White and Sweet Winemaking

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:

1. Antiseptic (kills microorganisms)
2. Antioxidant (binds with oxygen)

Question 5

What are 4 commonly practiced must adjustment techniques?

Answer 5

1. Acidification
2. Deacidification
3. Adding RCGM
4. Removing water

Question 6

What does RCGM do when added to grape must (before or during ferementation)?

Answer 6

Raises alcohol in final wine because more sugar is made available for yeasts to turn into alcohol (p.47)

When added AFTER fermentation (p.58), it is used to add a little sweetness, typically to high-volume inexpensive white wines

Question 7

What happens when water is removed as a must adjustment technique?

Answer 7

Sugars are concentrated - which can lead to higher alcohol in final wine - as are tannins, acids, flavor compounds (and any faults, too)

Question 8

Which acid is typically used to acidify a wine?

Answer 8

Tartaric acid

Note that tartaric acid can be used for all colors of wine, not just white wine

Question 9

How is a wine deacidified?

Answer 9

By adding an alkali (an acid neutralizer).

Question 10

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

Answer 10

Acidification

Question 11

What is the difference between enrichment and chaptalisation?

Answer 11

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 12

Why do most winemakers avoid skin contact on their white wines

Answer 12

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

Question 13

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

Answer 13

Because skin contact increases flavor intensity and texture.

Question 14

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

Answer 14

Usually only for a few hours.

Question 15

When are grapes for white wines pressed?

Answer 15

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

Question 16

What 3 main techniques can a winemaker use to clarify the must of a white wine?

Answer 16

1. Sedimentation;
2. Fining;
3. Filtration.

Question 17

What are the two methods of filtration?

Answer 17

1. Depth filtration
2. Surface filtration

Question 18

What is sterile filtration?

Answer 18

When a wine has gone through surface filtration with a filter with pores so small that the filters remove yeast and bacteria.

Question 19

Describe what happens during surface filtration.

Answer 19

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 20

Describe what happens during depth filtration.

Answer 20

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

This type of filtration can handle very cloudy wines

Question 21

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

Answer 21

Unpleasant aromas can form from microbiological issues and fermentation may stop.

Question 22

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

Answer 22

Some winemakers believe that having a small amount of grape solids in a fermenting must will make the resulting wine less prone to oxidation; additionally, they feel these solids will contribute complex flavors and a more pleasing texture to the final wine.

Question 23

What is the most commonly used yeast strain in winemaking?

Why is it preferred?

Answer 23

Saccharomyces cerevisiae

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

Question 24

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

Answer 24

1. Glucose
2. Fructose

Question 25

What aspects of winemaking will determine the speed of fermentation?

Answer 25

* Type and quantity of yeasts; * Nutrient content in the must; * Concentration of sugars in the must; * Temperature (warmer temperatures mean faster fermentations); * How much SO₂ is used (too much slows fermentation).

Question 26

What is the optimum fermentation temperature for white wine?

Answer 26

Between **12°C - 22°C** (54°F - 72°F)

Question 27

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

Answer 27

1. Yeasts may go dormant, but they can be woken up with an increase of heat; 2. Low fermentation temperatures may result in "pear drop" or pear candy aromas and may prevent a grape's true varietal aromas from developing.

Question 28

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

Answer 28

1. Yeasts may die; 2. Hot fermentation temperatures will sometimes create unappealing aromas, and there is a risk that the classic varietal character will be lost in the process.

Question 29

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

Answer 29

* Steel tanks * Oak barrels * Concrete

Question 30

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

Answer 30

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

Question 31

What are the advantages of fermenting in oak barrels?

Answer 31

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

Question 32

Give 3 reasons that will cause a fermentation to stop.

Answer 32

* All available sugar in the must is consumed; * Yeasts run out of nutrients to metabolize; * Temperatures exceed 35ºC (95ºF)

Question 33

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

Answer 33

* **Yeast nutrient deficiencies** in the must, which can lead to stuck fermentations or off-odors; * **Carbon dioxide poisoning**.

Question 34

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

Answer 34

* What vessel to use (oak, stainless steel, etc.) * Whether to blend or not; * Whether to lees age or not; * Whether to allow, actively encourage, or completely block MLC; * Whether to fine or filter the wine, and how much.

Question 35

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

Answer 35

Blending helps the winemaker: * improve consistency, texture, or flavor; * enhance balance; * create wines of a particular or desired style.

Question 36

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

Answer 36

Oak aging is known to add flavors of vanilla, toast, clove, dill, nutmeg, coconut, butterscotch, anise, and smoke.

Question 37

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

Answer 37

The use of oak staves or oak chips. ## Footnote *The oak flavors will be less well integrated into the final wine as oak barrels do more than just add oak flavors, which is why this cheaper method is never used for premium white wines.*

Question 38

What is RCGM?

Answer 38

Rectified Concentrated Grape Must ## Footnote *This important component is used to adjust the sweetness level of a wine without impacting other elements (e.g. acidity or color).*

Question 39

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

Answer 39

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

Question 40

What is malolactic conversion?

Answer 40

Malolactic conversion is a conversion of [tarter, less chemically stable malic acid (the same acid in an under-ripe apple) into softer, creamier, and more stable lactic acid (the same acid in milk or yogurt)](https://www.youtube.com/watch?v=kGaLsljAmz4).

Question 41

What are some notable effects of malolactic conversion?

Answer 41

* Lowers overall acidity; * Creates the aroma of movie theater popcorn butter or melted butter (a compound called diacetyl) * Creates a little CO₂

Question 42

What are some ways to **prevent** malolactic conversion?

Answer 42

* Adding SO₂ after primary fermentation completes; * Storing the wine at cool temperatures; * Sterile filtration.

Question 43

What are some ways to **encourage** malolactic conversion?

Answer 43

* Not adding SO₂ or keeping levels very low; * Warm storage temperatures.

Question 44

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

Answer 44

**Chardonnay** and **Viognier**

Question 45

What's the difference between fining and filtering?

Answer 45

_Fining removes the small stuff you can't see_ - all the unstable, microscopic things in a wine (proteins, phenolic substances, etc.). If these things aren't removed prior to bottling they can clump together later and make the wine appear hazy. To remove these microscopic things, a fining agent is added that bonds with these constituents causing visible clumps to form (which can then be removed by filtering). _Filtering removes the big stuff you can see_ - all the large clumps (e.g. seeds, grape skins, pebbles, spiders) and smaller things like gross and fine lees.

Question 46

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

Answer 46

1. Tartrates 2. Microbiological 3. Oxygen

Question 47

How does a winemaker remove tartrate crystals?

Answer 47

**By bringing down the wine's temperature to 0ºC (32ºF) or colder for 1-2 weeks**. The crystals will precipitate out of the wine (they're about the size of raw sugar crystals) and the winemaker filters them out.

Question 48

What kinds of wine are susceptible to microbiological instability? What kinds of wine are not easily susceptible to microbes?

Answer 48

_Susceptible_ * wines that haven't gone through MLC * wines with low or moderate alcohol * wines low in acid * wines with some residual sugar _Not susceptible_ * wines high in alcohol * wines high in acid * wines that have gone through MLC

Question 49

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

Answer 49

Brown ## Footnote *Wine is made out of grapes, which are a fruit - and most fruits will turn brown if you leave them exposed to oxygen too long (e.g. leaving an apple or avocado uncovered on your kitchen counter).*

Question 50

Name 7 ways sweet wines can be made.

Answer 50

1. Stopping the fermentation 2. Adding a Sweetening Component 3. Concentrating Grape Sugars 4. Noble rot 5. Drying grapes on the vine 6. Drying grapes after picking 7. Freezing grapes on the vine

Question 51

Name 3 ways of making a sweet wine by stopping the fermentation.

Answer 51

1. Fortification (e.g. Port) 2. Adding a high dose of SO2 3. Chilling the fermenting wine

Question 52

What does it mean to 'fortify' a wine?

Answer 52

Adding a grape spirit to fermenting must which stops fermentation while sugar is still present ## Footnote This kills the yeast and no further fermentation is possible

Question 53

When sweet wines are made using the techniques of adding a high dose of SO2 or chilling the wine, why are they filtered?

Answer 53

To remove any remaining yeasts ## Footnote So they don't referment in the bottle

Question 54

What is Süssreserve?

Answer 54

Unfermented grape juice ## Footnote Made by filtering grape juice before fermentation starts or by adding SO2

Question 55

What is RCGM?

Answer 55

Rectified Concentrated Grape Must

Question 56

How are RCGM and Süssreserve used to make sweet wines?

Answer 56

They are used to make off-dry to medium-sweet wine, usually to inexpensive wines

Question 57

Name the fungus that causes Noble rot.

Answer 57

Botrytis cinerea

Question 58

Sauternes and Tokaji are both made using ___ ___.

Answer 58

Botrytis cinerea ## Footnote Or Noble rot

Question 59

# True or False: Is Botrytis cinerea the same fungus that causes grey rot?

Answer 59

True ## Footnote In order for Botrytis to form, specific conditions must be present

Question 60

What are the specific conditions under which Botrytis cinerea forms?

Answer 60

1. Grapes must be fully ripe before the development of the rot 2. Grapes must be grown in a region that provides humid, misty mornings followed by sunny, dry afternoons ## Footnote Damp conditions in the morning allow rot to develop on the grapes. The fungus punctures the grape skin with microscopic filaments, leaving tiny holes in the skin. The warm, sunny afternoons slow the development of the rot and cause water to evaporate from the grape, concentrating its acids, flavors and sugars.

Question 61

What are the flavors wines made from Noble rot have?

Answer 61

* Honey * Apricot * Citrus zest * Dried fruits

Question 62

In a region where Noble rot can live, what happens if conditions are too damp?

Answer 62

The fungus will develop too rapidly and cause grey rot ## Footnote Grey rot splits the berries, encouraging infections

Question 63

In sweet wine production, what is the term often used when referring to drying grapes on the vine?

Answer 63

Passerillage

Question 64

Describe passerillage.

Answer 64

* Once grapes reach full sugar ripeness they begin to dehydrate and turn into raisins on the vine, increasing sugar concentration in the juice * Warm, dry autums are needed for passerillage to happen or grey rot can develop

Question 65

What are the flavor characteristics of a sweet wine made using passerillage?

Answer 65

* Dried fruits * Tropical fruits ## Footnote Wines made using passerillage are sometimes labeled as Late Harvest

Question 66

The Italian term 'passito' is used when a sweet wine is made using this method.

Answer 66

Drying the grapes after picking ## Footnote Passito wines typically have a raisiny quality

Question 67

Describe what happens to grapes when they are frozen on the vine to make sweet wine.

Answer 67

* Water in the grape pulp turns to ice * When the grapes are picked and pressed, this ice remains in the press and the sugar content of the resulting juice is increased

Question 68

Freezing grapes on the vine is a sweet winemaking technique used for ___ from Germany and ___ from Canada.

Answer 68

* **Eiswein** from Germany * **Icewine** from Canada

Question 69

When sweet wines are made by grape sugar concentration techniques, the alcoholic fermentation stops naturally when the yeasts have converted as much sugar into alcohol as they can. Because yeasts struggle to survive in very sugary environments, at what ABV can this happen?

Answer 69

7% ## Footnote Trockenbeerenauslesen are classic examples of this style