Grape berry

Question 1

What are the parts of a grape berry’s anatomy?

Answer 1

• Epidermis (skin) which produces a thin cuticle layer that is waterproof
• Peripheral pulp: right under skin which containes high proportion of colored pgments tannins and flavors
• Pulp: large cells with thin cell walls containing juice
• Central pulp: surrounding seeds
• Seeds: Embryo and albumen (food for embryo). Contain tannins
• Stems: Bring sugars to berries

Question 2

What are the main constituents of berry juice?

Answer 2

Water (80%)
Sugars and other carbs (20%)
Acids (1%)
Phenolic compounds (.1%)
Mineral salts (potassium) which mask acid effects

Question 3

What sugars are in the berry?

Answer 3

Glucose: easier to ferment
Fructose: more difficult to ferment but present in late harvest wines

Question 4

What other carbs are found in a berry and what do they do?

Answer 4

Pectins
Difficult to extract or clarify grape juice
Can be broken down by enzyme
Gewurz and Viognier high in pectins

Question 5

What are the main acids present in a berry?

Answer 5

Tartaric
Malic
Both organic
(Also citric, ascorbic, acetic)

Question 6

What are anthocyanins?

Answer 6

Pheonlic compound with color under skin

Act antioxidant and preservative. Responsible for red wine color.

Question 7

What are the stages of development in a berry

Answer 7

Herbaceous/vegetative
Veraison
Maturation
Sur-maturation

Question 8

What are phenolic compounds?

Answer 8

Group of chemical compounds that affect a wine’s color, texture, astringency, and bitterness

Question 9

What are catechins and epicatechins?

Answer 9

Smaller phenolic molecules that can taste bitter or waxy

Question 10

What are tannins?

Answer 10

Large phenolic compounds that determine body and astringency. Act as antioxidants and preservatives. Act as precursors to aromatic compounds when wine are aged.

Question 11

What happens during the herbaceous phase? How long is it?

Answer 11

When the green part of the vine is growing (from formation of berry until veraison) - 60 days (small hard green and taste acidic)

Question 12

What is veraison? How long does it last?

Answer 12

Lasts 4-7 days. Marks beginning of berry ripening
Cell layers below the skin become colorless in white varieties and light then dark red in red varieties
Skin is more elastic
Stops photosynthesizing (sugars accumulating next stay in the berry)
Size mostly remains same

Question 13

What happens during the maturation phase? How long does it last?

Answer 13

40-60 days
Grapes increase in sugar and acidity decreases
Berry loses herbaceous flavor gains fruity flavors
Berry softens and gains weight and volume from water
Increase in glucose and fructose
Acidity decreases due to dilution
Increase in phenolic levels
Desirable flavors mostly accumulate later in ripening

Question 14

What is the sur-maturation stage?

Answer 14

When the berries are left on the vine after ripening is complete - over ripe
Fruit loses water and juice is concentrated
Impt for some sweet wines

Question 15

How can maturity be measured?

Answer 15

Physiological maturity - max sugar content and size and the vascular bundles stop functioning
OR
Phenolic maturity - actual maturity, stem and seeds are brown, taste fruit

Question 16

How long from fruit set to harvest, generally?

Answer 16

100-120 days