4/5. Winemaking Flashcards
Why is SO2 (Sulfur Dioxide) is added to grape?
Inhibit wild yeast fermentation, slow growth of spoilage bacteria, prevent juice from browning, prevent oxidation, break down pectin (which allows particulate matter to drop out of solution more quickly) [mnemonic: YBBOP]
What are 3 ways to reduce wine’s exposure to oxygen?
use of sulfur dioxide, picking grapes in cool night air, airtight wine making equipment. [mneumonic: NES]
What is the time limit of storing wines in small barrels?
two years (due to risk of excess oxidation)
Name 3 wines that are deliberately oxidized.
Oloroso Sherry, Tawny Port, Rutherglen Muscat
What is largest component of pulp?
water
What is the second largest component of pulp?
sugar
What acids are found in the pulp?
mainly tartaric acid, also malic acid
What are the main components of grape skins?
tannins, flavor compounds, color compounds
How does the harvesting method affect the use of stems in winemaking?
stems are only present if grapes are hand-harvested
What parts of the grape contribute to tannin?
skin, stems and pips
What part of the grape contains bitter oils?
pips
What weight of grapes is required for 750 ml of wine?
one kilogram
What is the bloom of the grape?
waxy surface that covers the skin and contains natural yeasts
What are the 5 main parts of the grape?
skin, pulp, pips, stems and bloom
What are the 4 main steps in grape processing?
reception, destemming, crushing, pressing
What process creates the must?
pressing
What process creates the free run juice?
crushing
What is viniculture?
winemaking [mneumonic: N>wine]; the science, study and production of grapes specifically for wine making
Define must weight.
Must weight is a measure of the amount of sugar in grape juice (must), and hence indicates the amount of alcohol that could be produced
When is sugar added to must during chaptalization?
prior to fermentation
What is chaptalization?
the process of adding sugar to unfermented grape must in order to increase the final alcohol content
In Champagne production when is sugar added?
In Champagne production, measured quantities of sugar, wine, and sometimes Brandy are added AFTER fermentation and prior to corking in a process known as dosage. Chapitalization is sometimes also used before fermentation.
How is de-acidification accomplished? where is this most often done?
addition of potassium bicarbonate (or calcium carbonate and calcium tartrate-malate); more common in cooler climate regions
How is acidification accomplished?
addition of tartaric acid in powder form
What are the 3 general methods for making sweet wines?
Concentrate sugars, interrupt fermentation, add a sweetening component
Name 4 specific methods for concentrating sugars?
Noble rot, drying grapes on the vine (passerillage,) drying grapes after picking (passito,) freezing grapes on the vine (Eiswein)
Name 3 specific methods for interrupting fermentation?
addition of grape spirit (fortification), adding SO2, chilling the must and filtering
Name 4 essential processes in red wine production.
crush, alcoholic fermentation, drain, mlf
Name 3 essential processes in white wine production.
press, alcoholic fermentation, rack off gross lees
Name 4 methods of extraction during red wine fermentation.
pump over, punch down, rack and return, rotary fermentation
What is the timing relationship of fining and tartrate stablitization?
Fining must occur before tartrate stabilization (unstable colloids removed by fining may prevent tartrate crystal formation)
What are the most common types of depth filtration?
Kieselguhr (a type of earth) and sheets made of cellulose fiber
Name two fining agents.
egg white and bentonite
What is bentonite?
fining agent made from volcanic clay
During the process of semi-carbonic maceration, what is the difference between the free-run wine and press wine?
free run wine has been fermented by (wild) yeasts and press wine was enzymatically fermented (intraberry).
What is the 3 different types and the order for fermentations in semi-carbonic maceration?
yeast fermentation (free-run wine), enzymatic fermentation (press wine), yeast fermentation of blended wines, malolactic fermentation
