Vinification Flashcards
Why is SO2 generally added to fermenting must or juice beforehand?
To prevent oxidation and bacterial contamination and to ensure rapid fermentation.
How is volatile acidity (ethyl acetate) created in wine? (Chemical reaction)
small amounts of acetaldehyde present naturally in finished wine is converted to acetic acid, which in turn reacts with alcohol to produce ethyl acetate
What happens when excessive volatile acidity in the wine has led to the wine becoming faulty?
excessive acetic acid has been produced by the activity of acetobacter, the group of bacteria responsible for turning wine to vinegar in the presence of oxygen.
What happens when the amount of nitrogen present in the fermenting must is deficient?
Because yeast require nitrogen to work, low levels of nitrogen in the must leads to the formation of hydrogen sulfide (H2S), a highly volatile compound reminiscent of rotten eggs.
What compounds are produced under reductive conditions in a fermenting must?
sulfides including H2S, mercaptans and other foul-smelling compounds
Below what temperature will most yeasts cease to act? Above what temperature will most die?
Below 50F most yeasts will cease to work
Above 105F yeasts will die.
If whole berries are used in the fermentation, what will occur? What grapes is this method commonly used on?
Will cause partial carbonic maceration.
Pinot Noir and Syrah are common grapes that are fermented in this manner
What does whole-cluster fermentation promote?
Better movement of juice and air through the cap.
What does cold soak aim to achieve? How is it promoted? How long does it typically last? Where was it pioneered and when? What is the most common grape to employ this technique on?
Aims to achieve the extraction of color and tannin prior to fermentation.
It is promoted by allowing must treated with SO2 to macerate under temperatures too cold for yeast to start fermenting, but not cold enough to prevent extraction of color and tannin.
Typically lasts for nearly a week before fermentation
Pioneered in Burgundy in the 1970s
Pinot Noir is the most common grape that this technique is used on.
5-10 degrees C or 40-50 degrees F
When does maceration occur-before, during, or after fermentation?
Can occur at each period.
Cold soak maceration (pre fermentation)
Normal maceration (during)
post-fermentation for tannic styles like Nebbiolo which can last up to a month following the end of fermentation.
What does soutirage refer to? What does it provide for the wine?
soutirage refers to the racking or movement of wine from one vessel to another, providing aeration and clarification as the wine is removed from its lees, or sediment.
What is the French term for fining?
Collage
What are 5 agents commonly used for collage (fining)?
bentonite
casein (a milk protein)
isinglass (material obtained from sturgeon bladders)
gelatin
egg white
What are the two most common species of French oak used?
- Quercus robur
- Quercus petraea
What is the main American oak species?
Quercus Alba
What are the French terms for warming, shaping, and toasting oak staves respectively?
chauffage (warming)
cintrage (shaping)
bousinage (toasting)
What is Prep 500?
Description: Manure from a lactating cow placed inside a cowhorn and buried during winter.
Use: Stimulates soil microbial life and encourage root growth.
Application Method: Applied in spring and fall, preferably within half an hour of sunset, on recently worked soil.
What is Prep 501?
Description: Paste of silica (powdered quartz) and water placed inside a cowhorn and buried during summer.
Use: Encourages photosynthesis and ripening.
Application Method: Applied in late spring or early summer, preferably at sunrise and never on young vines. Must be applied after Prep 500.
What is Prep 508?
Description: Horsetail plant boiled into a tea.
Use: Fights fungal infections.
Application Method: Can be combined with fungicide and sprayed on the vine or fermented first and sprayed on the soil during the waxing moon. Must be applied after Preps 500 and 501.
Name 3 teinturier grapes
- pontac
- alicante bouchet
- colorino
- chambourcin
De-stemming and cold soaking were innovations introduced by which winemaker?
Henri Jayer
How does humidity (below 70%) effect maturation?
- low humidity causes water to evaporate faster than alcohol
- unfavorably concentrates wine
- raises alcohol content
How long does post fermentation maceration last?
A few days to a few weeks
Describe the contact press method of tartrate stabilization
- wine cooled to 32 degrees F
- potassium bitartrate crystals added to speed precipitation
- filtered after 1 - 2 hours
What are the main benefits of a cross flow filter?
- handles large volumes
- very effective
- filters quickly
What is the purpose of fining?
removes unstable colloids to clarify and stabilize against haze and browning
Why is heat maceration useful against grey rot?
High temperatures denature laccase enzyme (highly potent oxidizing enzyme found in botrytis)
What is the main use of diatomaceous earth?
filter thick and cloudy wines (ex: lees-y)
What is the most effective method of post fermentation clarification in high volume wineries?
Centrifugation
How many average uses does a wood vessel get before becoming neutral?
4
In what ways can a winemaker mitigate smoke taint?
- must testing in lab
- hand harvest
- gentle while bunch pressing
- lower fermentation temps
- reduce maceration time
- flash detente/ reverse osmosis
Why would a bottle be sparged prior to bottling?
to reduce dissolved oxygen, which could speed up aging
What is the purpose of bentonite clay?
binds with protein that causes haze
How much SO2 is naturally occurring due to fermentation?
10 mg/L
What are the pros and cons of fining with gelatin?
Pro
- removes bitterness
- removes astringency
- removes browning
Con
- easy to over strip
- can form a protein haze
- not vegan
Why is European oak more expensive to produce than American oak?
- grows more slowly
- must be split into staves instead of sawn
What is Mytik Diam?
pulverized conglomerate cork treated for TCA
What are the pros and cons of fining with isinglass?
Pro
- very effective at brightening whites
Con
- can cause protein haze
- too much can cause fishy smell
Capsoni (220 L), quevri (2000-4000 L), and tinaja (400-600 L) are what types of vessel?
earthenware, amphora
(Puglia, Georgia, Spain)
Why would a wine with RS undergo sterile filtration?
sugar can start to re-ferment if not filtered out
What is the risk of a dry cap?
allows bacteria to turn alcohol into acetic acid
What times are considered the most effective for SO2 application?
- during crush
- end of MLF
What form of SO2 is the most effective against oxidation?
molecular (free) SO2
What countries are the 3 largest wine producers in the world?
- Italy
- France
- Spain
Describe reverse osmosis
- cross filtration removes permeate of alcohol and water
- permeate is distilled to remove alcohol
- watery permeate is blended back in
What is the purpose of fining with charcoal?
removes browning and off colors
What are 3 commonly used woods other than oak?
- chestnut
- cherry
- acacia
How does lees maturation help stabilize wine?
- stabilize whites against haze causing proteins
- protect from oxygen, reducing need for SO2
How can a winemaker reduce diacetyl characteristics of a wine?
delaying sulfur addition after MLF will allow lees to break down diacetyl
What are the outcomes of MLF outside of flavor?
- acid reduction
- raise in pH
- loss of color in red wine
- microbial stability
How does co-fermentation stabilize color in red wine?
white phenolic compounds bind to tannins to stabilize color
How is acetaldehyde produced?
oxygenation of ethanol
What is the EU max limit for SO2 in red wine?
160 mg/L
What is the primary effect of fining with casein?
removes browning
What are the chemical effects of autolysis?
- binds with grape phenolics to reduce color and soften tannins
- binds with wood tannins to reduce astringency
Methyl Anthranilate is responsible for what aroma?
“Foxy” aromas of vitis labrusca
In what year was INAO created?
1935
What enzyme is employed to stop MLF by killing lactic acid bacteria?
lysozyme
What is the purpose of a Ganimede tank?
CO2 is bubbled up through must to break cap as a quick method of high extraction
How long does short maceration last in rose making?
A few hours to a few days
How much sugar is in one degree brix?
1 gram sugar to 100 grams liquid
What is the optimal temperature range for MLF?
64 - 72 degrees F
What is the EU max limit for SO2 in white wine?
210 mg/L
What is the size of a demi muid?
600L
Intracellular fermentation results in what abv?
2%
What component of American oak is responsible for coconut aromas?
Lactones
What is the average time and temperature when cold soaking for red wine?
39 - 50 degrees F for 3-7 days
What is the purpose of fining with egg white?
gently removes harsh tannin
What is the cause of reductive elements produced by yeast under stress?
low nitrogen levels
What is the volume of a barrique?
225 L
What is the volume of a piece
228 L
What is the volume of a gonc
136 L
What is the name of the amphorae used in Puglia?
What volume does it hold?
Capasoni
220L
Black Locust and Robina pseudoacacia are names for what kind of wood?
Acacia
What is the size of a Feuilette in Chablis vs the Côte d’Or?
Chablis (132L) Côte d’Or (114L)
What ester is responsible for banana aromas?
isoamyl acetate
What is the largest drawback of using cherry wood?
causes swifter oxidative aging
What is the benefit of using acacia wood?
has similar porosity to oak but doesn’t impart woody flavors
Botti are made from what kind of oak?
Slavonian (Croatia)
What is the volume of an American Hogshead and where is this traditionally used?
300 L
Barossa Shiraz
What is the volume of a German Fuder?
1000 L
What is the volume of a Tonneau in Bordeaux?
900L (no longer used)
What is the volume of a Demi-Muid in the Southern Rhône Valley?
600 L
What is the volume of a Stück?
1200 L
What is the world’s largest barrel?
Heidelberg Tun (Heidelberg Castle, Germany)
- 220,000 gallons
What are the main sugars in grapes?
- glucose
- fructose
How is potential alcohol measured in the EU?
1% abv yielded per 16.83 g sugar per liter in must
What scales are used to measure density or gravity in must?
- brix
- baume
- oechsle
- KMW
What is the primary acid present in grapes?
tartaric
What chemical is responsible for bell pepper aromas?
methoxypyrazine
How much fruit can a machine harvester pick per hour vs a hand harvester?
machine - 10 to 20 tons per hour
hand harvesting - 1 ton per hour (working fast)
What allows more extraction from skin in white winemaking: destemming or whole cluster pressing?
Destemming
- allows more skin contact
- allows more grapes to fit in press
- reduces processing time
Whole Cluster Press
- minimizes skin contact
- clearer juice and fewer phenolics
In what red grapes are you likely to see whole cluster fermentation?
- pinot noir
- gamay
- syrah
What enzymes helps speed extraction in red winemaking?
pectolytic enzymes - break down pectin
For how long would a producer utilizing skin contact in a white wine generally leave the juice on the skin?
2-48 hours (short maceration)
What grape are good candidates for short maceration?
aromatic grapes
- gerwurtz
- muscat
How long does skin contact generally last in red winemaking?
10-21 days
How long does a cold soak usually last?
a few days to a couple of weeks
Describe thermovinification
- must is heated to between 140 to 180 degrees F for a period of 30 minutes to 24 hours
- must is often pressed directly after heating, and fermentation proceeds off of skins.
Describe flash detente
- must is heated rapidly to near-boiling temperatures (185 degrees Fahrenheit), then cooled rapidly using a vacuum
- results in the complete destruction of the berries on a cellular level
What is the French term for clarification via overnight settling at cool temps?
debourbage
Describe clarification via flotation
gas is pulsed through juice and solids float to the top
What is the most important yeast in alcoholic fermentation of wine?
saccharomyces cerevisiae
What bacteria is responsible for malolactic conversion?
oenococcus oeni
What is the temperature range for both red and white wine fermentation?
White mid 40s-mid 60s
Red mid 70s to low 90s
Define:
remontage
pigeage
delestage
- pump over
- punch down
- rack and return
What is the most recognizable flavor compound produced by malolactic fermentation?
diacetyl
Where was the technique of micro-oxygenation developed?
Madiran
How many barrels can one oak tree provide?
1-4
How much does a new oak barrel cost?
$450 American oak
$600 Hungarian oak
$900 French oak (or over $2000 for specialty)
What are the most well known oak forests?
Tight grained wood
- Allier
- Troncais
- Jupilles
Medium grained wood
- Nevers
- Bertrange
Looser grained wood
- Vosges
Course grained wood (used for spirits)
- Limousin
What is the French term for topping up?
ouillage (every 2-6 weeks during elevage)
What is the volume of a puncheon?
450-500 L
What are the French terms for free run and press juice?
free run - vin de gout
press - vin de presse
What is 2-isopropyl-3-methoxypyrazine also known as?
ladybug taint
TDN belongs to what family of compounds?
norisoprenoids (eucalyptus, camphor, raspberry, violet)
Lactic acid bacteria converts what acid to diacetyl?
citric acid
What is the USDA max so2 allowed in wine made with organic grapes?
100 mg/L
What is chitosan?
exoskeleton (shellfish) derived fining agent used to remove brettanomyces
What is the French term for the grape skin cap?
chapeau
What is cliquage?
macro-oxygenation
What formula converts brix to baume?
Brix = baume(1.8)
At what temperature will tartrates precipitate out of a wine?
25 degrees F
