9.1 Choosing the Date of Harvest

Question 1

What is harvest?

Answer 1

• aka picking the grapes

- Generally marks the end of grape ripening

Question 2

What was the traditional rule of thumb for harvesting?

Answer 2

Grapes ripen 100 days after the beginning of flowering

Question 3

Traditionally, how was readiness for harvesting measured?

Answer 3

• Potential alcohol levels (The amount of alcohol that would be created by fermenting all the sugar in grape must into alcohol)

Question 4

More recently, how is readiness for harvesting measured?

Answer 4

• A generally warmer climate: making it easier to ripen grapes in cooler regions
• Better viticulture: enabling the vine to ripen grapes fully
• A focus on aroma and tannin ripeness, which is sometimes considered as more important than optimum sugar ripeness.

Question 5

What can be an overriding factor in determining the harvest date? Why?

Answer 5

• Threat of rain in the harvest period
• If rain is forecast, grape growers may have to choose between:
  1. harvesting under-ripe fruit
  2. risk leaving grapes on the vine in the hope that the weather will improve.
• Rain in the last days before harvest can lead to
  1. diluting of the juice
  2. splitting of the skins due to rapid expansion (grey rot)

Question 6

How is ripeness measured?

Answer 6

1. Sugar levels – The amount of sugar in ripening grapes is easily measured by a handheld refractometer. Most dry still wines are harvested between 19° and 25° Brix (one of the scales used to measure the amount of sugar in the juice), which will convert into 11–15% abv.
2. Aroma and tannin ripeness (taste!)

Question 7

How is the amount of sugar in ripening grapes measured? What scale is used?

Answer 7

• A handheld refractometer

- Brix (one of the scales used to measure the amount of sugar in the juice)

Question 8

At what sugar level are most dry, still wines harvested? To what abv range will that convert?

Answer 8

• between 19° and 25° Brix

- 11–15% abv

Question 9

What is used to calculate acid levels?

Answer 9

• A titration: method of finding out the amount of a substance in a solution by gradually adding measured amounts of another substance that reacts in a known way
• pH of the juice can be read by a pH meter

Question 10

Describe harvest for Loire Chenin Blanc.

Answer 10

When?
- Harvested over a period of 4–6 weeks
Why?
- Depends on the style of wine to be made:
– early for sparkling wine
– mid-harvest for dry and off-dry styles
– late for botrytis or late harvest styles

Question 11

Describe harvest for California Zinfandel.

Answer 11

When?
- Early to mid-August for White Zinfandel
- September for red wine
Concerns.
- Zinfandel tends to have unripe and ripe fruit on the same vine, care has to be taken with selection if a consistently high quality is required.
- Include shrivelled grapes or not.

Question 12

Why are harvest dates extremely influential for wines that have residual sugar?

Answer 12

• Some harvested late to concentrate the sugars in the grapes
• Some need hand-harvesting over several passes through the vineyard to select the most botrytised grapes at that time
• Some grapes can only be picked when temperatures reach below certain levels (Icewine, Eiswein)

Question 13

What is hang-time? Why is it controversial?

Answer 13

• The amount of time grapes are left on the vine after ripening.
• Con: Overly alcoholic and unbalanced wines lacking in natural acidity and having extra-ripe fruit character.
• Pro: Critics reward these wines with high scores; consumers like them