How Wine Is Made Flashcards
Who was the microbiologist who linked sugar’s conversion to alcohol to the living organisms called yeasts?
Louis Pasteur
What year did we finally discover that yeasts were responsible for fermentation?
1850s
The big difference between red and white fermentation wine is this:
For red wine, the juice is fermented WITH the red grape skins.
What two solvents leach out the reddish-purple color pigments from the skins tinting the surrounding wine during red wine fermentation?
Heat and alcohol
Two reasons we don’t ferment white wine with their skins on
- Add unneeded color
2. add unwanted tannin
What is the machine that removes stems from grape bunches called?
a crusher-destemmer
What is usually the deciding factor for keeping or removing stems from the grapes before they’re crushed during red wine making?
The naturally occurring tannin level in the grape variety being used. For example, cabernet sauvignon (high tannin skins) will not be pressed with stems. Grenache (low tannin skins), will be pressed with stems.
The soupy mass of crushed grapes, juice, skins, pulp, seeds, and possibly stems is called the _______
Must
Two major advantages of using stainless steel or concrete over wooden barrels
- Temperature control
2. Way easier to clean
What is cold soaking, and when during the winemaking process can it be done?
Before fermentation begins, the winemaker can choose to cool down the tank and let the juice “cold soak” for a few days or days. The skins will slowly and gently release small amounts of tannin, aroma, and flavor.
What is the desired outcome with cold soaking?
To make the wine a bit more intense than it otherwise would have been.
Does slower or faster fermentation produces more complex and aromatic wines
Slower
During fermentation, a cap is formed, what is it?
The release of CO2 during fermentation pushes skins to the surface where they form a thick “cap” over the liquid. Unattended they will remain at the surface do to the continual stream of CO2
Why does the cap need to be disturbed during fermentation?
The skins contains the wine’s potential color and tannin, as well as compounds that contribute to aroma and flavor. The more the cap is broken up, pushed apart, and squished down the more skin influence you’ll have on the wine.
Single-celled organisms that belong to the fungus family
Yeasts
What is “punching down”?
Taking a pizza paddle like pole and pushing the skins under the surface of the liquid, breaking up the cap in the process.
What is “pumping over”?
A large hose is run from the bottom of the tank to the top, where the juice is sprayed over the thick mantle of skins and percolated through the cap.
During fermentation, the temperature of the must rises to between ______
60 - 85 F
Fermentation usually takes how long?
From several days to a few weeks
At what concentration of alcohol will yeasts die?
16.5%
Near the end of fermentation, nearly all wines go through a months’ long transformation called ________ . This process is crucial to the wine’s softness and microbial stability.
Malolactic Fermentation
The act of letting the wine (after fermentation) sit on skins for several or more hours, even days.
Post-fermentation maceration, or extended maceration
What is free run?
Approximately 60-70% of the available juice within the grape berry, the free-run juice, can be released by the crushing process and doesn’t require the use of the press.
What is first press?
The remaining 30-40% that comes from pressing can have higher pH levels, lower titratable acidity, potentially higher volatile acidity and higher phenolics than the free-run juice
What is racking?
The process of allowing solids to settle to the bottom of the vat or barrel, then pouring or drawing the clear wine off. It also aerates the wine, helping it mature.
What does fining remove from wine?
Fining removes excess tannin, balancing a wine. It can also clarify minute solids such as unstable proteins
How does fining work?
The coagulant is stirred into the wine and binds to the tannins, the bound molecules re too heavy to remain in suspension and fall to the bottom of the vat/barrel
What are fining agents, give three examples.
Protein coagulants; egg whites, gelatin, isinglass
What makes fining agents different from one another?
Each fining agent is made up of different-size protein molecules that attach themselves to different things in the wine.
What fining agent is used widely in Bordeaux, and if believed to be best at pulling out excessive tannin?
Egg whites
What fining agent pulls out so many things, that is can leave a wine stripped down and neutral? What would cause a winemaker to use it?
Activated carbon (derived from charcoal). It will be used when smoke-taint has occurred, its common in areas susceptible to forest fires.
Two benefits of filtering wine?
- Stabilizes the wine (microbiologically)
2. Removes unwanted particles
The greatest red wines in the world always experience both _____ and _____ aging.
Barrel (oxidative) and bottle (reductive)
A large cylinder in the center of which a pliable air tube is suspended. It is inflated with air, and slowly pushes the grapes against the fine screen inside that machine.
Bladder-press
Red wine vs white wine fermentation temperatures
50-65 (white), and 75-85 (red)
What bacteria carries out malolactic fermentation?
Oenococcus Oeni
Malolactic fermentation chemical process
Malic acid (tart mouthfeel) is converted into lactic acid (soft mouthfeel), and the byproduct diacetyl (molecule that makes cutter taste buttery) is produced.
What is diacetyl?
The byproduct of malolactic fermentation, the molecule that makes butter taste buttery.
What is the goal of malolactic fermentation?
Change the way the wine feels on the palate
What does sur lie mean?
literally “on the spent yeast cells”, its the act of leaving the wine in its vat/barrel with dead yeast cells. Also called on lees.
Why would you let white wine rest on lees?
It adds a slightly richer texture and sometimes more complexity to the wine.
What is cold stabilization, what is its purpose?
Quickly chilling wine down to the point slightly above freezing for a period of several days in order to shock the wine just enough for tartaric acid to precipitate out of the wine in the form of solid snowflake-like crystals.
Oak wood is composed of several classes of complex chemical compounds, which leave their mark on_____
virtually every aspect of a wine’s character
The most noticeable affect oak has on wine is imparted through _______ .
phenols (tannins), which can impart vanilla-like flavors, notes of tea and tobacco, and impression of sweetness.
As far as wine is concerned, oak barrels are ____ to the perfect degree. Both ____ and _____ can evaporate.
Porous, alcohol, water.
What are the three main types of oak used in winemaking
Quercus alba (American), Quercus Robur (French), and Quercus Sessiliflora (French).
French oak vs. American oak
American oak is heavier, denser, and less porous. French oak tends to be less tannic and have more pronounced vanilla and coconut flavor. French oak is more subtle in terms of flavor, more tannic, and allows for greater oxidation.
New barrels vs. second use barrels
New barrels have the strongest impact on a wine’s flavor and aroma. Second use barrels have considerably less impact.
When making off-dry or sweet wine, grapes with very high sugar content are used. Name four ways grapes can be made to have VERY high sugar content.
- Picked when their sugar content is very high
- Picked, laid out on mats, and allowed to raisinate, thereby concentrating the sugar
- Permitted to freeze on the vine so that the water can be separated from the sugary juice
- Attacked by botrytis cinera (noble rot), which consumes the water within the grapes.
What is noble rot, where is it famously utilized?
Botrytis cinera, French Sauternes.
When making off-dry wines, fermentation can be stopped by adding what to the wine?
SO2, it kills yeasts before they have converted all the sugar into alcohol.
What is chaptalization?
Adding sugar to a low-alcohol wine before and/or during fermentation so that the yeasts will have more sugar to convert into alcohol. The goal is not to make wine sweeter, but more alcoholic.
Who is chaptalization named after?
Jean-Antoine Chaptal, minister of agriculture under Napoleon, who first sanctioned the process.
