Fundamentals Unit Part 3 - White Wine Production

Question 1

What is the first step in white wine production?

Answer 1

Grapes are harevested and pressed.

Question 2

What is whole cluster-pressing and why is it regarded as producing better wine

Answer 2

It is gentler and produces a cleaner must which requires less to be done to it as it is made. It can also reduce exposure to O2 preserving aromas.

Question 3

Why is SO2 added by some producers?

Answer 3

It acts as an antioxidant and antiseptic protecting the wine on its journey.

Question 4

What is “debourbage”?

Answer 4

It is “juice settling” ie the must before fermentation. This is normally chilled and left to settle for 12-24 hours. Sediments and particles fall to the bottom of the vessel.

Question 5

Can acid or sugar be added to the must prior to fermentation?

Answer 5

Only when permitted by law. Both cannot be added to the same vat of must.

Question 6

Why might acidification take place?

Answer 6

If the wine will lack freshness then acid can be added in the form of a powder.

Question 7

What is chaptalisation?

Answer 7

Chaptalisation is the adding of sugar to the pre-fermented must. It can only be done to increase abv and cannot be used to sweeten a wine. It must alll be fermented ie NO RS

Question 8

When will chaptalisation be appropriate?

Answer 8

1. If the grape juice lacks sufficient sugars to provide the minimum abv required by the AOC law;
2. To increase the abv to render the wine more stable;
3. to balance the wine.

Question 9

What is the temperature range for white wines?

Answer 9

12C to 22C (text says between 14-20C)

Question 10

What technology contributes to fermentation management?

Answer 10

Temperature controlled fermentation (mostly in Stainless Steel tanks) allows for the long cool fermentation which can preserve the aromatics and fruit character.

Question 11

What is alcoholic fermentation?

Answer 11

At the correct temperature, yeast will consume the sugars in the juice and produce alcohol and CO2. In some cases eg sweet wines, some residual sugar will remain.

Question 12

What is a “stuck fermentation”?

Answer 12

It is one which has stopped accidentally and the yeast are unable to convert all of the sugars to alcohol. It can be particularly due to the higher ripeness of grapes nowadays which challenge the yeast. The wine will not be fermented to dry.

Question 13

When might a fermentation be interrupted by the vigneron?

Answer 13

1. Wine style - desired level of sweetness is achieved;
2. Fortification - neutral grape alcohol is added to stop the fermentation. It kills the yeast and leaves RS.

Question 14

What is ‘Maceration Pelliculaire”?

Answer 14

It is the technique of leaving the white grapes to macerate on the skin for a few hours after crushing. This allows more aromatics. Used normally on the aromatic varieties.

Question 15

What are the two common types of yeast used in winemaking?

Answer 15

Ambient (wild) yeast and Cultured yeast.

Question 16

What are the characteristics of cultured yeasts?

Answer 16

They offer more control over the fermentation process and deliver wine that is varietally clean and correct. They function well at low temperatures, produce low levels of by-products and off-aromas. They ferment more quickly than ambient yeasts.

Question 17

What are the characteristics of ambient/wild/indigenous yeasts?

Answer 17

They ferment more slowly, (months), are less predictable and less efficient in production of alcohol and are more sensitive to it. Wines made from ambient yeast are more prone to vintage variation and can produce off-odours.

Question 18

What is a flavour precursor and what is its relevance in winemaking?

Answer 18

A precursor is a chemcal compound that itself does not have a flavour, but when interacting with another compound releases a flavour. In grapes, the precursors are bound to the grape sugars.

Question 19

How does yeast contribute to flavour?

Answer 19

Each type of yeast has enzymes which release specific precursors from the sugars so they can be smelled and inhaled. As it converts sugars to alcohol, the yeast also releases components which create a signature palette of aromas.

Question 20

How does a winemaker “ferment for flavour”?

Answer 20

Modern cultured yeasts can be used to maximise or minimise specific aromas in the final wine. Yeast cocktails can be used to avoid one-dimensional wines.

Question 21

What is “malaolactic conversion”?

Answer 21

It is a process whereby lactic bacteria convert tart, green malic acid into softer, creamier lactic acids. It can also produce aromas of yogurt, butter, butterscotch, caramel and toffee..

Question 22

When is malolactic conversion not carried out?

Answer 22

On less aromatic varieties, to preserve the fruit character of the wine. This can be done by adding SO2 or cooling the wine.

Question 23

What are lees? What do they do in this state?

Answer 23

Lees are dead yeast cells remaining after fermentation which settle at the bottom of the vessel. They protect the wine from oxidising.

Question 24

What is “sur lie” ageing?

Answer 24

It is the process of leaving the wine to rest on top of the lee. It develops nutty complexity. .

Question 25

What is “autolysis”?

Answer 25

It is the decomposition process of dead yeast cells. As the yeast decompose they release manno-proteins which add a creamy texture to the wine ie mouthfeel.

Question 26

What is “batonnage”

Answer 26

Batonnage is the techniwque of stirring the lees in the vessel to better integrate the flavours of autolysis and malolactic conversion.

Question 27

What is RACK and RETURN?

Answer 27

It is the first layer of “clarification”. The removal of the lees and any other unwanted particulates from the wine.They are RACKED off and SO2 adjusted. The wine is then RETURNED to its clean holding vessel. The process may be repeated several times until the wine ‘falls bright”.

Question 28

Why might SO2 be added after rack and return?

Answer 28

To prevent oxidation and/or malolactic conversion.

Question 29

When might wine be blended?

Answer 29

Before or after ageing, depending on Style, Balance, Consistency or Complexity requirements.

Question 30

Why is a white wine clarified?

Answer 30

Consumers do not want to drink wine which may not be clear and contain some particles. (In general). Clarifying removes any unwanted particulates or other matter.

Question 31

What other clarification methods are used besides rack and return?

Answer 31

Sedimentation, (settling of the lees etc in the vessel);
Centrifuging (Expensive machinery but quick);
Flotation (clumping together of particles on surface over time - slow);
Filtering (sterile and depth)

Question 32

What is sterile filtration?

Answer 32

It is process using a filter that has small enough pores that can remove particles as small as bacteria. The danger is that this can also remove flavour compounds which is not desirable. However microbiological spoiling is removed requiring less SO2.

Question 33

How does fining differ from filtration?

Answer 33

Fining uses the principle of positive and negative charges and the attraction of opposites.

Question 34

Describe fining.

Answer 34

A fining agent is added to the wine which binds with any suspended particulates. These visible clumps are than removed by filtering the wine. It helps to stabilise the wine for a longer period.

Question 35

What are the main fining agents used in wine?

Answer 35

Bentonite (clay) - bonds with proteins;
Gelatin - …tannins;
Egg white - … tannins;
Casein - … tannins

Question 36

Why is wine stabilised?

Answer 36

Tartrates can appear in wine if it is subjected to cold temperatures for a period, eg cellaring, transport. To avoid the unsightly crystals, the wine, in the vat/vessel, is chilled to 0C which makes them appear in the wine. They can then be removed before bottling.

Question 37

Summarise the main steps in white wine making.

Answer 37

1.Harvest and press; 2. SO2 addition (optional); 3. Debourbage (juice settling); 4. Acidification or Chaptalisation (Must adjustment); 5.Fermentation; 6. Malolactic Conversion, Sur Lie ageing, batonnage (optional); 7 Rack and Return (SO2 adj.); 8. Blending (BCCS); 9. Clarifying; 10.Stabilisation.