Winemaking Flashcards
What are the constituent parts of the grape?
Seeds, stems and skins which contain tannins, the pulp which contains sugar, water and acids, and the bloom, which contains yeasts which can be used for fermentation.
How is exposure to oxygen reduced during winemaking?
Grapes may be picked at night and kept chilled; antioxidants such as sulfur dioxide maybe used, and wine may be matured in an airtight container such as stainless steel.
Wine made oxidatively may be matured in oak vessels; 225 barriques allow more oxygen exposure than larger barrels.
What does sulfur dioxide do in winemaking?
Protects the grape juice against the effects of oxygen and acts as an antiseptic, limiting unwanted bacterial activity.
What are the most important considerations when using oak for maturation?
Types of oak (French, American, Hungarian) have different characteristics.
Size - smaller barrels impart more oak than larger barrels.
Age - new barrels impart flavor whereas older barrels eventually impart only oxygen.
What are alternatives to oak aging?
Inert vessels such as concrete and stainless steel (easy to clean, better temperature control)
Oak chips or staves (less expensive)
What happens when grapes arrive at the winery?
They receive their first dose of SO2 and are sorted on a sorting table.
What two winemaking steps are optional before pressing?
Destemming (unnecessary if grapes are machine harvested) and Crushing (liberates free-run juice)
What are two types of presses and when does pressing occur?
Basket and bladder (pneumonic) press.
White wine is pressed prior to fermentation; red wine is pressed after.
What are the most common adjustments in winemaking?
The addition of RCGM or chaptalization to adjust sugar; acidification or deacidification; these methods are not allowed in some regions.
What is the name of the yeast used in fermentation?
Saccharomyces Cerevisiae
How can a winemaker halt fermentation?
By sterile filtering, temporary halting by chilling wine to 5 degree or lower, or killing them with SO2 or neutral grape spirit.
What two types of yeast must a winemaker choose between?
Ambient and cultured.
In general, what effect does fermentation at high verses low temperatures have?
Lower temperature preserve floral aromas and bring out the fruitiness of the wine; high temperatures are required for color and tannin extraction.
What are the constituents of wine?
Water 70-90% Ethanol 8-22% Sugars .1-20% Tannins up to .4% Acids .3-1% Compounds .2%
What is Malolactic Fermentation?
Not a fermentation, but a bacteria that converts tart malic acid to softer lactic acid, typically after fermentation. It can be encouraged or prevented by raising or lowering the temperature, and through the absence or use of SO2.
What are lees?
Dead yeast cells and other particles that fall to the bottom of the vessel. Gross lees are generally removed right away, but a winemaker may choose to age a white sur lies to impart a biscuity, brioche quality to the wine.
What are three reasons a winemaker might blend her wine?
Balance, consistency and style.
How might a wine be clarified?
Sedimentation - allowing the large particles to fall to the bottom of a vessel by gravity.
Racking - pumping the wine from one container to another, leaving the sediment behind.
Fining - optional, adding a fining agent to which particles in the wine will bind, in order to be removed by filtration.
Filtration - depth filtration for larger particles and surface filtration for smaller ones. Also optional.
Why might a wine undergo stabilization?
To prevent the later development of tartrate crystals (wine diamonds) by chilling the wine (cold stabilization).
To prevent microbiological activity (sterile filtration)
To prevent oxidation (topping up with SO2)
What are three types of wine closures?
Cork, synthetic cork, stelvin or screw caps
What qualities allow a wine to mature and improve in bottle?
Acid, tannin or sugar and concentration of flavor.
At what temperature does white wine fermentation take place?
12-22 degrees C
What choices must be make in white winemaking?
skin contract, clarity, fermentation temperature and vessel, MLF, lees, blending, clarification and stabilization
Compare the production of an inexpensive white wine, an aromatic wine and a premium wine.
An inexpensive white wine will be made from a neutral wine such as pinot grigio or chardonnay, protected from oxygen, destemmed and crushed, acidified, highly clarified, fermented in stainless steel, possibly flavored with oak staves/chips, often fermented to dryness, then sweetened with unfermented grape juice, stabilized, clarified, and topped up with SO2.
Aromatic grapes will be handled carefully with SO2 levels monitored; gentle clarification; cold fermentation in inert vessels to preserve fruit and floral aromas; little post-fermentation treatment.
Premium Chardonnay or Pinot Gris will also be handled carefully with SO2 levels monitored, gentle clarification; stainless steel, old oak or new oak may all be used for fermentation or maturation; for Chardonnay, MLF may be encouraged as well as lees aging.
