Ch 18 Specific Options for Red Winemaking Flashcards
What are the general aims in red winemaking?
Extracting anthocyannins, tannins and flavors from grape skins in such a way that the wine is suitably concentrated and balanced, without extracting too much
What general factors affect extraction?
- Temperature - hotter=more extraction
- Time on skins - more time on skins, more they are mixed = greater the extraction
- The medium in which extraction is happening = tannins most soluble in alcohol (i.e. fermented wine), anthocyanins are most soluble in water-based solutions (grape must)
What is the relationship between anthocyanins, tannins and oxygen?
Anthocyanins give color to red wines.
On their own, these molecules aren’t very stable and the color they bring to wines can be easily lost.
Anthocyanins become more stable when they bind with tannins, providing greater color stability
Oxygen facilitates this reaction between anthocyanins and tannins - so any winemaking processes that encourage gentle oxygenation of red wine promote color stability (eg micro-oxygenation, barrel ageing)
What are the two methods of maceration before fermentation and their main difference?
Cold soaking vs macerations using heat
Cold soaking provides gentlre extractions that are slower and easier to monitor control. promote color extraction w/o high tannin extraction. usually for premium wines
- cost in chilling + time taken, occupying tank space = not suitable for high volume produciton
Heat - flash detente or thermovinification - extract high levels of anthocyanins and flavors quickly
- vacuum system expensive - best for HV wineries
At what temps are juice and skins typically chilled during cold soaking? Why?
4-10C (39-50F), 3-7 days
- reduce rate of oxidation
- prevent bacterial spoilage
- avoid risk of spontaneous fermentation
What are the differences between flash détente and thermovinification?
Thermovinification - heating must to around 50-60C (122-140 F) - can range from minutes to hours - higher temp, shorter maceration
- can denature oxydative enzymes in grey rot
Flash détente - destemmed grapes are heated to 85-90C (122-140F) (higher temps than thermovinifiaction), then quickly cooled under a vacuum - rapid extraction of anthocyanins and flavors but avoiding cooked flavors
- can be used as treatment for smoke taint
- can denature oxydative enzymes in grey rot
What are the reasons for mixing the skins (cap) with juice/wine during fermentation?
- Equal dissolution of compounds throughout juice (not just bit near cap at top)
- Prevent bacteria from producing acetic acid (dry cap allows this)
- Gentle oxygenation and aeration, preventing reductive sulfur compounds
- Temperature control + heat distribution
What choices can a winemaker make surrounding cap management?
- techniques
- punching down
- pumping over
- rack and return
- Ganimede tanks
- rotary fermenters - Frequency + duration of mixing (eg. 3 pumpovers a day, 15 min each)
- timing within fermentation - if earlier on (less alcohol), then more colors + less tannins extracted; if later (more alc, tannins are alc soluble) more tannins extracted
- Temperature - more extraction @ warmer temps; temp controlled vessels can be used to cool down wine @ end of fermentation to extract less tannins
Describe the punching down method.
What is its french name?
- plunger submerges cap of grape skins in liquid - gentler
- can be hand or mechanized - if hand, this is labor intensive + costly plus need small vessels (so low volume premium wines)
French = pigeage
Describe the pumping over method.
What is its french name?
Juice/wine is taken from bottom of vessel and sprayed over cap of skins
Sprays liquid rather than breaking up the cap - extraction is gentle, usually combined with other methods to extract enough color, flavor, tannins
Aerobically - opening vat, splashing wine along inside - prevent reductive off flavors
Anaerobically- attach hose to tap at top of vessel
less labor intensive, can be pre=programmed
French- remontage
Describe the rack and return method.
What is its french name?
- Juice is pumped from one vessel into another vessel, then back into original vessel over cap at the bottom
- more extractive method - only 1-3 times w/ pumping over and punching down
- common for red wines requiring high level of color, tanninand flavor extraction (CS, Syrah)
- labor to perform and monitor, available extra clean vessel
- French: delestage
Describe the Ganimede method.
Method: bubble CO2 through must/wine until pressure bursts cap
Quick, efficient extraction - suited for wines w medium to high levels of color, tannins and flavor intensity (CS, Syrah)
Can be fully automated (unlike rack and return), less labor intensive
Specialized tanks more expensive than standard SS tanks
Can be done w/ O2 if winemaker wants oxygen exposure during fermentation
Describe the rotary fermenters method.
Rotary fermenters- closed, horizontal stainless steel tanks
Internal blades break up cap as tank rotates - increases surface area/contact between grape skins and juice
Quick, efficient extraction - suited for wines w medium to high levels of color, tannins and flavor intensity (CS, Syrah) - Aus Shiraz, high vol Central Coast CS
Can be fully automated, less labor intensive
Specialized tanks more expensive than standard SS tanks - need large volumes to make cost effective
Best for high volume, cheap or midpriced wines - premium wines need more gentle, precise extraction
What does must concentration involve?
this is the saignée method
you “bleed” the must and run off some of the juice, concentrating the must before the start of ferment - volume of juice is reduced, but you can make rosé from the juice that is removed
eg Bordeaux Clairet
What does co fermentation involve?
Co-fermenting a small proportion of white grapes (up to 5%) with red wine fermentation.
Some phenolic compounds from white grapes can increase color intensity and stability by binding with anthocyanins
Contribute aroma compounds
ie Viognier with Syrah
ojo: too much can lead to dilution
