Ch. 5: Fermentation & Still Wine Production Flashcards
1
Q
Pre-Fermentation
A
Priority to begin the winemaking process as soon as possible after harvest
Winemaker keeps grapes cool and covered
May use sulfur as a preservative while grapes en route to facility
2
Q
Sulfur in wine making process
A
Can be added to grapes or juice at any of several points
Combines with O2 to form Sulfur Dioxide (SO2)
SO2 inhibits growth of both yeast and bacteria
Reduces likelihood of premature fermentation and spoilage
3
Q
The Crush
A
Pre-fermentation nickname
Actual crushing of the grapes
Also everything that gets the juice ready for the initiation of fermentation
4
Q
Sorting
A
First stop for grapes – sorting table
Leaves, underripe grapes, damaged fruit, other debris removed
Rigorous selection – high production costs, reserved for high-end wines
5
Q
Crushing and Destemming
A
Grapes sent through crusher or crusher/destemmer
If destemming, grapes simultaneously separated from stem of the bunch
6
Q
Difference between crushing and pressing
A
Pressing – skins of grapes are broken and juice is allowed to flow, but no pressure applied
Crushing must be done gently
Too much force can cause release of tannins from skins and seeds
7
Q
Pressing
A
In white winemaking, contact between skins and juice is minimized
Grapes can go through up to three pressings
8
Q
Pressing - Cold Soak
A
More aromatic grape varieties that benefit from skin contact are allowed to macerate with juice for no more than 24 hours
9
Q
Free run juice (Press juice)
A
Movement of grapes from harvest causes many berries to burst open
Large amount of juice drains from the press immediately
Considered to be the highest quality
Rich in sugar and low in tannin
May be made into winery’s best wines
10
Q
Bladder press
A
Modern presses
Inflate a large balloon with air or water to squeeze the grapes
More flexibility
Less likely to crush seeds or burst open skin cells
11
Q
Pomace
A
Cake of dry, compressed skins and seeds that remain after final pressing
Composted
Made to make pormace brandies
12
Q
Pomace brandies
A
Marc
Grappa
13
Q
Must
A
Grape juice that’s destined for fermentation
May move to fermentation immediately or winemaker may make adjustments
14
Q
Must Adjustments
A
Acidification
De-acidification
Enrichment
Chaptalization
15
Q
Acidification
A
Addition of acid to the must
Addresses the issue of low acidity
Done with tartaric acid
16
Q
De-acidification
A
Achieved through potassium or calcium bicarbonate
17
Q
Enrichment
A
Addresses issue of insufficient sugar
Blending with grape juice or concentrated grape sugar
18
Q
Chaptalization
A
Sugar cautiously added to must before fermentation begins
Only enough sugar to achieve acceptable alcohol level in finished wine
19
Q
Other Must Adjustments
A
Raising or lowering the concentration of sugar
Adding or removing water
Procedures are highly regulated in many parts of the world
20
Q
Debourbage
A
Winemaker lets the juice settle for a day or two before allowing fermentation
Must be done to:
Let must adjustment fully integrate with juice
Wait for some of the solids to settle out of the solution – less sediment
Have time to process more grapes that will go into the same batch
21
Q
Fermentation
A
Complex biochemical process
Involves thirty successive chemical reactions catalyzed by a specific enzyme in the yeast
22
Q
Fermentation Process
A
Yeast cells attack sugar molecules
Break them apart to release energy
Smaller molecules that remain after yeast cells have split apart the sugar that are ethyl alcohol and CO2
After yeast worked its way through must in tank, virtually all fermentable sugar is replaced by alcohol and CO2
CO2 mostly dissipates in the air
Must has become wine
23
Q
Basic Fermentation Chemical Formula
A
C6H12O6 + yeast –> 2(C2H5OH) + 2 (CO2) + heat
24
Q
Sugar During Fermentation
A
90% of grape sugars fully converted to ethanol and CO2
Rest broken down into:
Glycerol
Succinic acid
Acetic acid
Lactic acid
Acetaldehyde
Ethyl acetate
Other alcohols (methanol)
25
Stainless Steel Fermentation
White wines often fermented in SS tanks
Inert – does not impact flavors of the wine
Airtight, easy to clean, easy temp control
26
Barrel Fermentation
Some white wines are barrel-fermented to add complexity
Introduce oak flavors and downplay fruit aromas
27
Other Fermentation Vessels
Wooden casks
Concrete vats
28
Initiating Fermentation
Yeast cells and spores found in and around wineries
Brought into the winery on harvested grapes
Remain in the winery from previous year’s fermentation
As soon as sugar rich juice is released from grapes, yeast cells jump in and begin feasting and multiplying
29
Preventing Fermentation
Sulfur added
Must may also be refrigerated
Prevents fermentation from happening too soon or with unwanted strains of yeast
30
Natural Fermentation
Use of native yeast cells
Can be effective and deliberate winemaking technique
31
Inoculation
Addition of must with commercially grown yeast
Gets fermentation off to fast start
32
Usage of Other Yeasts
Saccharomyces cerevisiae most common
Different strains used to add desirable flavors or aromas
To speed up or slow down fermentation
To achieve certain level of alcoholic strength
33
During Fermentation
As yeast cells multiply, must bubbles and foams
CO2 escapes
Grows warm
34
Fermentation – Best Temps for White Wines
Between 50 and 60 degrees
Best for retaining delicate fruit and floral aromas
35
Effects of High Temps During Fermentation
As temp increases, yeast cells become more active
Sugars converted to alcohol at faster pace
Fresh fruit and floral elements can disappear
Introduces cooked fruit aroma
36
Stuck Fermentation
If fermentation gets out of control
Liquid gets above 100 degrees
Yeast will likely die, fermentation will stop prematurely
37
Temperature Control During Fermentation
One of the most important things the winemaker does
Refrigerated jackets, coils, or panels
Before that, fall weather conditions and underground wine cellars
38
End of Fermentation
Fermentation is over when sugar is depleted and nothing left for yeast to consume
Can take several days to several weeks
39
When Alcohol Level Reaches More Than 14%...
Yeast can no longer survive
Residual sugar
Winemaker may stop fermentation when wine is intended to be off-dry or medium dry (fortified/dessert wines)
40
Malolactic Fermentation (Secondary Fermentation)
Conversion process that can take place simultaneously with primary fermentation
Strain of lactic acid bacteria decomposes malic acid in wine and converts it to lactic acid
Tart, apple characteristic of malic acid becomes milder and creamier
41
Diacetyl
Ester created as a by product of MLF
Imparts buttery aroma to wine
42
Wines that Benefit from MLF
Chardonnay
Chenin Blanc
Viognier
Have notes of butter, hazelnut, brioche, and dried fruit
43
Lees
Expired yeast cells and other solid particles in wine that sink to the bottom of tank/barrel
Wine is quickly removed from lees
44
Sur Lie Aging
“On the lees”
Wine is allowed to rest in contact with lees for extended period of time
Dead yeast cells decompose
Impart yeasty aroma, creamy texture, more complexity
45
Lees Stirring (Batonnage)
Lees is stirred back into the liquid
46
Sulfur Addition
After fermentation, sulfur level is typically checked again
Addition might be necessary to decrease chance of microbial spoilage or browning
Important if there’s residual sugar – can lead to fermentation after bottling
47
Clarification
New wine has cloudy appearance
Due to remaining yeast cells & other solids
48
Clarification Methods
Racking
Fining
Filtering
Centrifuge
49
Racking
Uses gravity
Allows suspended matter to settle to bottom of vessel
Wine drawn off the sediment and moved to fresh container
Several rackings might take place
Some tannins or proteins will remain in solution
50
Fining
Inert material stirred into wine
Attracts unwanted sediment
Separated from wine by racking
Gelatin, egg whites, bentonite clay
51
Filtering
Straining the wine through a barrier with very fine openings
Can eliminate contaminants that can cause spoilage – sterile filtering
Filtering carefully monitored as it could reduce desirable flavor molecules
52
Centrifuge
Laboratory equipment
Uses accelerated gravity to separate wine from heavier solids
53
Barrel Aging
Oak barrels allow for slow oxidation
Adds complexity
Chardonnay and Sav Blanc can benefit
54
Barrel Aging – New Wood
Can add:
Vanilla
Oak
Wood
Coconut
Toast
55
Blending
Different vats of wine may be blended together
Important for branded wines – need to recreate flavor profile consistently
Develops complexity/balance to create particular style of wine
56
Cold Stabilization
Chilling wine around 25 degrees
1 to 3 weeks
Then rack wine off the precipitates
57
Alternative to Cold Stabilization
Use of finely ground bis of potassium bitartrate
Initiate formation of tartrate crystals, after which may be filtered
58
Bottling
Last task
Bottling line receives bottles at one end
Fills them
Seals with cork
Installs capsule over neck
Labels them
Packages in boxes
Stored for shipment/sale
59
Crushing and Destemming – Red Wine
Required in red grapes
Skins used during fermentation process
Destemming can be done
Stems may be added back to provide additional tannin, flavor, complexity
60
Must Adjustment
Winemaker might adjust acidity or sugar levels or add tannin
Leaving stems in must or adding tannin powder
61
Maceration
Period of contact btw skins and juice
As skins remain in contact with juice, red/blue pigments are extracted from skins, along with tannins and flavor constituents
Few days to few weeks, longer
One of the winemakers most important decisions
62
Maceration – Longer vs Shorter Periods
Longer = Deeply colored, highly tannic, bursting w/ flavor, and need time to mature
Shorter = Softer, more accessible wines, ready to consume upon release
63
Maceration – Longer Period Examples (Wines)
Syrah
Cab Sav
64
Maceration – Shorter Period Examples (Wines)
Pinot Noir
65
Cold Soak
Winemaker chooses to begin maceration before fermentation
Must is chilled to below 55 degrees to postpone fermentation
Allows winemaker to control level of phenolics
66
Fermentation – Difference BTW White and Red Wines
Main difference – skins in must
Needs to be maintained during fermentation
Impacts selection of vessels, favoring use of large tanks over small wooden barrels
67
The "Cap"
CO2 produced during fermentation forms bubbles
Bubbles push grape solids to top of vessel
Solids = “Cap”
68
Cap Management
Extraction of phenolics requires skins to be in liquid, not on top
Acetobacter might grow on the cap
Might cause excess acetic acid
Trapped CO2 might cause cap to burst
69
Cap Management Methods
Punching down
Pumping over
Rack and return
Rotofermentation
70
Punching Down
Pushing cap into juice
Fench = Pigeage
71
Pumping Over
Pumping juice from bottom of tank and spraying it over top of the cap
French = Remontage
72
Rack and Return
Draining fermenting juice into separate tank before it’s returned to original tank by spraying it over now sunken cap
Considerably more aeration
French = Delestage
73
Rotofermentation
Agitating the fermenting must in specialized fermentation vessel
Vessel either rotates on its own or contains inner paddle that mixes
Usually controlled by computer
74
Fermentation Temperature – Red Wine
Higher than whites
Allows for increased extraction of phenolics
60 to 70 degrees for light Pinot Noir
85 to 95 degrees for Cab Sav
75
Extended Maceration
Skin is allowed to stay in contact with must for several days to several weeks
When fullest extraction of phenolics is desired
76
Malolactic Fermentation – Red Wines
Often spontaneous
Might be initiated with inoculation of lactic acid-producing bacteria
Done between beginning of fermentation and transfer into barrel
77
Pressing – Red Wine
Remaining solids pressed to release any remaining wine
Very rich in tannin and color – might be added to long-run wine or used in separate blend
78
Clarification – Red Wine
After pressing, wine might be moved to tank for clarification
One or more rackings likely performed
Might be filtered
79
Oak Aging – Red Wine
Can be beneficial
Especially for wines high in tannin
Use of young barrels add vanilla, toast, woodsy aromas
Many mid- and upper-range red wines spend some time in barrels
80
Polymerization
Slow infusion of O2 that seeps through wood into wine
Helps tannin molecules combine with each other
Tannins feel softer & richer
81
Variations in Oak Barrels – New Barrels
Impart significant flavor
Less oak flavor after each year
Most flavor leached out after four years
82
Variations in Oak Barrels – Larger Barrels
Have less effect than small barrels
83
Variations in Oak Barrels – French vs US
French oak = More subtle and refined in flavor
American oak = more assertive, less expensive
84
Variations in Oak Barrels – Handmade Over Open Fire
Bent into shape
Imparts toast or charring on wood
85
Barrel Choice
Winemakers choose shape, size, type of wood
Light, medium, or heavy toast
French oak barrique – high end wines
86
Micro-Oxygenation
Bubbling tiny amount of O2 into wine to simulate oxidation effects of barrel aging
87
Carbonic Maceration
Enzymatic fermentation
Doesn’t require yeast or bacteria
Whole, unbroken grapes placed in enclosed fermentation vessel
Blanketed with CO2
Enzymes break down grape sugars & create alcohol within berries
100% CM is rare
Breakage in grapes lead to yeast introduced in juice
Used in initial stages of wine production
Remaining sugar converted by normal fermentation
Primarily known for use in Beaujolais/Beaujolais Nouveau
88
Carbonic Maceration – Red Wines
Low in tannin, brightly colored
Tropical fruit and red berry aromas/flavors
89
Rose Wine
Pale pink
Dusty rose
Orange-tinged (salmon/onion skinned)
90
Rose Wine Styles
Still
Sparkling
Dry
Off-dry
Sweet
91
Color of Rose Wine
Determined by grape type
Amount of time spent in skin
Most common – juice sits with skins from few hours to several days
Juice is pressed off, fermentation continues
92
Alternative Methods of Rose Wine Production
Fermenting white grapes with red grapes
Blending small amount of red wine with white wine
93
Rose Wine – Saigniee Method
Produces both rose wine and concentrated red wine from same grapes
Red grapes crushed, destemmed, vatted from 2-20 hours
Certain amount of juice is run off to make rose
Remaining juice stays with skins to make red wine
94
Rose Wines – Direct Press Method
Pale roses (vin gris)
Grapes, destemmed or whole cluster
Crushed immediately after harvest
Juice is pressed
Short period of maceration
Resulting pale pink juice is fermented
95
Roses Should Always Be…
Fruity
Refreshing
Med to high acidity
96
Blush Roses
Slightly sweet
White Zin
97
Rose Wines – Other Terms
Rosado – Spain
Weissherbst – Germany
Rosato – Italy
98
Traditional View of Winemaking
Natural aspects of vineyard and production facility are paramount
Wine should reflect physical environment as much as possible
99
Alternative View of Winemaking
Grapes are raw materials to be molded into desired form by human artistry, expertise, and technology
100
Winemaker’s Most Active Time
Just before harvest through end of fermentation process
Remainder of year is slower pace
101
Non-Harvest Activities for Winemaker
Checks on progress of aging wines
Decides when to bottle
Plans for next vintage
102
Flying Winemakers
Winemakers who travel between northern and southern hemispheres to make wine twice a year
103
Sweet Winemaking Practices
Botrytis
Late Harvest
Dried Grapes
Freezing
104
Botrytis – Sweet Wine
Fungus affects the grapes at the right time
Causes water to evaporate from berries
Raises concentration of Sugar
105
Regions Known For Botrytis Sweet Winemaking
Sauternes area of Bordeaux
Loire Valley
106
Grapes Used in Botrytis Sweet Wines
Chenin Blanc
Semillon
107
Botrytis Aromas
Honeysuckle
Apricot
108
Late Harvest
Berries continue to gain sugar as long as there are leaves on vine
Begin to lose water
Lose acidity
109
Regions Known for Late Harvest Sweet Winemaking
Cool climates
110
Grapes Used in Late Harvest Sweet Wines
Chenin Blanc
Riesling
111
Winemaking - Dried Grapes
After harvest
Grapes allowed to dry and become partially raisinated
Dried grapes may be fermented into dry, high alcohol wines
Amarone – Italy
112
Freezing
Growers may leave grapes on vine until weather turns cold enough to freeze them
As late as Jan/Feb in Northern Hemisphere
Significant sugar content developed
Pressed immediately
113
White Grapes Used in Freezing Sweet Winemaking
Riesling
Gwertz
Chenin Blanc
114
Eiswein
Ice wine
115
Red Grapes Used in Freezing Sweet Winemaking
Cab Franc
116
Cryoextraction
Mechanical freezing process
117
Procedures for Making Sweet Wines
Refrigeration
Adding sweetness
Fortification
Killing yeast via pasteurization
Adding large amounts of sulfur
118
Sweet Wine Procedure – Refrigeration
Chilling must during fermentation
Stops yeast activity while there is sugar left
Sterile filtering or sulfur added to make sure wine doesn’t begin fermenting after bottling
119
Sweet Wine Procedure – Adding Sweetness
Wine allowed to ferment dry
Addition of sugar, grape concentrate, or unfermented juice
Risk of restarting fermentation unless protective measures used
120
Sweet Wine Procedure – Fortification
Adding distilled spirits during fermentation
Kills yeast before all sugar is gone
121
US Certified Organic Wines
Dept of Agriculture National Organic Program (DOANOP)
Wines made from minimum of 95% certified organic grapes
Nothing used that’s prohibited by NOP
Display USDA Organic Seal
122
Most Significant Restriction in Organic Winemaking – US
Use of sulfur
Wines can be labeled organic if made from certified organic grapes and sulfur dioxide yields less than 100 parts per million
123
EU Organic Wines
Vin Biologique
Must contain 30-50% less added sulfur than non-organic wines
No additives permitted
Winemaking process must be fully traceable
124
Biodynamic Wines
100% biodynamically grown grapes
Minimal manipulation and low impact on environment
125
Biodynamic Wine Certification
Based more on progress toward an extensive list of goals than strict criteria
Genetically modified materials prohibited
Sulfur use kept to minimum
126
Biodynamic Governance
Private org
Demeter International
127
Kosher Wines
Certified by Jewish religious authorities to conform to biblical law
For consumption of observant Jews
Can be made from any grapes
Materials can only be handled by observant male Orthodox Jews under supervision of a rabbi
Animal based products can’t be used
128
Mevushal Wine
Subcategory of kosher wine
Free from limitations on who may handle it
Briefly subjected to high heat before leaving winery
