D1.C9. Harvest Flashcards
What was the traditional rule of thumb for estimating ripeness of the grapes?
Grapes ripen 100 days after the beginning of flowering
Especially in European regions, readiness for harvest has been measured by which factor?
Potential alcohol levels
In cool regions, once potential alcohol has reached to which range, can the grapes could be harvested?
9.5–11% abv
Petit Chablis require a minimum of 9.5%
Chablis requires 10%
Bourgogne Blanc 10.5%.
More recently the context for making decisions about harvesting dates has changed due to:
- A generally warmer climate
- Better viticulture, enabling the vine to ripen grapes fully
- A focus on aroma and tannin ripeness
Name one climatic threat during harvest period
Rain
What are the adverse effects of rain in the last days prior to harvest?
- Dilution of grape juice
- Splitting of the skins with consequent threat of grey rot
Name the criteria for measuring ripeness?
- Sugar levels
- Acidity levels
- Aroma and tannin ripeness
How is the sugar level measured?
Handheld refractometer
Most dry still wines are harvested between what Brix levels?
19° and 25°, which will convert into 11–15% abv
How is acidity measured?
- Titration can be used to calculate acid levels
- pH of the juice can be read by a pH meter
How is aroma and tannin ripeness measured?
By tasting
What is the most important way of deciding, when to harvest?
Tasting the grapes
How does the style of the wine affect the harvest date?
- Chenin Blanc can be harvested over a period of 4-6 weeks
+ Early for sparkling wine
+ Mid-harvest for dry and off-dry styles
+ Late for botrytis or late-harvest styles - Zinfandel
+ In early to mid-August for White Zinfandel
+ In September for red wine - The grapes for botrytised wines often need hand-harvesting over several passes
- For Icewine, grapes can only be picked when temperatures reach below certain levels
(e.g. below -8°C / 18°F for Canadian Icewine)
What are the risks for extended hang time for the grapes?
- Overly alcoholic and unbalanced wines
- Low in natural acidity
- Extra-ripe fruit character.
Machine harvesting has become the default option for which types of producers? Which country is an exception?
- For larger-scale producers, making inexpensive to mid-priced wines
- South Africa (due to availability of labour at a low cost)
How can the quality of the machine harvested grapes be improved?
- Selecting out undesirable fruit by hand before harvesting by machine
- Using a bow-rod shaking machine
- Using latest machines that have options for optical sorting devices
- Rigorous sorting on arrival in the winery, including removal of MOG
What are the advantages of machine-harvesting?
- Faster and cheaper
- Avoids issues of the lack of availability of, and possible unreliability among, casual workers
- Grapes can be harvested at night
+ Reduce microbial spoilage and oxidation
+ Saves the cost of refrigeration - The timing of the harvest can wait until the desired level of ripeness has been achieved and then carried out quickly
What are the disadvantages of machine-harvesting?
- Less gentle
- Not cost-effective for small vineyards
- Unsuitable for grape growers that have several different
varieties ripening at different times in the same plot - Not suitable for vineyards on steep slopes or with limited access
- The quality of the work is only as good as the skills of the operator
- There may be competition for the rental of the machine at the best moment for harvest
- Purchasing a harvester is a major investment
When hand-harvesting is usually preferred?
For producing premium wines
What are the advantages of hand-harvesting?
- Highly selective
- Suitable for steeper slopes, irregular rows and mixed plantings
- If handled with care and put in small, stackable crates (with a maximum weight of 10–15 kilos), the crushing of grapes and the release of juice, which would then be prone tooxidization and to microbial spoilage, can be avoided
What are the disadvantages of hand-harvesting?
- Expensive
- It requires the availability of a reliable work force and their training and supervision to ensure that they work to the required standard
- Harvest is carried out in daylight hours and may not be able to avoid high temperatures
When is hand-harvested required?
- Style
+ Whole bunch pressing (Champagne, Beaujolais)
+ Selective harvesting (Trockenbeerenauslese) - Geography: Douro Valley, Mosel
- Vine training: Bush vines
