Chapter 7 - Common Elements in Winemaking and Maturation Flashcards
Name the constituent parts of grapes.
Seeds; Stems; Skins; Bloom; Pulp
What is the Bloom of a grape?
The waxy surface that covers the skins of the grapes and contains yeasts that can be used to ferment the wine.
What is Protective or Anaerobic winemaking?
Techniques in which all efforts are made to keep grapes and juice away from oxygen, including filling airtight winery equipment with either CO2 or nitrogen before they are used for grape processing. Vital to create a wine dominated by primary fruit characteristics.
True or False? Wines that are matured aerobically are stored in wooden vessels that are normally made of oak
True
What can oxygen do during a wine’s maturation?
Since it is not airtight, small amounts of oxygen can make it through and react with the wine. This can help to soften tannins in red wines. Primary fruit flavors will gradually fade and tertiary characters start develop. Color may also change due to the oxygen.
Name two ways SO2 acts in wine making.
It acts as an antioxidant and an antiseptic.
What are some of the aromas and flavors that can be passed on from oak?
Oak tannins give more structure to both red and white wines, increasing their textural complexity. Oak can also give aromas and flavors of toast, vanilla, smoke and cloves.
What are two alternatives to using oak vessels?
Using small oak planks, called staves, or smaller oak chips.
Why should the grape seeds never be crushed?
They can release bitter oils and tannin, and the wine may become unpleasantly astringent and bitter.
When does pressing typically occur?
In the case of white wines, pressing occurs before the start of fermentation; for red wines this typically happens after fermentation.
What is grape juice commonly referred to?
It is referred to as “must”.
What is the must weight?
The level of sugar in the juice.
What is RCGM?
Rectified Concentrated Grape Must - a colorless, odorless syrupy liquid used to increase sugar levels.
What is Chaptalization?
Where sugar from sources other than grapes is added.
How can acid levels be increased?
Acidification is normally carried out by the addition of tartaric acid in powder form.
How can acid levels be decreased?
Excess acid may be neutralized by the addition of an alkali.
What are the by-products of the fermentation of sugar?
Alcohol, CO2, Heat, Flavor compounds
What is the yeast species responsible for the majority of wine fermentation?
Saccharomyces cerevisiae
What is the temperature range where fermentation can happen?
Between 5 and 35 degrees celcius
What are the two important ways in which a winemaker can control the fermentation process?
The choice of yeast and temperature management.
What are two types of yeasts commonly used?
1) Naturally occurring yeasts
2) Commercially available cultured yeasts.
What does fermenting at low temperatures do?
Avoids the loss of the most volatile aromas (often floral) and can encourage the development of fruity flavors in white wines.
Why are higher temperatures needed during fermentation?
Necessary for the extraction of color and tannins from black grape skins.
What is malolactic fermentation?
A secondary fermentation that occurs once the alcoholic fermentation is complete. Converts the tart malic grape acid into the softer lactic acids. It softens and reduces acidity, and can create buttery flavors.
What is referred to as “gross lees”
Dead yeast cells and grape fragments that fall to the bottom of the fermentation or storage vessel.
What are the three primary methods to clarify wine?
Sedimentation; Fining; Filtration
How does Sedimentation work?
It relies on gravity to pull the suspended particles to the bottom of the liquid.
What is Racking?
When wine is gently pumped into a new vessel, leaving the sediment behind. This is a process that is often repeated to continually clarify the wine.
What is Fining?
Adding a fining agent to the wine, a substance that forms bonds with certain wine constituents and causes visible clumps to form. These clumps can then be removed by filtering.
What is Filtration?
A process that physically removes particles from a wine as it is passed through a filter.
What are the two methods of Filtration?
1) Depth Filtration - can also remove gross lees
2) Surface Filtration
What are the three important areas that require stabilization?
1) Tartrate Stability (dealing with tartaric acid crystals)
2) Microbiological Stability (dealing with microorganisms that can spoil wine - yeasts and bacterium)
3) Oxygen Stability (dealing with excess levels of oxygen)
What causes cork taint?
TCA - trichloroanisole
What is an advantage of screw-caps?
By preventing oxygen to enter the bottle, they help preserve the primary aromas and fruit flavors.
