Red Wine Maceration

Jim HarbertsonWashington State University

Red Winemaking

Fermentation Temperature

Skin and seed contact time

Extraction Techniques

Cold Soak

Thermovinification

Extended Maceration

Pre-fermentation Juice Runoff

Enzyme Additions

Red winemaking

Mixing Techniques

Pressing

Some Experimental Results

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)

Red FermentorAnatomy of a red fermentation

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

Extraction Profiletannin and anthocyanins

Polymeric pigmentFormation

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

Punch-downExample

Punch-DownMechanical device

Pump-over

Pump-overFixed irrigator

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

Pulsed Air to Mix Cap

Rotary fermentor

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

Anthocyanins7 days not 3 days

Tannin Extraction

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

ConclusionMany mixing techniques

Many maceration techniques

Experiment to find the ones that fit your style

Acknowledgements:

WAC

Chateau Ste. Michelle