Ch 16 Specific Options for White Winemaking Flashcards
Where would skin contact be desired by the winemaker?
Where would it be avoided?
DESIRED
- if wanting to enhance extraction of aroma, flavor compounds and small amount of tannin
- aromatic grape varieties w/ lots of aromas to extract- Viognier, Muscat, Riesling, SB, Gewurtzaminer
- enhance texture in aromatic varieties that don’t see oak
AVOID
if making a wine with smooth mouthfeel, delicate fruity flavors and light color
if wine is early-drinking
if fruit is under-ripe - bitter flavors, tannins
if wine is inexpensive - skin contact requires time and labor
What factors influence extraction during skin contact?
TIME
- can range from 1-24 hours
TEMP
- chilling juice reduces rate of extraction of flavros and tannin + reduces rate of oxidation and spoilage threat -usually chilled to below 59F
In which case will grapes skins not be pressed off before fermentation?
When making orange wine, where wine is fermented on skins.
Diff aromatic and phenolic compounds extracted at this stage.
Often involve other traditional methods- minimal intervention, ambient yeasts, w/o temp control, no additions of SO2
Why would a white winemaker choose to press whole bunches of grapes?
usually white grapes are destemmed and crushed before pressing
whole bunches can be pressed to, in order to:
- reduce oxidation before and after pressing - use inert gases
- gentlest forms of pressing - low solids, tannins and color
- stems break up skins
ONLY an option if:
- grapes have been hand-harvested
- making small batch, premium wines – fewer grapes can be loaded per press cycle, less quick and efficient press, more time/$$
What is free run juice? Characteristics and use for winemaker
- The juice that can be drained off as soon as grapes are crushed
- characteristics: lowest in solids, tannin and color; lower in pH, higher acidity
- use: can be used to make wine (100%free run juice), but lower volume so cost implication
What is press juice? Characteristics, use
- the juice that runs off through the pressing
Characteristics; similar to free run juice at the beginning, but as pressing progresses and more pressure is applied more solids, color and tannin are extracted; lower acidity and less sugar
Use: can be separated into parts - press fractions- and blended for added texture, complexity, body
What are the main aims of hyperoxidation? When would this process be carried out?
hyperoxidation - exposing the must to large quantities of O2 before fermentation; must turns brown at first but returns to normal color during fermentation
AIMS
- stabilize wines against oxidation after fermentation
- remove bitter compounds from unripe grape skins, seeds, stems
- can affect volatile aromas, so best for non-aromatic varieties like Chard
What are the aims must clarification?
Why would a winemaker leave a higher percentage of solids in the must?
AIMS
- reduce amount of suspended solids in must like grape skins, seeds and stems, aiming for 0.5-2% proportion of solids
Benefits/cons of higher percentage of solids
+
can add to texture
can add greater range of aromas from fermentation - add complexity - premium Chard
can give reductive aromas - low levels struck match, complex
provides nutrients for yeast, overclarifying can lead to stuck fermentation
-
lower levels better for fruity aromas - inexpensive PG
can give reductive aromas - too high levels rotten egg, faulty
needs monitoring to avoid reaching reductive aromas
What are the different methods of must clarification?
- Sedimentation
- settling - solids in must fall over time w/ gravity, need cool temps (59F) to reduce rate of oxidation, spoilage, spontaneous fermentation
- ADV: cheapest. simplest, most traditional
- CON: most time required, batch process (not coninuous)
** SMALL PRODUCTION, PREMIUM - Flotation
- gas bubbled through must. as gas bubbles rise they elevate solid particles which are then skimmed off top
-ADV: quicker than sedimentation, effective, can be used for hyperoxidation, no need to chill, continuous
- CON: more $ in terms of supplies - Centrifugation
- rapidly rotating container uses centrifugal force to separate liquids from solids
- ADV: quick, continuous (not batch), , saves time and labor
- CON: expensive to buy, increased exposure to O2, need to buy inert gas
**cost + quick.= best for high volume bulk wine - Clarifying Agents
- use of compounds like pectolytic enzymes to break down pectisn and allow a rapid separation between liquids and solids
ADV: quick, some can be used for wine clarification too, time _ energy saving
CON: cost of buying agents
What fermentation temps and vessels are most commonly used for production of fruity white wines? WHY?
TEMP: cool temps (15C / 59F) –> volatile aromas and flavor compounds (esters) are produced/retained at cool temps
Vessels: Stainless steel tanks - able to control temp, keep cool conditions, neutral/don’t impart additional aromas
ex’s SB, Veneto PG
What fermentation temps and vessels are most commonly used for production of neutral, non-fruity white wines? WHY?
TEMP: warmer temps (17-25C/ 63-77F) - promote yeast health, avoid production of fruity esters (like isoamyl acetate)
Vessels: concrete, old oak vats, stainless steel
ex’s Chablis, White Rioja
What are the advantages and disadvantages of using small oak barrels?
**common in premium/super premium Chard
+
deeper color, fuller body (oxidative environment)
more intergrated oak aromas.- yeasts during fermentation help integrate
texture - more contact between wine and lees
blending options - wines may be different after ferment process
-
adds cost.- buying barriques
adds labor need - monitoring
What are the effects of malolactic conversion?
- reduction in acidity
- increase in pH
- increase in microbiological stability
- modification of flavors - apple to yogurt; melted butter before browning
- usually avoided in aromatic like SB, Riesling
Considerations for maturing white wines in barrels
- type of grape - neutral (like Chard) benefit more from added texture and complexity than aromatic varieties like Riesling - nutty, toasty flavors not wanted
- cost - premium and super premium wines; oak alternatives like staves can be used for cheaper ex’s
Aims for lees ageing for white wines
Additional considerations
AIMS
- add body
- soften mouthfeel
- stabilize wine
- protect from oxidation
- introduce reductive sulfur compounds which add complexity at low levels
to stir or not to stir - lees stirring= batonnage -
- can increase release of yeast compounds in wine
- can increase rate of oxidation - every time you have to open bung from vessel to add rod and stir (so less fruity) but also reduces development of resuctive sulfur compounds and off aromas
- other alternatives to stir lees without opening vessel - add hose to tank and letting is run ; barrel racks
- lees stirring adds to labor costs
