7. Common Elements in Winemaking and Maturation Flashcards
oak vessels - 4 factors to consider
- origin of oak (Europe or US)
- size of vessel
- production of oak barrels
- age
oak alternatives
- planks/staves (Stifte)
- chips
- inserted during or after fermentation
- oxidative effects through small amounts of oxygen added
advantages of inert vessels
- stainless steel:
- any shape
- easy to clean
- temp control
- concrete (lined with epoxy resin)
- easy to clean
- control temp without expensive equipment
destemming and crushing
- optional
- no stems if machine harvested
- most want stems to be removed (flavours)
- done through destemming machine, that then crushes (cracks skins of berries open)
Pressing - def? types? juice?
- separate liquid from solid components
- traditional: vertikal basket press (still used in Champagne)
- modern: pneumatic press, more control
- pressings=fractions, different beginning and end (see Press Wine), so used for blending
adjustments - when? what (2)?
- before, during or after fermentation
- adding sugar
- adding/removing acid
adjustments - sugar and alcohol - when? where? what? alternatives? contrary?
- when not enough ripen, i.e. must weight to low
- cooler climates: Chablis, Loire (Muscadet), Germany, England
- added through Rectified Concentrated Grape Must (RCGM) before or during fermentation
- removing water - concentrates also tannins and everything else
- contrary: removing sugar is very difficult, but removing alcohol is today possible
adjustments - acid - when? what? where? where deacidification - where? - how?
- when during ripening levels too low
- addition powdered tartaric acid
- only in warmer regions
- deacidif.: in cooler climates, adding alkali (i.e. opposite of acid)
fermentation -why Saccharomyces ceverisiae? temp? how to stop (3)?
- resistant to SO2 and fairly high alcohol
- temp range 5-35°C
- remove or kill yeast (SO2, grape spirit alcohol), cool down
fermentation - ambient yeast?
- pro: complex flavours
- con: hard to control, big variations
fermentation - why temp control important? overall?
- low: keep flavours (whites)
- higher: extract colour, tannins (black varieties)
- tight temp control technology has huge impact on more consistent wine quality
MLF? what? how? when?
- malolactic fermentation, turning malic acid into lactic acid (creamy, buttery flavour, softening acidity)
- after alcoholic fermentation through lactic bacteria
- how: no SO2, higher temp
- avoid through SO2, lower temp, filtering bacteria
- mostly for non-aromatic: Chardonnay, Pinot Gris
Pre-bottling maturation - lees - what? how?
- directly after fermentation wine can appear cloudy
- gross lees (dead yeast cells, grape fragments) will sediment quickly and need to be removed (unpleasant aromas)
- fine lees: sediment less quickly and are being removed gradually through maturation.
- winemaker may choose to keep white wine in contact with fine lees to add extra flavour and texture
Wine components - 6
- sugars: 0.1-20%
- acid: 0.3-1% (tartaric, malic, lactic)
- aroma and flavours: <0.2%
- ethanol: 8-22%
- tannins and colour: <0.4%
- water: 70-90%
what’s critical for pre-bottling maturation? when? components 4?
- if want to retain primary then no maturation
- need acid, alcohol, tannin, aromas that will develop in an interesting way
blending - when? impact on (3)? examplease
- vital role in entire winemaking process
- after fermentation or maturation
- impact on:
- balance: blend free run wine with press wine to increase tannins
- consistency: from different vats due to variation in fruits (vineyards, harvest) or during winemaking
- style: often important to get a house style (simple, complex wines)
Clarification - why? how 3?
- consumer expects wine to be clear
- sedimentation
- fining
- filtration
sedimentation, racking? how to accelerate?
- racking: once gross less is settled then gently pump from one vessel to another but leaving sediment behind
- accelerate through centrifugation but very expensive
fining? important?
- fining agent enhances that wine constituents clog together and form lager components that can easily be removed through filtering
- widely practiced and important step
filtration? -when? what? types - 3?
- after fermentation or during maturation
- filter gross and fine lees
- depth filtration: gross lees, thick material
- surface filtration: fine less, small pore size and clog quickly (expensive)
- sterile filtration: like surface filters but against microbes
stabilisation - def? 3 important areas? what’s at risk? what can be done?
- def: stable if it changes in a predictable manner, differs from wine to wine (e.g. simple, cheap vs Port)
- tartrate (crystalized tartaric acid) stability: forms over time and at low temperature, can be removed when cooling <0°C
- microbiological stability: bacteria& yeast
- fortified wines: no risk
- dry, high acid, MLF wines: little risk but no guarantee
- low-acid, low-med alc, low sugar: higher risk –> sterile filtration, SO2
- oxygen stability: mostly during filling, reduce exposure to oxygen, keep SO2 levels ok,
- flush bottles with CO2 or N2 before filling
bottles - glas vs plastic? pros? cons?
- glas
- con: heavy, rigid, leaves air once started
- pro: strong, air-tight, for long-term storage
- plastic (bottles, bag-in-box):
- pro: light, cheap, bag avoids fast oxidation through vacuume
- con: not air-tight, wine in plastic bottles oxidises quickly, in bags: to be consumed within 18 months, i.e. not for long-term storage
bottle closures - factors to consider (2)?
- needs to seal well and protect wine
- needs to allow ageing in bottle (depends on amounts of oxygen let passing through)
cork taint - caused y?
- TCA= trichloroanisole
synthetic corks?
- generally made from some sort of plastic
- usually only for wines to be consumed within a year
- some premium version for longer term storage
screw caps - started where? oxygen? ideal for?
- initiated in Australia and New Zealand
- no oxygen exchange
- ideal for primary aromas preservation (e.g. white wines and some reds)
- research ongoing with screw caps allowing some oxygen in
post-bottling maturation - what’s required?
- darkness, 10-15°C, lying down so cork remains moist
