Chapters 7-10 Winemaking Flashcards
What 2 acids are present in the pulp of a grape?
Tartaric acid
Malic acid
What methods are used in a winery to limit oxidation during the winemaking process?
Antioxidants - sulfur dioxide
Night picking - effect of O2 is reduced as chemical reactions occur slower in cool temperatures
Grapes chilled until they reach the winery
Winery equipment filled with CO2 or nitrogen before use
What name is given to the process of winemaking with no oxidation?
Anaerobic or protective winemaking
What vessels are used to protect wine from oxidation during maturation?
Stainless steel inert, airtight tanks or vats
Cement tanks lined with epoxy resin
What changes occur to red wines that are matured in oak?
Small amounts of oxidation Softer tannins Primary fruit flavours fade Tertiary flavours (leather, earth) develop Red wines become paler
What are 3 pronounced tertiary flavours (normally seen in sherry or port) that are assocoated with oxidation?
Caramel
Toffee
Nuts
What has happened to a wine that is ‘oxidised’?
Too much exposure to oxygen
Fresh fruit flavours are lost and wine smells stale.
In an extreme case, bacteria will use oxygen to change the wine into vinegar
What 2 purposes is sulfur dioxide used for in a winery?
Antioxidant
Antiseptic
What effect do oak tannins have on a wine?
Oak tannins give more structure to both red and white wines, increasing textural complexity
What 4 aromas and flavours can oak maturation add to a wine
Toast
Vanilla
Smoke
Cloves
What 4 features of an oak barrel impact the effect it will have on a wine?
Species/origin of oak (European vs USA)
Size
Production of barrel - toasting
Age - how many times its been used
What are 2 alternatives to oak barrels that will impart oak aromas and tannins?
Oak planks (staves) Oak chips
As freshly picked grapes arrive at the winery, what is the first step in grape processing?
A first dose of sulfur dioxide is added
If a premium wine, they will be individually checked to eliminate unripe or rotten grapes
What will grape seeds add to a wine if inadvertently crushed?
Bitter oils and tannins
Unpleasantly astringent and bitter
What is ‘must’?
Grape juice
What can be added to wine to increase sugar levels?
Rectified Concentrated Grape Must (RCGM)
What is chaptalisation?
The addition of sugar from sources other than grapes eg. sugar beet
What can be added to wine to increase acid levels?
Tartaric acid in powder form
What can be added to wine to decrease acid levels?
Alkali
What is the name of the yeast that is responsible for the majority of wine fermentation?
Saccharomyces cerevisiae
Sugar + yeast = ?
Alcohol + CO2 + heat + flavour compounds
Alcohol fermentation will not start if the temperature is below what?
5°C
At what maximum temperature will alcohol fermentation stop?
35°C
What are 3 ways of either killing or removing yeast in order to stop fermentation?
Adding sulfur dioxide
Adding grape spirit
Chilling below 5°C and filtering
What are 2 ways in which a winemaker can control fermentation?
Choice of yeast
Temperature management
What is malolactic fermentation (MLF)?
Occurs after alcohol fermentation finished
Lactic acid bacteria + malic grape acid = lactic acid
What effect does MLF have on wine?
Softens and reduces acidity
Creating buttery flavours
How does a winemaker encourage MLF?
After alcohol fermentation
Increases the temperature of the wine
Does not add sulfur dioxide