Ch. 9 Harvest Flashcards
What is the rule of thumb regarding harvest timing?
Grapes ripened 100 days after the beginning of flowering
Define potential alcohol and give examples of regulations in AOC’s
Potential alcohol is the amount of alcohol that would be created by fermenting all the sugar in grape must into alcohol.
Cool regions - once potential alcohol reached 9.5-11% abv, grapes could be harvested
- Petit Chablis AOC 9.5% abc min; Chablis 10% min, Bourgogne Blanc 10.5% min
What has recently impacted the the context for decisions about harvest?
- Generally warmer climate, so easier to ripen grapes in cool climates
- Better viticulture, enabling vine to ripen grapes fully
- Focus on aroma and tannin ripeness over sugar ripeness
How does rain affect the harvest period?
Rain will impact timing decisions if it is forecast around harvest -> risk of harvesting too early or leave grape on vine
Rain can dilute grape juice or risk splitting skins, which leads to risk of grey rot
What factors impact harvest date?
- Sugar levels
- Aroma + tannin ripeness
- Acid levels
- Weather hazards (rain)
- Law (alcohol regulations)
- Logistics (worker availabiilty)
- Style (elegant, jammy etc)
What do grape growers measure for when deciding the optimum time of harvesting?
- Sugar levels - dry still wines harvested b/t 19-25 Brix (which equals 11-15% abv)
- Acidity levels - titration to calculate acid levels (adding a reactant to measure amount of substance in a solution); pH meter to calc pH
- Aroma + tannin ripeness - determined by taste
- high tech means available, but tasting remains one of most imp ways of deciding when to harvest
Give examples of how a wine’s style might impact harvesting date.
- Loire Valley - harvesting Chenin over 4-6 weeks depending on wine style - early for sparkling, mid for dry and off dry, late for botrytis or late harvest
- California - harvest Zin in early to mid August for White Zin, or in Sept for red wine. Also if a consistently high quality is required, careful selection because Zin tends to have ripe and unripe fruit on same vine. Also hot areas. - include shrivelled grapes?
- For wines with RS, harvest dates are very imp since later harvest dates concentrate sugars more. Botrytised wines need hand harvest, several passes, careful selection for most affected. Icewine requires specific temps for picking (eblow 18F/8C for Canadian Icewine)
- Extended hang times can make wines overly alcoholic and unbalanced - style preference, what is rewarded by critics (full-bodied Cabs)
Machine harvesting is most common for inexpensive to mid-priced wines and larger-scale production. Typically equated with acceptable to good level quality wines.
What steps can be taken to improve quality today?
- selecting out undesirable fruit by hand before harvesting by machine (adds labor/time cost)
- using a bow-rod shaking machine which is gentler than beating vines and can be more selective (can be more expensive)
- invest in latest machines, which have optical sorting devices, can crush white grapes and add SO2 to limit oxidation (expensive)
- rigorous sorting on arrival in winery, includinr removal of MOG and unripe or rotten grapes (labor/time cost)
What are the advantages of machine harvesting?
- Significantly faster and cheaper (if this has been part of vineyard design)
- More reliable and available than casual workers
- Grapes can be harvested at night and kept cooler (up to 59F/15C cooler), which minimizes bacterial spoilage and oxidation –> imp to preserve freshness of fruity white wines (like SB) and save cost of refrigeration
- More flexible than assembling and deploying pickers - timing can move around depending on ripeness and then happen immediately
How can vineyards prepare for machine harvest?
- Design: even row spacing, a turning space at the end of the rows, on flat land or on land w small, regular gradient (avoid slipping machinery)
- Low-density, widely-spaced, trellised
- avoid waterlogging, good drainage
What are the disadvantages of machine- harvesting?
- Less gentle than hand-harvesting –> can’t keep whole bunches intact, grapes are shaken off stems (can lead to splitting, some release of juice)
- so not effective for whole bunch fermentation, delicate whites where oxidation or early extraction is bad)
- Not cost effective for small vineyards
- Not suitable for growers with several different varieties ripening at diff times in same plot
- Not suitable for steep slopes w limited access (Mosel, N. Rhone, Douro)
- Need skilled operator
- Competition for rental
- Major investment if purchasing
What does hand-harvesting require?
Usually best for making premium wines because of labor/time cost invovled.
Teams of harvesters remove the whole grape bunches from the vines by cutting the stem of each bunch with secateurs.
What are the advantages of hand-harvesting?
- Highly selective at bunch by bunch level to remove diseased, under or extra ripe fruit
- Acceptable for steeper slopes, irregular rows, and mixed plantings
- Avoid crushing of grapes and release of juice and therefore risk of oxidation and bacterial spoilage - if handled with care, put in small, stackable crates
What are the disadvantages of hand-harvesting?
- More expensive than machine harvesting in medium to large vineyards
- Requires availability of reliable work force and supervision
- Because of labor it is most easily carrided out in daylight- hard to avoid high temps. Raises likelihood of spoilage by microbes or oxidation –> some hand harvest at night and provide pickers w torches
- Labor shortage, scarcity of labor + adv of machine harvesting are making some producers reconsider their options
