Vins blancs

Question 1

What color grapes can be used to make white wine?

Answer 1

Predominantly white grapes, but many red/black grapes may also be used.

Question 2

What are some important considerations winemakers have to weigh before processing and fermenting white grapes?

Answer 2

Length of skin contact, if any
Fermentation temperature
Fermentation vessel
Use of lees
Malolactic conversion - whether or not they’ll allow it and to what degree later on

Question 3

What chemical can be used at multiple points during the winemaking process to prevent oxidation and inhibit the growth of microorganisms?

Answer 3

Sulfur dioxide (SO2)

Question 4

What are some of the effects Sulfur dioxide (SO2) has on wine during the winemaking process

Answer 4

SO2 acts as an:

Antiseptic (kills microorganisms)
Antioxidant (binds with oxygen)

Question 5

What are four commonly practiced must adjustment techniques?

Answer 5

Adding RCGM (Rectified Concentrated Grape Must - raises alcohol in final wine because more sugar is made available for yeasts to turn into alcohol)
Removing water (concentrates sugars - which can lead to higher alcohol in final wine - and concentrates tannins, acids, flavor compounds, and any faults, too)
Acidification
Deacidification

Question 6

Which acid is typically used to acidify a wine?

Answer 6

Tartaric acid

Question 7

How is a wine deacidified?

Answer 7

By adding an alkali (an acid neutralizer).

Question 8

What is the most common must adjustment made to white grapes from warm/hot climates?

Answer 8

Acidification

Question 9

What is the difference between enrichment and chaptalisation?

Answer 9

Both are adding sugar before or during fermentation in order to increase the alcohol level in a wine, but which term used depends on the TYPE of sugar used.

Enrichment uses RCGM;
Chaptalisation uses dry, non-grape sugar, e.g. sugar beet.

Question 10

Why do most winemakers avoid skin contact on their white wines

Answer 10

To reduce the risk of oxidation and the extraction of unwanted flavors.

Question 11

Why would some winemakers keep white wine juice in contact with the grape skins?

Answer 11

Because skin contact increases flavor intensity and texture.

Question 12

If a winemaker is doing skin contact for a white wine, how long will the juice stay in contact with the skins?

Answer 12

Usually only for a few hours.

Question 13

When are grapes for white wines pressed?

Answer 13

Before fermentation (ideally, shortly after they’re harvested and brought to the winery).

Question 14

What four techniques can a winemaker use to clarify the must of a white wine?

Answer 14

Settling;
Centrifugation;
Fining;
Filtration.

Question 15

What are the two methods of filtration?

Answer 15

Depth filtration
Surface filtration

Question 16

What is sterile filtration?

Answer 16

A

Surface filters look like very fine sieves, so as wine flows through this filter solid particles are captured on the surface. They can clog easily so generally they’re used AFTER depth filtration.

Question 17

Describe what happens during depth filtration.

Answer 17

Thick filters have wine passed through them to trap solids, such as gross lees

This type of filtration can handle very cloudy wines

Question 18

What can happen to a white wine if the winemaker does not clarify the must adequately?

Answer 18

Unpleasant aromas can form from microbiological issues and fermentation may stop

Question 19

Why do some winemakers choose not to over-clarify their white wine musts?

Answer 19

some winemakers believe that having a small amount of grape solids in a fermenting must will make the resulting wine less prone to oxydation; they also feel these solids will contribute complex flavors and a more pleasant texture.

Question 20

What is the most commonly used yeast strain in winemaking?

Why is it preferred?

Answer 20

SACCHAROMYCES CEREVISIAE. This yeast strain is preferred because of its hardiness against SO2 and elevated levels of alcohol.

Question 21

What are the two sugars found in grapes which are easily converted into alcohol?

Answer 21

GLUCOSE
FRUCTOSE

Question 22

What aspects of winemaking will determine the speed of fermentation?

Answer 22

Type and quantity of yeasts;
Nutrient content in the must:
Concentration of sugars in the must;
Tempearture (warmer temp. mean faster fermentation);
How much SO2 is usedb(too much slows fermentation).

Question 23

What is the optimum fermentation temperature for white wine?

Answer 23

12-22°

Question 24

What may happen if white wines are fermented at too low a temperature?

Answer 24

Yeasts may go dormant, but they can be woken up by an increase of heat;
Pear drop or pear candy aromas
can prevent a grape’s true aromas from developing

Question 25

What may happen if white wines are fermented at too warm a fermentation temperature?

Answer 25

Yeasts may die.
Hot fermentation temperatures will sometimes create unappealing aromas; there is a risk the classical varietal character is lost in th process.

Question 26

What kinds of vessels are commonly used to ferment white wines?

Answer 26

STEEL TANKS
OAK BARRELS
CONCRETE

Question 27

What are the advantages of fermenting white wines in stainless steel?

Answer 27

Stainless steel is inert (non-reactive) which helps maintain varietal character;
Temperature control system are easier to build into stainless steel fermenters than oak or cement.

Question 28

What are the advantages of fermenting in oak barrels?

Answer 28

Oak barrels are known to transfer heat effectively.
Oak barrels will add richer flavors and rounder textures.

Question 29

What will cause a fermentation to cease (aka a stuck fermentation)?

Answer 29

All available sugar in a must is consumed;
Yeast run out of nutriments to metabolize;
Tempeartures exceed 35°.

Question 30

What are some potential complications a winemaker can run into during fermentation?

Answer 30

YEAST NUTRIENT DEFICIENCIES in the must which can lead to stuck fermentations or off-odors;
CARBON DIOXYDE POISONING.

Question 31

What are some important choices winemakers must make post-fermentation in white wine vinification?

Answer 31

• What vessels to use (oak, stainless steel, …)
• whether to blend or not
• whether to age on lees or not
• whether to allow / encourage MLC
• whether to fine or filter the wine, and how much.

Question 32

What are some of the benefits of blending white wines post-fermentation?

Answer 32

• improve consistency, texture or flavor;
  Enhance balance
  Create wine of a particular or desired style.

Question 33

What flavors will aging in new oak add to white wines?

Answer 33

Oak aging adds flavors of vanilla, toast, clove, dill, nutmeg, coconut, butterscotch, anise and smoke.

Question 34

What less-costly methods may be substituted for oak barrels but still add desirable oak flavors to value-priced white wines?

Answer 34

USE OF OAK STAVES OR CHIPS
The oak flavors will be less integrated into the final wine as oak barrels do more than just add oak flavors, which is why cheaper metod is never used for premium white wines.

Question 35

What is RCGM?

Answer 35

RECTIFIED CONCENTRATED GRAPE MUST
This important component is used to adjust the sweetness level of a wine w/o impacting other elements (eg acidity or color)

Question 36

What is lees stirring (aka bâtonnage) and what are its benefits?

Answer 36

Lees stirring, or batonnage, is when the winemaker stirs the lees (dead yeast cells) that fell to the bottom of a fermentation vessel, breaking them open so that they can release amino acids. These acids add more creamy, round and mouth-filling elements resulting in a wine with greater complexity and mouthfeel.

Question 37

What is malolactic conversion?

Answer 37

Conversion or taretr, less chemical stable malic acid into softer, creamier and more stable lactic acid.

Question 38

What are some notable effects of malolactic conversion?

Answer 38

Lowers overall acidity;
Creates the aroma of movie thater popocorn butter or melted butter (diacetyl);
Creates a bit of CO2.

Question 39

What are some ways to prevent malolactic conversion?

Answer 39

Adding SO2 after primary fermentation completes;
SToring the wine at coll temperature;
Sterile filtration.

Question 40

What are some ways to encourage malolactic conversion?

Answer 40

Not adding SO2 or keeping its level very low;
Warm storage temperatures.

Question 41

What white grape varieties are most likely to undergo malolactic conversion?

Answer 41

CHARDONNAY
VIOGNIER

Question 42

What’s the difference between fining and filtering?

Answer 42

Fining removes all small stuff that you can’t see - all the unstable, microscopic things in a wine (proteins, phenolic substances…). If these things are not removed prior to bottling, they can clump together later and make the wine appear hzy. A fining agent is added that bons with these constituents causible visible clumps to form which can then be removed by filtering.
FILTERING removes the big stuff you can see - all the large climps (seeds, grape skins, pebbles…) as well as smaller things like gross and fine lees.

Question 43

Winemakers should ensure their wines are stable in what three areas?

Answer 43

TARTRATES
MICROBIOLOGICAL
OXYGEN

Question 44

How does a winemaker remove tartrate crystals?

Answer 44

Bring the temperature down to 0° or colder for 1-2 weeks.
The crystals precipitate out of the wine (they are the size of raw sugar crystals) and the winemaker filters them out.

Question 45

What kinds of wine are susceptible to microbiological instability?

What kinds of wine are not easily susceptible to microbes?

Answer 45

SUSCEPTIBLE:
- wines that have not been through MLC
- wines with low or moderate alcohol
wines low in acid
wines with some residual sugar.
NOT SUSCPTIBLE:
- wines with alcohol, high in cid, ,
- wines that have been through MLC.

Question 46

What color will a white wine turn if it’s exposed to too much oxygen?

Answer 46

BRAOWN
Most fruits turn to brown if you leave them exposed to oxygen too long.