L3C07 Common Elements In Winemaking And Maturation Flashcards
What is the next stage in winemaking after harvest?
The grapes are processed and prepared for alcoholic fermentation
On a basic level, what is alcoholic fermentation?
Yeast converts sugars in the grape to alcohol
What is the next basic stage of winemaking after alcoholic fermentation?
The wine needs to be stored prior to packaging and sale
Broadly speaking, what are natural wines?
Wines made with minimal intervention
Describe the seeds and stems of the grape
Both contain tannins
Seeds contain high levels of bitter oils
How are stems made available to the winemaker
By hand harvesting
Why is the grape skin important to the winemaker?
The skin and the area immediately underneath, contain high levels of flavour compounds (containing the grape’s signature character)
It contains tannins
It contains colour compounds
A large number of chemical compounds are classed as…
Tannin
Describe tannins at Véraison
How does this change?
They taste very bitter and astringent
As grapes ripen, bitterness and astringency fall
What is the Bloom of a grape?
The waxy surface that covers the skin of a grape
It contains yeast that can be used for fermentation
List the three major constituents of a grape’s pulp
Water
Sugar
Acid
What is the largest constituent of a grape’s pulp?
Water
What is the second largest constituent of a grape’s pulp?
Sugar
In order, what are the most abundant acids in a grape’s pulp?
Tartaric acid
Malic acid
What can oxygen react with during winemaking and maturation?
Grape juice
Many of the component parts of a wine
What is oxidation?
Oxygen reacting with any component part of a wine
What is the biggest threat to a winemaker wanting their wine to be dominated by primary fruit characteristics?
Oxidation
How is the risk of oxidation broadly avoided by a winemaker?
Use of antioxidants such as Sulfur Dioxide
Keeping oxygen contact to a minimum
Why might grapes be picked at night?
It is cooler and the effect of oxygen is reduced because chemical reactions occur more slowly at lower temperatures
How are grapes kept away from oxygen once they reach the winery? What is this process called?
By filling airtight winery equipment with carbon dioxide or nitrogen before they are used for grape processing or winemaking
Protective/anaerobic winemaking
What is the argument against anaerobic winemaking?
Some argue that the resultant wines may be bland or uninteresting and that a higher level of oxygen contact helps to develop complexity and character
…rarely if ever benefit from oxygen contact during maturation
Wines that have been protected from oxygen during winemaking
How are anaerobically made wines stored?
In inert airtight vessels which are kept completely full
The vats are made from stainless steel or cement lined with epoxy-resin
How are aerobically made wines usually stored?
In wooden vessels that are normally made of oak
Oak is…but it is not…
Watertight
Airtight
How does the mild oxygen permeability of oak help a wine?
It can help to soften tannins in red wines
Gives more flavour complexity
What happens to flavours in wine during deliberate oxidation/maturation?
Primary fruit flavours gradually fade
Tertiary characters start to develop, such as leather and earth
Other than flavour, how may a wine change as a result of oxidation?
Red wines become paler and gain a hint of brown
White wines become deeper in colour and gain a hint of orange
What two main factors influence the amount of deliberate oxidation a wine receives?
Size of vessel
Length of time stored in it
How does barrel size affect the amount of oxidation a wine receives? Why?
Smaller barrels have a greater oxidative effect
They present a proportionately larger surface area of wood to the wine
How large is a barrique?
225L
Wines are rarely kept in barriques for longer than…
Two years
How may the effect of barrel oxidation be further enhanced?
If the container is not completely full
Name three wines which are matured in barrels which are not completely full
Oloroso Sherry
Rutherglen Muscat
Tawny Port
What characters do wines which are deliberately aged take on?
Caramel, toffee and nuts
What may happen to a wine if it’s exposed to too much oxygen?
It can lose much of its fruit flavour and smell stale
What can happen to over-oxidised wine in extreme cases?
Bacteria can use the oxygen to turn the wine to vinegar
What are the main uses of Sulfur Dioxide in a winery?
Antioxidant effects
Antiseptic effects
Which element in winemaking can be toxic? How is this prevented?
Sulfur Dioxide
It is regulated by law
Which major element in winemaking can cause allergic reactions, even at low levels?
Sulfur Dioxide
Why might a quality-conscious winemaker want to keep SO2 levels as low as possible?
It can make wines seem harsh and lacking in fruit
When used as an antioxidant, why must SO2 levels be constantly monitored?
By protecting wine from oxidation, SO2 becomes ‘bound’ and can have no further protective use
Why is SO2 effective as an antioxidant?
It is toxic to the many strains of yeast and bacteria that can cause unwanted flavours in wine
Is SO2 toxic to the principal fermentative yeast involved in winemaking?
No, this strain is resistant to certain levels of SO2
The majority of wooden vessels used in winemaking are made of…
Oak
Other than oxygen, what can oak ageing give to a wine?
Tannins
Flavours
What does oak-tannin give to a wine?
Structure/textural complexity
What kind of flavours can oak give to a wine?
Toast
Vanilla
Smoke
Cloves
What is a particular challenge when using oak for maturation? Why?
Hygiene
It is particularly difficult to keep wooden vessels free of yeasts, bacteria and moulds
Why may a winemaker use different types of vessel during maturation?
As oak vessels differ widely in their characteristics
To enhance complexity in their wines
What are the four major factors to consider when choosing oak for maturation?
Species and origin of oak
Size
Production of oak barrels
Age
Describe why species of oak is an important factor in flavour characteristics
Flavour can change, even within a species of oak
…oak has broadly similar characteristics no matter which country it’s from
European
Where is some of the finest oak considered to be from?
Some forests in France
What is a 228L barrel known as?
Pièce
How large can wine maturation vessels get?
More than 2000L
What is one of the most important procedures when it comes to how a barrel affects the flavour of a wine?
Toasting
How are the barrel’s staves prepared so they can be bent into shape?
They are heated
What secondary effects does the heating of a barrel’s staves have?
It transforms the tannins and the flavour compounds in oak
What flavours are newly produced by a barrel once it is toasted?
Sweet spice
Toast
What does ‘level of toasting’ refer to in the making of a barrel?
The temperature and length of heat exposure
What affects the flavours a barrel can give to a wine?
The level of toasting
What happens each time a barrel is used?
The effect of toasting diminishes
Why might a winemaker not use new oak?
In order to make a wine with subtler oak flavours
How else may oak flavours and tannins be added to a wine, other than using barrels? What is the advantage of doing this?
By using oak staves or oak chips
It’s cheaper
How may the oxidative effects of barrel ageing be replicated?
By adding small, controlled quantities of oxygen to the wine vessel
What is an inert wine vessel?
It does not add flavour to the wine or allow oxidation
What are the majority of inert winery vessels made from?
Stainless steel or concrete
What can inert winery vessels be used for?
Fermentation
Temporary storage of wine after it is finished
What are most modern winery vessels made from?
Stainless steel
List the advantages of stainless steel as a winery vessel
Easy to keep clean
Can be made into any shape and size
Can incorporate temperature control mechanisms
What are the two main types of temperature control mechanisms?
Sleeves on the outside of the vessels
Internal coils through which cold or hot liquid can be circulated
What are concrete vessels usually lined with? What does this do?
Epoxy resin
It’s inert and provides a waterproof barrier
What was commonly used before stainless steel vessels?
Concrete vessels
What are the disadvantages of concrete vessels over stainless steel?
They can be less easy to clean and maintain
Why might some winemakers prefer concrete vessels?
The thick concrete shells help to regulate temperature during fermentation and maturation without the need for expensive equipment
Name a wine vessel which is not steel or concrete…
Glass bottles
When do grapes usually use their first dose of SO2?
When they arrive at the winery
Besides receiving SO2, what else may happen to wine grapes during reception?
They may be individually checked and sorted for unripe and rotten grapes
What is the next possible stage after grape reception?
Destemming and crushing
What does crushing do?
It breaks the skin of the grapes and liberates a quantity of juice
What is the liquid product of crushing called?
Free run juice
What is the danger when crushing grapes?
If the seeds are crushed, they will release bitter oils and tannin
What does pressing do?
It separates the liquid and solid constituents of the grape
Why are modern pressing techniques designed to be gentle?
As with crushing, to avoid crushing the seeds
What is the traditional design of grape presses?
They were all vertical
How does a vertical press work? What is a traditional vertical press called?
The pressure on the grapes comes from above, using a screw or lever
A basket press
Name a wine producing region which is still particularly known for its vertical presses
Champagne