Fermentation & Still Wine (WHITE WINE)Production Flashcards
What is the term for the basic art and science of winemaking?
Enology
How soon after harvest should the process of wine making begin?
As soon as possible
What starts happening to grapes once they are picked?
They start to degrade and become oxidized
If left alone, what happens to unbroken and broken grapes?
Unbroken grapes can become raisins, and broken grapes can begin to ferment in unpredictable ways
To prevent grapes from spoiling, what can winemakers do?
Keep grapes cool and covered, and perhaps use sulfur as a preservative during transport
When using sulfur as a preservative, what happens when it combines with oxygen
It can combine to form sulfur dioxide
What does sulfur dioxide do to preserve grapes?
It inhibits growth of both yeast and bacteria, preventing premature fermentation or spoilage, and prevents juice from oxidizing and turning brown
What is the pre-fermentation part of winemaking often broadly referred to as?
The crush
What is sorting?
When undesirable elements of the harvest including leaves, underripe bunches, damaged fruit, and other debris is removed
What type of machine are sorted grapes sometimes placed into, and what does it do?
A crusher-destemmer, which crushes grapes to release juice while at the same time removing and discarding stems
For the production of white wine, the crusher-destemmer machine is sometimes eliminated, in favor of producing what type of press?
‘Whole-berry’ or ‘whole-cluster’ press
For some white wines where a little contact with skins is encouraged, what does this minimized process called ‘cold soak’ entail?
Juice is chilled with skins still present in order to extract aromas and desirable phenolics
How long does a cold soak generally take?
No more than 24 hours
Much juice from berries is released during transport even prior to a crush. This, which is often reserved for higher quality wines, is called what?
Free run
How might one describe the qualities of free run juice
It is often rich in sugar and low in tannin
What is a bladder press?
Essentially a large air bag which crushes grapes with a great deal of force, but with flexibility
What is the cake of dry compressed skins and seeds (pips) of grapes called?
Pomace
What is often done with pomace when it is not repurposed for other beverages?
It is used for compost in the vineyard
What types of liquors can be produced with pomace?
Marc or grappa
What is must?
Grape juice destined for fermentation
What is must adjustment?
When acid or sugar levels are determined by the winemaker to be insufficient, so adjustments are made to fix either of these problems
What is acidification?
The process of adding acid directly to the must in the case of low acid levels
What type of acid is used in acidification?
Tartaric acid
If necessary, de-acidification can be done using what?
Potassium or calcium bicarbonate
What is chapitalization?
The process in which sugar is cautiously added to the must to improve sugar levels
What is debourbage?
The French term for juice settling
What is juice settling
When the winemaker determines that freshly pressed juice might need to settle for a day or so
What are some reasons that a winemaker may choose to employ juice settling?
In order to allow must adjustments time to fully incorporate with the juice, or to allow solids to further separate out of the juice prior to fermentation, or to have more time to process additional grapes to be pressed into the batch
About how many successive chemical reactions occur during fermentation?
Thirty
What is a simple description of the process of fermentation?
When yeast cells attack sugar molecules, breaking them apart to release energy, some of which is given off as heat
What are the smaller molecules that are left behind after the yeast cells have split apart the sugar?
Ethyl alcohol and carbon dioxide
What is the molecular number for sugar?
C6h12O6
What is the molecular number for alcohol?
C2H5OH
What is the simple formula for fermentation?
C6h12O6 + yeast → 2 (C2H5OH) + 2 (CO2) + heat
About what percent of grape sugars are converted into alcohol during fermentation?
About 90%
What are seven things that sugar that hasn’t been converted into alcohol might become?
Methonol, acetaldehydes, succinic acids, acetic acids, lactic acids, glycerol, and ethyl acetate
What is meant when stainless steel vats are described as inert?
They do not impact the flavor of the wine
What is must innoculation?
Introduction of cultured yeast that gets fermentation off to a quick start, and prevents fermentation from any native yeasts present
Most yeasts used in winemaking are strains of what
Saccharomyces cerevisiae
What is the optimal temperature range for preserving delicate fruit and floral aromas during fermentation?
Between 50 and 60 deg F
Above what temperature during fermentation can yeast die and fermentation stop?
100 deg F
What is it called when temperature levels get too high, killing yeast and stopping fermentation?
Stuck fermentation
About how long can fermentation take place?
Anywhere from several day to several weeks
At what alcohol level can yeast sometimes not be able to survive?
About 14%
What is the typical range of alcohol content for white wines?
Between 12%-14%
What is malolactic fermentation?
Secondary fermentation which can take place during or after alcoholic fermentation that decomposes sharp malic acid and converts it to lactic acid
What happens to wine that undergoes malolactic fermentation (MLF)?
Tart, “green apple”-like characteristics of malic acid are replaced with milder and creamier characteristics of lactic acid
What is diacetyl?
An ester that is a byproduct of MLF that introduces a “buttery” aroma to wine
What are lees?
The sediment of expired yeast cells and other solids that remain after alcoholic fermentation
What is the method of wine being removed quickly from lees?
Racking
What is sur lies aging?
When wine is allowed to age on the lees, imparting a yeasty aroma and creamy texture to the wine
What is it called when lees sediment is stirred back up into the liquid to amplify the effects of sur lies aging?
Lees stirring or Bâtonnage
What is post-fermentation sulfur addition important for?
To decrease the chance of microbial spoilage or browning in wine, and in the case of leftover residual sugar prevent additional fermentation from occuring
What is clarification?
When yeasts and solids are removed from wine to make it more clear
What are four common methods of clarification?
Racking, fining, filtering, centrifuge
What clarification method involves allowing gravity to cause sediments to settle at the bottom, and have juice carefully extracted from above the sediment?
Racking
