WINEMAKING | DESCRIBE KEY PROCESSES

Question 1

Oak Vessels

Answer 1

Allow small levels of oxidation

Extra tannin and flavour from oak

Smaller vessels = more of the wine is in contact with the oak

Age = effects of the oak diminish with each use

Question 2

Crushing

Answer 2

Breaks the skins of the grapes and ‘liberates’ free run juice without damaging the seeds.

Question 3

Pneumatic pressing

Answer 3

Inflatable rubber tube within a perforated, horizontal stainless steel cylinder.

Apply pressure over a larger area in a controlled way.

Can be closed to minimise oxygen contact

Question 4

Rectified Concentrated Grape Must (RCGM)

Answer 4

Added to increase sugar levels, in cases of the must weight in the juice being too low, either before or during fermentation.

Raises the alcohol level of final wine.

Question 5

Removing water from juice

Answer 5

To increase sugar levels, in cases of the must weight in the juice being too low, before fermentation.

Raises the alcohol level of final wine.

But concentrates everything (tannin, acid, flavour and faults).

Question 6

Acidification

Answer 6

Addition of tartaric acid in powdered form.

Question 7

Deacidification

Answer 7

Excess acid neutralised by the addition of an alkali.

Question 8

Malolactic Fermentation (MLF)

Answer 8

After alcoholic fermentation.

Lactic acid bacteria convert tart malic grape acid into softer lactic acids.

Softens and reduces acidity + creates buttery flavours.

Encouraged by raising the temperature of a wine and not adding SO2.

Avoided by cool temperatures, adding SO2, or filtering out bacteria.

Question 9

Lees

Answer 9

Yeast die and form a sediment of lees (dead yeast cells and grape fragments).

Dead yeast cells begin to break down and release chemical compounds into the wine.

Gross lees (large particles) fall to the bottom and are ‘racked off’ to prevent unpleasant aromas to develop.

Fine lees (smaller particles) are removed gradually depending on desired flavour.

The longer the wine spends in contact with the dead yeast cells (fine lees) the more intense the bread and biscuit flavours produced + the richer the texture.

Question 10

Sedimentation

Answer 10

Part of the clarification process to produce a perfectly clear wine.

After gross lees have settled the wine is slowly and gently pumped into a different vessel (racking).

Process is repeated (sediment settles, wine is racked).

Relies on gravity but can be sped up by a centrifuge.

Question 11

Fining

Answer 11

Haze/deposits appear in a wine when constituents clump together over time.

Fining speeds this up so that the particles can be removed before bottling.

Involves adding a fining agent that forms bonds with certain wine constituents and causes visible clumps to form.

This is filtered out.

Question 12

Depth Filtration

Answer 12

Physically removes particles from a wine as it is passed through thick layers of material. Solid parts become trapped.

Can be filtered after fermentation and during maturation to remove gross and fine lees quickly.

Also filtered prior to bottling.

Question 13

Surface Filtration (Sterile filtration)

Answer 13

Solid particles are trapped on the surface of the filter as the wine flows through ‘pores’.

Generally used for wines that have already been depth filtered.

Sterile filtration is when ‘pores’. are small enough to trap yeast and bacteria.

Question 14

Tartrate Stability

Answer 14

Tartaric acid forms crystals called tartrates. Harmless and flavourless but can spoil the appearance.

Either: long maturation in cool cellars
or
Chilling the wine down to 0 degrees for a short period, then filtering.

Question 15

Microbiological Stability

Answer 15

Yeast and bacteria can spoil a wine.

Fortified wines - alcohol too high

MLF wines - quite resistant due to alcohol, acidity and lack of nutrients

Non-MLF wines - SO2 and sterile filtered

Question 16

Oxygen Stability

Answer 16

Wine can oxidise and lose fresh fruit aromas.

Minimised by keeping avoiding exposure to oxygen and keeping SO2 levels topped up.

Question 17

Pre-fermentation extraction

Answer 17

Once the fruit has been crushed, the grapes are left to macerate for a period at a low temperatures before fermentation.

Extracts colour and flavour compounds. Tannins are more soluble in alcoholic solutions and are less readily extracted at this point.

Question 18

Temperature during fermentation

Answer 18

Red wine - 20 to 32 degrees

White wine - 12 to 22 degrees

Question 19

Carbonic maceration

Answer 19

Whole uncrushed bunches placed into vats

Vats filled with CO2 to remove all oxygen.

Fermentation starts in the grapes and the grapes split at 2% alcohol.

Split grapes release their juice.

Grapes pressed to separate the skins.

Ambient yeast complete fermentation off the skins.

Question 20

Semi-carbonic maceration

Answer 20

Whole bunches placed in vat

Fruit at the bottom of the tank is crushed by the weight of the fruit above it.

Grapes split and release juice.

Ambient yeast ferment the juice at the bottom of the tank

CO2 forms and blankets the rest of the fruit in the vat

Remaining berries undergo carbonic maceration.

Question 21

Whole bunches with crushed fruit fermentation

Answer 21

Mix whole bunches with crushed fruit in the fermenting vessel.

Whole bunches aren’t blanketed in CO2, but the crushed grapes protects them from oxygen and intracellular fermentation occurs.

Whole bunches crushed as the cap is punched down.

Question 22

Direct pressing

Answer 22

Rose winemaking

Black grapes are crushed and pressed to extract some colour from the skins

Care should be taken not too extract too much tannin

Fermentation takes place off skins in cool fermentation conditions.

Question 23

Short maceration

Answer 23

Rose winemaking

Black grapes are crushed and allowed to macerate to extract flavour and colour (duration depends on required colour and tannin)

Free juice will be drained off the skins and fermented at cool temperature

Question 24

Second alcoholic fermentation

Answer 24

Sparkling - traditional method

Liqueur de tirage is added (wine, sugar, yeast) to the bottle.

Bottle is sealed.

Bottles are stacked horizontally and cool, constant temperatures .

Slow fermentation.

Raises alcohol by 1.2-1.3% abv and CO2 created dissolves into the wine making it sparkling.

Question 25

Yeast Autolysis

Answer 25

Sparkling - traditional method

After second fermentation the yeast dies and forms sediment of lees in the bottle.

Dead yeast cells break down releasing chemical compounds into the wine.

Add bread, biscuit, toasty notes.

Four to five years. After which lees keep the wine fresh.

Question 26

Riddling

Answer 26

Sparkling - traditional method

After maturation the lees sediment is removed by moving the bottle very slowly from horizontal to vertical.

Yeast sediment is dislodged and collects in the neck.

Question 27

Disgorgement

Answer 27

Sparkling - traditional method

Upturned bottle placed into a very cold brine solution to freeze the wine in the neck.

Crown cap removed and the pressure from the dissolved CO2 ejects the frozen wine taking the sediment with it.

Question 28

Liqueur d’expédition

Answer 28

Sparkling - traditional method

Mixture of wine and sugar.

Often known as dosage.

Used to balance the acidity and helps with flavour/ house style.

Question 29

Transfer method

Answer 29

Sparkling

Same as traditional method but at the point of riddling the entire contents of the bottle is disgorged into a sealed tank.

Wine is filtered, Liqueur d’expédition added and wine is rebottled.

Look for ‘bottle-fermented’

Question 30

Asti method

Answer 30

Sparkling

fermentation takes place in pressurised tanks.

Initially CO2 is allowed to escape. Part way through the tank is sealed so CO2 is retained.

Ferment continues until 7% abv.

Fermentation stopped early, by chilling the wine, before all the sugars are fermented.

Wine is filtered to remove the yeast and wine is bottled immediately.