D9: Harvest Flashcards
How was the date of the harvest traditionally chosen?
- readiness measured by potential alcohol levels (e.g. Chablis AOC required min 9.5% potential alcohol)
How is the date of harvest chosen now?
determined on:
- aroma and tannin ripeness
- viticulture
- warmer climates
What is the issue with rain around the harvest?
- constant threat
- need to decide whether to harvest under-ripe grapes or risk rain damage which can dilute grape juice or split skins leading to grey rot and loss of harvest
What is the main way a grower measures ripeness?
SUGAR LEVELS
- measured by handheld refractometer
- harvested between 19 and 25 Brix
- converts to 11 - 15% ABV
AROMA and TANNINS
- determined by taste
What are the three other ways a grower can measure ripeness?
TITRATION
- calculates acid levels (finds out amount of a substance in a solution by gradually adding measured amounts of another substance that reacts in a known way)
pH
- pH of juice read using pH meter
VISIBLE OR NEAR INFRARED SPECTROSCOPY
- high tech
- latter gives multiple readings for sugar, acidity and other compounds
*tasting grapes still the main method used though!
HARVESTING DATES FOR SPECIFIC WINE STYLES
Loire Valley Chenin Blanc
- harvested over 4-6 weeks
- early = sparkling
- mid = dry and off dry
- late = botrytis or late-harvest
HARVESTING DATES FOR SPECIFIC WINE STYLES
California Zinfandel
- early to mid Aug = white zinfandel
- September = red
- selection is key as can have ripe and unripe grapes in the same bunch
HARVESTING DATES FOR SPECIFIC WINE STYLES
Wines with residual sugar
- botrytised wine = several passes in the vineyard
- Eiswein = temps below minus 8
HARVESTING DATES FOR SPECIFIC WINE STYLES
Extended ‘hang time’
- can make wine overly alcoholic and unbalanced
- critics and consumers love them
Machine Harvesting
- default for inexpensive, mid-priced and large scale productions
- vineyards set up from outset to facilitate machinery
Previously associated with lower quality wines but taking steps to improve quality by:
- selecting out by hand-harvesting undesirable fruit before machine begins
- using B0W-ROD SHAKING MACHINE as it is gentler and more selective than older machines
- using latest machinery which includes optical sorting, crushing white grapes and adding SO2
- more rigorous sorting upon arrival at the winery
What are the advantages (5) and disadvantages (7) of machine harvesting?
ADVANTAGE
- faster, cheaper (up to 1/3 price of hand-harvesting)
- avoids labour issues
- can harvest at night - up to 15 degrees cooler so grapes in better condition, reducing microbial spoilage and oxidation
- cooler grapes preserve fruit aromas and saves refrigeration costs
- timing of harvest can wait until desired ripeness and can then do it quickly
DISADVANTAGE
- less gentle than hand-harvesting - still risk of grape skins being damaged as they are shaken off stems. Also need to consider style of wine being made in case need whole bunches, or want to avoid oxidation, or extraction of phenolic compounds
- not practical for small vineyards
- not practical if have different varieties ripening at different times in same vineyard
- can’t use on steep slopes
- need good operator
- if don’t own one then can struggle with competition at harvest
- major investment
What is hand harvesting?
- teams of harvesters removing whole bunches from vines by cutting stems of each bunch with secateurs
- preferred
What are the advantages (3) and disadvantages (3) for hand-harvesting
ADVANTAGES
- highly selective - can remove diseased, underripe grapes etc
- deal with steep slopes, irregular rows, mixed plantings
- can avoid fruit spoilage by using small stackable crates
DISADVANTAGES
- expensive
- requires reliable and trained workforce
- carried out in daylight so difficult to avoid high temps
- favoured by prem producers but cost and scarcity of labour is making some rethink
What are the five things which REQUIRE hand harvesting?
- premium sparkling wine which need whole bunches for pressing (e.g. champagne)
- those doing carbonic or semi-carbonic maceration (e.g. Beaujolais)
- selective harvesting (e.g. making trockenbeernauslese)
- very steep slopes (e.g. Douro)
- bush vines
