Chapter 1 - Wine Composition And Chemistry

Question 1

What are the major components of wine?

Answer 1

Water
Alcohol
Acid
Sugar
Phenolic compounds

Question 2

80-90% of wine

Answer 2

Water

Question 3

10-15% of wine

Answer 3

Alcohol, primarily ethyl alcohol/ethanol

Question 4

What other types of alcohol occur in wine?

Answer 4

Glycerol, methyl alcohol/methanol, and fusel alcohols (fusel oils) or higher alcohols

Question 5

What can result in tears or legs in the glass?

Answer 5

High levels of alcohol or residual sugar

Question 6

How is a wine’s aroma carried to the nose?

Answer 6

Ethanol, a volatile compound, evaporating easily

Question 7

0.5% to 0.75% of wine

Answer 7

Acids

Question 8

Principal acids found in wine

Answer 8

Tartaric 
Malic
Citric
Lactic
Acetic
Succinic

Question 9

Grape acids

Answer 9

Tartaric
Malic
Citric
Succinic

Question 10

Fermentation acids

Answer 10

Lactic
Acetic
Succinic

Question 11

Which acids are found in minute quantities in grapes?

Answer 11

Citric

Succinic

Question 12

What are wine diamonds?

Answer 12

Solid crystals formed from tartaric acid at low temperatures that do not redissolve in wine, lowering the acidity of the wine.

Question 13

What is the strongest acid in wine in terms of pH?

Answer 13

Tartaric

Question 14

What is the flavor profile of Malic acid?

Answer 14

Sharp tasting, green apples

Question 15

What grapes are high in Malic acid?

Answer 15

Underripe and cool-climate grapes

Question 16

What acid may be added to increase the total acidity of a wine?

Answer 16

Citric

Question 17

How is lactic acid produced in wine?

Answer 17

Lactic acid bacteria converts malic acid during malolactic fermentation

Question 18

What is acetic acid?

Answer 18

Found in most types of vinegar, a low level is created during fermentation. It is volatile so it evaporates and joins the aroma, adding complexity to the bouquet, particularly in reds.

Question 19

What is acetobacter?

Answer 19

Harmful (to wine) bacteria that causes a reaction between ethanol and oxygen resulting in higher concentrations of acetic acid possibly making a wine undrinkable.

Question 20

What is succinic acid?

Answer 20

Minor component of grapes, by product of normal fermentation. Sharp, slightly bitter, slightly salty flavor.

Question 21

What is total acidity?

Answer 21

Volume of all acids in a wine

Question 22

What is pH?

Answer 22

Combined chemical strength of the acids present.

Question 23

Typical pH scale of wine

Answer 23

2.9 to 3.9

Question 24

What percent of sugar do grapes contain at harvest?

Answer 24

15-28%

Question 25

What are the main sugars in grapes?

Answer 25

Glucose | Fructose

Question 26

What are the phenolic compounds found in wine?

Answer 26

``` Anthocyanins Flavonols Tannins Vanillin Resveretrol ```

Question 27

What are anthocyanins?

Answer 27

Give red wines their color.

Question 28

How does acidity affect color in red wines?

Answer 28

More acidic wines appear redder, less acidic wines appear bluer

Question 29

What are flavonols?

Answer 29

Yellow pigments found in white wines. Increased by exposure to sunlight. Summer climates will produce more golden wines than cooler/cloudier climates.

Question 30

What are tannins?

Answer 30

Astringent, bitter compounds found in skins, seeds, and stems of grapes and also in oak and oak barrels. They form the structure or backbone of wine and are a natural preservative to protect from oxidation in the aging process. Produce a textural, drying sensation.

Question 31

What is vanillin?

Answer 31

Aromatic compound in oak that imparts a vanilla scent to barrel aged wines.

Question 32

What is resveretrol?

Answer 32

Compound believed to have beneficial health effects in humans.

Question 33

Where are phenolics primarily concentrated?

Answer 33

The skin and seeds of grapes.

Question 34

How is sediment created?

Answer 34

Phenolic compounds, mainly tannins and pigments, polymerize, becoming too heavy to stay suspended in the liquid and drop out of the solution. One of the main results of the aging process.

Question 35

What are aldehydes?

Answer 35

Oxidized alcohols formed when wine is exposed to air.

Question 36

What is acetaldehyde?

Answer 36

Most common aldehyde which is formed by the oxidation of ethanol. Gives fino sherries their distinct aroma.

Question 37

What are esters?

Answer 37

Molecules resulting from the joining of an acid and an alcohol. Largest odiferous compounds in wine.

Question 38

What is ethyl acetate?

Answer 38

Most common ester in wine, the ester of acetic acid and ethanol.

Question 39

What is the effect of ethyl acetate?

Answer 39

In low concentrations, fruity, flowery aroma. | In high concentrations, faulty aromas of nail polish remover, varnish, or glue.

Question 40

Why is sulfur added?

Answer 40

To absorb free oxygen molecules that can harm wine.

Question 41

What is the threshold for "Contains Sulfites" warning labels?

Answer 41

10 parts per million