Harvest Flashcards
Harvest
Known as picking, generally marks the end of grape ripening. Timing of harvest can have a significant impact on the levels and nature of various compounds within the grapes and therefore can have an influence on the style and quality of the finished wine.
Choosing the date of harvest
Traditionally 100 days after the beginning of flowering
In many European regions readiness for harvest has been measure by potential alcohol levels:
- Petit Chablis 9.5%-11%
- Chablis 10%
- Bourgogne blanc 10.5%
Nowadays, the decisions about harvesting dates has changed due to:
- Generally warmer weather, making it easier to ripen grapes in cooler regions
- Better viticulture, enabling the vine to ripen grapes fully
- Focus on aroma and tannin ripeness, which is sometimes considered more important than optimum sugar ripeness
There is one overriding factor:
The trait of rain in the harvest period! If rain is forecasted, grape growers may have to choose between harvesting under ripe grapes or risk leaving grapes on the vine in the hope that the weather will improve.
Rain in the last days before harvest can lead to diluting the juice or, worst case, splitting of the skins due to rapid expansion, with the treat of grey rot and loss of some or all the harvest
Measuring ripeness
Grape growers will measure various components in the grapes to decide the optimum time of harvesting for the style of wine they are aiming for.
Sugar:
Measured by a handheld refractometer. Most dry still wines are harvested between 19 and 25 Brix –> 11-15%abv
Aroma and tannin ripeness is usually determined by taste –> experience
Give examples of harvesting dates for specific wine styles (Loire Chenin Blanc, Californian Zin, RS wines)
Loire Chenin Blanc is harvested over a period of 4-6 weeks:
- Early for sparkling wines
- Mid harvest for dry and off-dry styles
- Late for botrytis or late harvest styles
Californian Zinfandel:
- Early to mid August for White Zinfandel
- September for red wines
- Growers must decide whether or not to include shriveled grapes
Wines wit RS:
- Harvesting late to concentrate the sugars in the grape
- Botrytis, hand harvest, several passes
- Eiswien/Icewine can only be picked when temperatures reach below certain levels (Icewine -8)
Machine harvesting
Has become the default option for inexpensive to mid-priced wine and for larger-scale production (SA excluded, still very low labor costs).
Machine harvesting used to be equated with only acceptable to good level quality wines. However, steps can be taken to improve quality (at a range of different costs):
- Selection out undesirable fruit by hand before harvesting by machine
- Using a bow-rod shining machine, gentler, and can be more selective
- Investing in the very lates machines that have options for optical sorting devices on them, which can crush white grapes and add SO2 in the machine itself
- Rigorous sorting on arrival in the winery, including the removal of MOG (matter other than grapes) and urn pen and rotten grapes
Advantages of machine harvesting
- Faster and cheaper in large vineyards, if the vineyard has been designed with this in mind
- Avoids issues of the lack of availability of, and possible unreliability among workers
- Grapes can be harvested at night and be kept up to 15 degrees cooler (than picking during the day) and therefore in better condition. Thin can reduce microbial spoilage and oxidation
- For white, fruity wines, starting the winemaking with cool fruit preserve the intensity of fruity aromas. And also helps to save refrigerator costs
- Timing of harvest can wait until the desired level of ripeness has been achieved and then carried out quickly. By comparison, assembling and developing a group of pickers may be less flexible and slower
Disadvantages of machine harvesting
- Less gentle than hand harvesting and involves grapes shaken of the stems (rupture of the skin / releasing juice), rather than keeping the bunches in tact. This is a consideration when making some styles of whine (whole bunch fermented)
- Not economic or practical for small-scale vineyards. Rental or ownership of a machine is not cost effective for smaller wineries
- May be unsuitable for 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 operator
- There may be competition for the renal of machinery at the best moment for harvest
- Purchasing a harvester is a major investment
Hand harvesting
Some growers, especially those aiming to make premium wines, prefer to harvest by hand.
On the other hand. Some one styles require hand-harvesting. Including:
- Premium sparkling wines made where whole Bunche are required for whole bunch pressing (Champagne, and most bottle fermented sparklings around the world)
- Wines form Beaujolais and other wines that will be made by carbonic or semi-carbonic maceration require whole bunches for the process
- Making a style of wine that requires selective picking grapes, for example botrytis affected bunches (TBA)
- When grapes are on steep slopes (Douro)
- Buch vines, no trellis to hold the vines
Advantages of hand harvesting
- Pickers can be highly selective at a bunch by bunch level and to remove any diseased, unwanted fruit (underipe/overripe)
- Pickers can deal with supper slopes, irregular rows and mixed planting in the same vineyard
- If handled with care and put in small, stackable crates (max 10-15 kg), crushing of the grapes and release of the juice (prone to oxidation and microbial spoilage) can be avoided
Disadvantages of hand harvesting
- It’s more expensive than machine harvesting in medium to large vineyards
- Requires the availability of a reliable work force and their training and supervision to ensure that they work to the required standard
- Harvest must be carried out at daylight hours and may not be able to avoid high temperatures; and raises the change of grapes being spoiled by microbes or oxidation
