Still Wine Production Flashcards
What are two other terms for winemaking?
Vinification or enology.
What is the greatest priority after harvest and why?
To begin the winemaking process to prevent oxidation.
How is oxidation prevented after harvest?
Keep the grapes cool and covered; also potentially the use of sulfur.
What is the pre-fermentation process known as?
The “crush,” a term which is used to decide the actual crushing of the grapes as well as everything that gets the juice ready for fermentation
What role does sulfur place in the winemaking process?
Sulfur combines with oxygen to form SO2, which inhibits the growth of yeast and bacteria, as prevents the juice from oxidzing.
What’s the first step of pre-fermentation?
Usually a visit to the sorting table, were damaged or undesirable grapes are removed; can be done by hand or partially mechanized.
What step of pre-fermentation is skipped by some producers?
Crushing and destemming, as some producers opt for whole cluster pressing.
How is crushing different than pressing?
During crushing, the skins as broken and the juice is allowed to run, but no pressure is applied.
In white wine production, what is generally avoided, and what is a notable exception?
Contact between the skins and juice are minimized to avoid coloration, however some aromatic varieties benefit from a short period of maceration to extract aromas and phenolics. This is normally done while chilled, hence the term “cold soak” and for no more than 24 hours.
What is “free run juice”?
The juice that runs out the grapes immediately in the pressing stage. Free run juice is often kept separate from later press juice and used for the producer’s best wines.
What type of press is mostly used today?
Bladder, or pneumatic press, which expand and contract, applying much gentler presser on the grapes, but with more flexibility, allowing more juice to be extracted while avoiding the negative consequences of too much pressure.
What is pomace and what can it be used for?
The cake of dried skins and pips that remains after the final press; it can be plowed back into the vineyard or used to make marc or grappa.
What is “must”?
Grape juice destined for fermentation.
What are the two most common adjustments made to the must.
Acidification and chaptalization.
Acidification is done to correct a poor sugar-acid balance and is normally achieved with tartaric acid. De-acidification can be achieves with potassium or calcium bicarbonate.
Chaptalization is done by adding sugar to the must in order to achieve desired alcohol levels–not to increase sweetness in the final wine.
In the Old World, adjustments such as these are sometimes prohibited.
What is debourbage and what does it accomplish.
Juice setting prior to fermentation–done to allow an adjustment to fully integrate, to allow particles to fall out of suspension, or have time to process additional grapes.
What is fermentation?
Yeast cells attach sugar and break them apart to release energy, some of which is given off as heat. The molecules that remain are ethanol and carbon dioxide.
C6H12O6 + yeast -> 2(C2H5OH) + 2(CO2) + heat
The actual mechanic of fermentation involves about30 chemical reactions, each catalyzed by a specific enzyme in the yeast.
How much of the sugar in the must is typically fully converted in fermentation?
Usually 90% but the rest is broken down into glycerol, succinic/acetic/lactic acid, acetaldehyde, ethyl acetate and methanol.
What vessels are typically used for fermentation?
Often stainless steel tanks, which are inert, airtight, easy to clean and provide easy temperature control. Some white wines are barrel fermented in barriques to add complexity. Large wooden casks and concrete vats are also used in traditional wineries.
How is fermentation usually initiated?
Ambient yeast can often be found in and around the winery, as well as on the grapes themselves, so it is harder to prevent than initiate fermentation. Fermentation can be stopped by the use of sulfur, which is toxic to yeast, as well as refrigeration which stops most biological activity.
What is the name of yeast most commonly used in winemaking?
Saccharomyces Cerevisiae
What is inoculation in winemaking?
Rather than rely on ambient yeast, a winemaking may choose a specific culture yeast and inoculate the must with it to initiate fermentation. The strain of yeast used may have a significant effect on the characteristics of the resulting wine.
What fermentation temperature is ideal to preserve the delicate fruit and floral qualities of the wine?
50-60 degrees
What commonly causes “stuck fermentation”?
Elevated temperature about 100 degrees, which causes the yeast to die.
How long does fermentation last?
Anywhere from a few days to a few weeks?
At what ABV does fermentation usually come to an end?
At 14% ABV, at which point the yeast can no longer survive.
Why might a winemaker intentionally stop fermentation?
To produce a medium-dry or off-dry wine.
What is typical alcohol content of a finished white wine?
12-14% but can be as low as 7%
What is malolactic fermentation?
Not a true fermentation, but a conversion of tart malic acid to milder, creamy malic acid. It can take place during or after primary fermentation.
MLF doesn’t usually initiated on its own and can be prevented with SO2, per the winemaker’s preference.
What gives a wine which has undergone MLF it’s distinctive buttery aromas?
An ester called diacetyl, which is a byproduct of MLF.
What are lees?
The dead yeast particles that fall to the bottom of the vessel after fermentation. The wine can be separated from the lees by a process called racking.
What do sur lie and batonnage mean?
Sur lies is a form of aging, in which the wine is left in contact with the lees for an extended period of time to add complexity, texture and sometimes a sourdough or biscuity aroma. Batonnage refers to the stirring of the lees with a baton, to amplify its effects.
After fermentation is complete, why might it be particularly important to add more sulfur?
To prevent microbial spoilage and browning, but especially in the instance of residual sugar, which could lead to unwanted fermentation in the bottle.
What are four methods of clarification?
racking, filtering, fining, centrifuge
