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Red Winemaking
Fermentation Temperature
Skin and seed contact time
Extraction Techniques
Cold Soak
Thermovinification
Extended Maceration
Pre-fermentation Juice Runoff
Enzyme Additions
Reds Ferment Warm
Most reds ferment at warm temperatures (70-90F)
Oxidation is generally not an issue because surface layer of CO2
Skins and seeds are less dense than fermenting liquid forming a cap (about 1/3 volume)
Cap requires mixing to prevent drying
Mixing techniques vary and influence the color and astringency of the wine
Seed And skin Contact
Duration of contact time is controlling factor for extraction of color and tannin extraction.
Tannins impart astringent character to wine and act as a color stabilizer
Alcohol also helps to extract color and tannin
Higher tannin is desirable in wines that are meant to be aged (unpleasantly too tannic young)
Pigment Extraction
Anthocyanins are the water soluble pigments that are extracted from the skins of the grapes.
Copigmentation:Anthocyanins interact with themselves and other colorless cofactors to provide color beyond what would be expected from themselves.
Anthocyanins are susceptible to bleaching by sulfur dioxide. Smalllosses due to this are acceptable during winemaking.
Tannin Extraction
Tannins are water soluble compounds that impart astringent character.
Tannins and other compounds can combine with anthocyanins to stabilize color known as “polymeric pigments.”
Polymeric pigments are more stable to sulfur dioxide bleaching.
Rates of Extraction
Anthocyanins
Extracted after two to three days
Decline after maximum reached
Tannins
Extracted slowly and increase with contact time
Polymeric Pigments
Formed during winemaking and aging
Mixing TechniquesPunch-Down
Device used to break up cap and submerge it into fermenting liquid
Pump-Over
Volume of liquid is taken from racking valve and pumped back onto cap to wet it.
Rack and Return
Entire volume of liquid is racked off and then poured back onto cap to fully submerse it.
Often seeds are removed from bottom of tank during this process to avoid extraction of bitter compounds.
Punch-down vs. Pump-over
Which method is more effective?
It depends on the cultivar.
Also depends on whether mechanism is mechanical or manually based.
Pump over has been found to be extractive technique in many cases.
Pump over variables
Duration of pump over
Cap temperature during pump over
Skin content of liquid
Special Apparatus: Rotary Fermentors and Pulsed Air
Rotary Fermentors
Horizontal Fermentor
Mechanically rotates
Mixes during rotation
Pulsed Air
Compressed gas at bottom of tank
Inert gas
Forced through cap
Cold Soak
Must is held at low temperature prior to fermentation (10 to 15C)
Winemakers claim it improves color
Done with varieties that are low in anthocyanins such as Pinot noir.
Prominent technique for Oregon Pinot noir production
Cold soak continuedAqueous extraction supposedly improves wine color
Anthocyanins are extracted early in fermentation while tannins are later.
Heat and alcohol are prominent extraction elements
Anthocyanins are unstable and highly reactive and can degrade or be stabilized by other compounds
Stable color = Polymeric pigments formed through reactions with tannins and anthocyanins
No good evidence it enhances stable color formation.
Likely cold soak combined with other extraction methods may be able to help improve wine color but not on its own.
Thermovinification
Procedure:
Pre-fermentation heating of skin/seeds (140 to 160F) for a short time
Extract with juice
Press
Cool
Start Fermentation
ThermovinificationResults:
Damages skin cells (hypodermal cells)
Denatures oxidative enzymes
Release of anthocyanins
No tannin enhancement
Good for color improvement
Suggested for varietals that have low color
Research demonstrated effective with Pinot noir
Extended MacerationProlonged skin/seed contact after primary fermentation is complete
Cultivar not a factor
Tannins and anthocyanins
Time period variable
7, 13, 21 and 44 days have reported in literature
Tank space can be become an issue
Winemakers discuss this method as a means of building body for the wine not just astringency
Pre-fermentation RunoffSaignée: Bleed off
Removal of free run juice before fermentation
Increase of skin/seed to juice ratio
Used to simulate variation in berry size w/out change in berry composition.
Phenolic Enhancement
Color, tannin, polymeric pigment, total phenolics
Varietal Differences
Enhancement lost in some cases over time
Enzyme AdditionsPectolytic enzymes
Enzyme = protein that is able to accelerate reaction without being used as substrate
Lysis=breakdown
Pectins are water soluble polysaccarides that are found in the cell walls of plants
Most enzyme preparations are impure
Can contain enzymatic activities that will destabilize anthocyanins
beta-glycosidases destabilize anthocyanins
Enzyme additionsEnzyme mixture “cocktail”
Difficult to know what enzyme activity you have in cocktail
Research findings:
Anthocyanin extraction not enhanced
Tannins and other phenolics are enhanced
Polymeric pigments
Enzymes are affected by pH, EtOH, Temperature
Some empirical investigation required
Role of Pressing in Red Winemaking
The end of extraction of skin/seed components
Determining when to press depends on wine type
Different types of presses are used to achieve different outcomes
Bladder presses are the most commonly used
Screw and basket presses are old effective means
Continuous presses are more rare
Both screw and continuous presses are avoided because they often damage seeds and skins and extract unwanted components
ExperimentMerlot (Columbia Basin 5 ton/acre)
10 ton fermentor (2 reps)
TreatmentSaignée
%Water
AdditionVolume Change
Brix Target
Contact Time
Control 0% 17.50% +17.5% 23.8 Brix 7 days
High Alcohol 0% 5% +5.0% 26.8 Brix 7 days
Low Saignée 18% 14.50% -3.50% 23.8 Brix 7 days
High Saignée 22% 11% -11% 23.8 Brix 7 days
Extended Maceration 14.60% 10.60% -4% 23.8
Brix 20 days
Extraction Proportions
ControlHigh
AlcoholLow
SaignéeHigh
SaignéeExtended
MacerationSkin
Tannin 42% 26% 40% 27% 22%
Seed Tannin 58% 74% 60% 73% 78%
Wine Tannin (Calc)
622 mg/L 976 mg/L 803 mg/L 977 mg/L 1704 mg/L
Wine Tannin(Act.)
552 mg/L 665 mg/L 547 mg/L 811 mg/L 1080 mg/L