Ch 16 White Winemaking Options Flashcards
White Winemaking
What are the 8 main white winemaking options?
- Skin contact
- De-stem vs whole bunch
- Hyperoxidation
- Must clarification
- Ferm temps and vessels
- MLC
- Barrel fermentation
- Lees aging
White Winemaking
What is skin contact, what is the purpose for whites and what is a caution?
○ Process of leaving juice in contact with grape skins to extract compounds from skins
○ Purpose - enhance extraction of aroma and flavor compounds and pre-cursors, enhance texture by extracting small amt of tannin
○ Caution - not suited to all styles - if too much can make wines too bitter and feel coarse
White Winemaking
How are non-skin contact wines made, how protect aromas and why?
○ Crushed then pressed immediately -> principle desirable aroma compounds are in the pulp
○ Some also use whole bunches of uncrushed grapes -> to further limit contact between juice and skins and reduce oxi
White Winemaking
What wine styles/situations are preferred for minimal skin contact wines?
○ Delicate, fruity flavors, minimal color, smooth mouthfeel
○ Early drinking wines -> tannins that would be extracted with skin contact wouldn’t have time to soften
○ If fruit is under-ripe -> skin contact would create bitter flavors and astringent tannins
○ Inexpensive wines -> skin contact takes time and is a step that requires equipment and labor
White Winemaking
When is skin contact used for whites?
Example?
○ Used most effectively on aromatic var that have lots of aroma compounds -> skin contact maximizes aroma/flavor extraction as well as texture
○ Examples -> Riesling, Gewurtz, Viognier, Muscat and SB -> all rarely matured in oak
○ Some winemakers feel skin contact leads to homogenization and reduction of uniqueness of var/vineyard sites
White Winemaking
What are the 2 key factors that influence extraction during skin contact?
What ranges/levels are used for these factors and why?
Time and temperature
○ Time - range from an hour to 24hrs+ -> more time = greater extraction
○ Temp - chilling wine to below 15°C reduces rate of extraction -> allows more control and reduces rate of oxidation and spoilage org threat -> incl likelihood of spontaneous ferm
○ Wine usually pressed to separate juice from skins before ferm
White Winemaking
How are orange wines made?
How different vs standard white process?
○ Whites grapes fermented on skins
○ Signif different taste and aroma -> more and different aromatic and phenolic compounds extracted from skins
○ Can have notable levels of tannins and char such as dried fruit, dried herbs, hay or nuts
○ Commonly made with “traditional”/low intervention methods -> ambient yeast, no temp control or SO2
White Winemaking
How is pressing generally approached in white winemaking?
○ Grapes almost always pressed to separate juice from skins before ferm
○ Usually as gentle as possible -> avoid extraction of unwanted color/tannin from skins/seeds
White Winemaking
What is a key choice before pressing?
What is impact if not done?
○ De-stem or use whole bunches
○ Whether to de-stem -> for whites, usually grapes are de-stemmed before pressing
○ Use of whole bunches -> reduces oxidation before and during pressing - esp if use inert gas w/in press;
○ It is one of gentlest forms of pressing -> juice is low in solids, tannin and color
○ Stems also help break up mass of grape skins -> provide channels for juice to drain
White Winemaking
What situations/conditions is whole bunch pressing an option?
What are other considerations?
What price points do this?
○ Only when hand harvested
○ Whole bunches take up more space in the press-> fewer grapes can be loaded each press cycle
○ Option for prem/super prem; less likely when making high vol inexp wines that need to be processed quickly
White Winemaking
What are the 2 kinds of juice in pressing process?
Free run juice
Press juice
White Winemaking
What is free run juice?
What are its characteristics?
What are the implications of making wine from it?
○ If grapes are de-stemmed and crushed - first juice that runs off
○ Lowest in solids, color and tannin
○ Lower in pH and higher in acid and more sugar
○ Wine can be made from free run only - lighter body, color style -> but lower volume of wine = cost implication
White Winemaking
What is press juice?
What are its characteristics?
What are press fractions and characteristics?
○ Press juice - juice that runs off from pressing
○ At beginning - same as free run
○ As pressing continues and more pressure applied -> more solids, tannin and color extracted -> also lower acidity and less sugar vs free run
○ Press fractions - winemaker can separate press juice into batches as pressing continues - each has greater pressure -> more extract
○ Last press fractions likely to be too astringent or bitter -> not used
White Winemaking
What is hyperoxidation?
Why do it?
What is the goal/benefit?
What are considerations?
Example?
○ Technique of deliberately exposing must to large qty of O2 before fermentation
○ Targets compounds in must that oxidize most readily -> turn must brown
○ During ferm, these compounds precipitate removing brown color
○ Goal - make wines more stable against oxi after ferm; also can remove bitter compounds from unripe grape skins/seeds/stems
○ Consideration - can destroy some of most volatile aroma compounds -> better for non aromatic var
○ Eg - can reduce levels of thiols and methoxy in SB -> don’t do it for fruity/herbaceous style
○ Economics - equip not too expensive, but it adds a step and req labor -> small impact on costs
White Winemaking
When does must clarification happen and what is the goal?
What is needed for lower levels?
When are lower/higher levels preferred?
Prem vs inexp examples?
○ Between pressing and fermentation (can also happen after ferm)
○ Goal -> reduce amt of suspended solids in must
○ Generally want prop of solids to be 0.5-2%
○ To get levels below 1% -> need pectolytic enzymes or centrifugation
○ Some winemakers keep 1-2% because adds texture and gives subtle astringency as well as greater range of aromas from ferm
○ Lower levels better for fruity wines
○ Premium Chard -> higher levels of solids may be preferred
○ Inexp PG -> lower levels preferred for fruity aromas
White Winemaking
What are considerations for must with higher levels of solids?
What are examples of risks?
What price point best for?
○ Ferm need to be carefully monitored -> compounds in solids and their reactions can lead to off aromas/flavors
○ E.g., - can create reductive sulfur compounds -> low levels ok (matchstick) but high levels reductive sulfur/rotten egg
○ Need for close monitoring means better for small batch, premium wines
White Winemaking
What is a small amount of solids in the must good for most wines?
○ Adds nutrients for yeast
○ Over clarifying has risk of stuck ferm
○ Must w/ very low level of solids also need careful monitoring -> may need to add yeast nutrient (DAP)
White Winemaking
What are the options for clarification of grape must?
- Sedimentation
- Flotation
- Centrifugation
- Clarification agents
White Winemaking
What is sedimentation and another name for it?
How is it done, why is it done?
What factors impact how long it takes?
What are economic considerations?
aka - settling
○ Simplest form of clarification - solids fall to bottom from gravity ○ Clear juice transferred to ferm vessel ○ solids left behind -> often filtered by cross-flow or depth filters to extract more juice ○ Factors impacting how long: § Temp - must commonly chilled to 4°C to reduce rate of oxi and risk of spoilage orgs and avoid spontaneous ferm § Size/shape of vessel - tall take longer ○ Sedimentation at low temps takes longer - 12-24hrs -> ties up tank space
White Winemaking
What are adv and considerations of sedimentation as must clarification technique?
What price point used for and why?
Adv
○ Cheapest form in terms of equip
○ most traditional way of doing it -> no extra equip or additives
Considerations ○ Takes the most time ○ Energy cost from chilling ○ Batch process - labor and time ○ Most common for small production/premium
White Winemaking
What is flotation?
How is it done, what needs to be added, and how does it compare to sedimentation?
Advantages/considerations?
○ Bubble gas up thru must -> as gas bubbles rise they bring solids with them -> solids skimmed off top
○ Faster than sedimentation
○ Inert gas usually used - N
○ If use O2, it is a form of Hyperoxidation
○ Fining agents must be added to must to bind to particles
○ Can only be done on must, not wine
○ Adv - quicker, can be done in batch or continuous, no energy cost for chilling
○ A little more $$ than sedimentation -> equipment, gases, fining agents
White Winemaking
What is centrifugation?
How is it done?
Advantages/considerations?
○ Machine w/ rapidly spinning chamber that uses centrifugal force to separate liquids from solids
○ Adv - fast, continuous (vs batch) saves time and money; can be used on wine and must
○ Disadv - expensive to buy -> usually in high vol wineries; inc must exposure to oxi unless filled w/ inert gas
White Winemaking
What are clarifying agents?
What is the main one used?
How does it work?
Considerations?
○ Variety of compounds can be added to must to speed up sedimentation
○ Pectolytic enzymes - break down pectins in must - come from plant wall cells
○ Breaking down pectins allows more rapid separation of liquid and solids
○ Pectolytic enzymes - can only be used for must
○ Cost- purchase agents - but usually worth it in time/energy saved vs sedimentation
Benefit - quick and effective - can be continuous or batch process
White Winemaking
How do white ferm temps compare to reds and why?
What temp is generally used?
○ White ferm temp cooler -> volatile aroma/flavor compounds - esters - best produced and retained at cool temps
○ Usually ~15°C
White Winemaking
When are warmer ferm temps ok for whites?
What temp range and why?
○ Whites where fruity aromas not desired - white mat in oak
○ Warmer temp range - 17-25°C -> promote yeast health and avoid production of certain esters - eg. Isoamyl acetate (banana aromas)
White Winemaking
What are common ferm vessels for fruity/floral whites and why?
Examples?
○ s/s most common -> able to control temps and maint cool ferm temps to enhance aromas
○ Concrete and old oak also used at slightly warmer temps where maximizing fruity aromas is not main goal - e.g., some Chablis and white Rioja
White Winemaking
When are small oak barrels used (price point) for white fermentations?
Why and what are advantages/considerations?
○ Prem/super-prem chard
○ Adds cost - barrels expensive, large number needed, monitoring ferm more labor intensive
○ Adv -
§ deeper color, fuller body -> oxidative environ;
§ also more integrated oak derived aromas from action of yeast during ferm
§ Small size of barrels -> inc contact bet wine and lees = texture
§ Can create more blending options -> barrel differences
○ Less likely to be used for aromatic var -> preserve floral/fruity aromas
White Winemaking
What are the impacts of MLC on a wine?
What are then implications of the choice for aromatic vs non-aromatic wines?
○ Reduces acidity (inc pH), inc in microbio stability and modifies flavors
○ MLC conscious choice for winemakers in whites -> impact on final wine have big impact on style
○ Low aromatic var (chard) -> tradeoff bet perceived greater complexity of MLC wine vs fruit char of non-MLC wine
○ Aromatic var (Riesling, SB) -> MLC usually avoided to preserve primary aromatics -> maintains varietal distinctiveness
○ Winemakers can adjust acidity and also reduce alc at this point
White Winemaking
What is the impact of barrel maturation for whites?
What wines/ price points are likely to be barrel matured?
What are economic considerations?
Examples?
○ Has signif impact on style and price of wine
○ Low aromatic, prem/super prem (chard) likely aged in small oak barrels -> texture and complexity
○ Aromatic (Riesling) - not likely to be barrel matured -> vanilla/toasty nutty aromas and flavors from oxidation not desired -> overwhelm aromatics
○ Costly to use oak barrels - beyond prem/super-prem will use oak alternatives
White Winemaking
What is the goal of lees aging?
How are reds vs whites different in consideration for it?
What price point do it?
○ Add body, soften mouthfeel and help stabilize wine
○ Protect from O2 and can introduce low levels (desirable) of some reductive sulfur compounds - matchstick, smoke
○ Thought to be more impactful for whites than reds
○ Common across range of price points - less done on inexp ->release for consumption asap
White Winemaking
Why stir lees and what is another name for it?
How is it done?
What are considerations?
○ Aka Bâttonage
○ Inc release of yeast compounds
○ Traditional - use rod an manually stir lees into wine -> removal of bung inc O2 exposure = inc in effects from dead yeast and decrease in fruity flavors, also reduces dev of reductive sulfur compounds and off aromas they can produce
○ Modern - can mix w/o opening vessel -> more control over O2 exposure
○ Lees stirring on large number of barrels - labor intensive - higher costs
