration of flavour compound
- signature varietal character
- tannins, and colour compounds (higher in red rapes)
Pulp
- Highest component is water
- second is sugar
- Acids (tartaric and malic)
tannins
- large number of chemical coumpoumds are classed as tannin
- At véraison, they are bitter but lower as the grapes ripen.
- Oak contribue some tannins.
What is the role of oxygen throughout winemaking and maturation ?
Gas that react with grape juice and mamy other coponents.
The chemical reactions, referred to as oxidation can be positive or negative
Describe the role of oxygen in winemaking
- Oxygen is a threat for wine dominated by primary fruit
How to avoid oxygen contact ?
- Antioxidant such as sulfur dioxide
- Grapes are picked at night when its cooler and the chemical reactions are slower
- Grapes are kept chilled until they reach the winery
- Filling airtight winery equipment with carbon dioxide or nitrogen (known as anaerobic winemaking)
Some may say it makes bland and unintersting styles since oxyen develop complexity, but it’s a question of style.
Describe the role of oxygen in maturation
- Wine that were protected from oxygen during winemaking will rarely have any contact during maturation. They are stored in inert airtight tanks or vats that are kept full, of stainless steel or ciment with epoxy resin
- Other can be stored in wooden vessels, so small amounts of oxygen can make it throught the oak to react with wine.This can soften tannins and gives more complexity (primary to tertiary)
Red wines become paler and gain hint of brown, white wines become deeper and gain hint of orange
To much exposure can be damaging for fruit flavour and smell, and said to be oxidised. Bacteria will use oxygen to change the wine into vinegar
Which factors contribute to the amount of oxidation in barrel maturation ?
- The size of the barrel : small vessels have greater oxidatate effect than large vessels. Rarely kept in barrique for longer than 2 years
- If the barrel is not completely full. Techcnique used for Oloroso Sherry for example.
What is the role of Sulfur Dioxide in winemaking and maturation ?
- Acts as antioxidant and antiseptic
- Used to protect freshly harvested grapes and levels are adjusted throughout the process.
- Upper levels of SO2 are controlled by law
- Can cause allergic reactions, even at low levels.
- Although SO2 is produced naturally in fermentation, it is preferrable to keep it low
- Can make wine seem harsh and lacking in fruit.
- Some wont use SO2 at all.
What are the two effect of SO2 ?
Antioxidant effect
- protects grape juice and wine from effects of oxidation
- in doing so, it loses the ability to have protective effet and becomes a “bound”
- Level of So2 therefore need constant monitoring
Antiseptic effect
- SO2 is toxic to many strains of yeast and bacteria
- Yeast involved in alcoholic fermentation is able to tolerate levels of So2 that are toxic to other species.
What is the purpose of Oak vessels in winemaking and maturation ?
- Allows small level of oxidation , allowing tertiary aromas to develop
- allow extraction of tannin and** flavours **(vanilla, toast, smoke, cloves)
- Oak tannins give more structure to red and white, increasing the textural complexity
- Hygiene is a challenge, difficult to keep free of yeasts, bacteria, moulds and can taint the wine
- Oak vessels differ in characteristics,different types are used to enhance the complexity of final wine
What are the factors to consider when chosing oak barrels ?
- Species and origin of oak
- Size
- Production
- Age
Describe species and origin of oak
- Different species of oak have different characteristics
- Same species of oak an show different characteristics depending on where it is grown.
-Often either European Oak or American oak
European oak has broadly similar characteristics around EU, but some forest, especially in France, are considered the finest.
Explain size of oak barrels
Small vessels (barrels) such as
- 225-litre barrique
- 228-litre pièce,
have greater effect because more of the wine is in contact with the surface
larger vessels can reach sizes in excess of 2000 litres
Explain the production of oak barrels
The way a barrel is made has a vital influence on how it will affect the wine
Toasting of the barrel : heating the staves so they can be bent into shape
transforms tannins and flavour compounds in the oak, giving notes of toast, smoke and spices
Temperature and lenght of heat exposure (level of toasting), affects the flavours
Expain the influence of the age of barrels
Effect of toasting diminishes each time the barrel is used
By the time its on its fourth usage, it imparts little flavour or tannin
Flavours of new oak are not desirable for all wines.
What are the Oak Alternatives
- Small plank of oak (staves) or oak chips can be inserted during fermentation or maturation in inert winery vessels
- Impart oak aromas and tannins at a lower price
- oxidative effect of barrel ageing can be replicated by dding small, controlled quantities of oxygen to wine vessel
Premium wines are not normally made using these techniques.
Explain Stainless steel vessel
- most modern winery vessels
- Easy to keep clean and made in any shape and size
- incorporate temperature control mechanisms (sleeves on the outise or internal coils through which cold or hot liquit is circulated)
Explain concrete vessels
Usually lined with epoxy resin, which is inert and waterproof
Commonly used before stainless steel
Less easy to clean and maintain than stainles steel
Thick concret shells help regulate temperature during fermentation and maturation without the need of temperature control equipment.
What are the general steps of grape processing ?
- Grape reception
- Destemming and cruching
- Pressing
Explain grape reception
receive their first dose of SO2 as they arrive at winery
grapes for premium wine are checked on sorting table to eliminate unripe or rotten grapes
Explain destemming and crushing
Optional process
Destemming
-Machine harvested grapes arrive without stems
- Usually done in a machine that can subsequently crush the grapes
Crushing
- breaks the skins of the grapes and liberates a quanity juice (free run juice)
- should avoid to damage the seed to not relase bitter oils and tannins
Explain pressing
Separates the liquid and solid constituents of the grape
White wine: before the start of fermentation
Red wine: typically after fermentation
Seeds should remain undamaged, and moder technique are designed to achieve gentle pressing
Traditionally: wine presses were vertical, using a plate that was raised or lowered by lever. Now automated, and particularly used in Champagne
Pneumatic presses are more recent, and consist of inflatable rubber tupe within a perforated horizontal stainless steel cylinder. Apply presser over a large area. Grapes can be kept in closed tanks
Winemakers can decide to separate the liquid into different pressings, called fractions and treat them individually.
The winemaker can separate the liquid into different pressings. What are theses liquids called ?
Fractions
When can adjustments can be done to the wine ?
Before, duringg of after fermentation
are subject to regulation in the EU
What is another word to refer to grape juice ?
Must
How can you adjust sugar and alcohol in wine ?
In cooler climate, they may be insufficient narual sugar to give a satisfacotry level of alcohol
Enrichment
- increasing sugar in the juice by adding Rectified Concentrated Grape Must (RCGM). a colourless, odourless, syrupy liquid,
- Before or during fermentation
- This raise the level of alcohol in the wine because more sugar is available
- Forbidden in many parts of the world and is stricly controlled
- Chaptalisation - When sugar from sources other than grapes is added
- Can give better wine, or produce hard and thin waine because there are not enough flavours for the artificial alcohol level.
Remove water from the juice
- Roncentrate sugars and lead to higher alcohol
- Concentrate everything else such as tannins, acids, flavours, faults
- Reduces the volum of juice and less wine is sold.
Remove alcohol from the wine after fermentation
- modern machinery can do it