Fermentation of wine-Ch. 5 Flashcards
If left unattended what will happen to grapes right after harvest?
(1) Degrade/oxidize (2) Concentrate their sugars/raisinize (3) broken grapes start to ferment
What can be done to protect the grapes immediately after harvest?
(1) Give sulfur (2) keep the grapes cool
What 2 things does sulfur do to protect the grapes?
(1) Combines with 02 to form sulfur dioxide, (2) sulfur dioxide inhibits the growth of yest and bacteria
What is the term for the process that happens to the grapes right after harvest which removes leaves and under-ripe or damaged grapes?
Sorting
What is cold soak? and what is its purpose? Is it mostly done for red wine or white?
After pressing grape must is allowed to macerate on the skins of the grapes for a short period of time….this allows the must to extract the tannins/color/aromas….Mainly done for red wine but good for some white aromatic wines.
What free-run juice?
The must that happens before pressing; from crushing or just the opening of skins from the weight of the grapes on top of each other.
What can be done with the free-run must and the press must?
They can be blended…..Free-run gives fruitiness, aromas, balance while the Press must gives tannin, body, complexity….Usually blended in a ration of free-run-to-press of 9-1.
What is the name of the modernized press machines? and what is its benefit?
Bladder presses…It gently presses the must out of the grape without crushing the seeds or open the skin cells.
What is the term for the remaining paste cake of dry grape skins and seeds after the final press? and what is it used for?
Pomace….(1) used as composte, (2) used to make promac brandies called Marc or Grappa.
What is the term for grape juice destined for fermentation?
Must
What are the 5 steps involved in the pre-fermentation stage?
(1) Sorting, (2) crushing/destemming, (3) Pressing, (4) Must adjustment, (5) juice setling/deborbage.
What are 2 classic exampies or must adjustment?
(1) Acidification, (2) Chaptalization
Why would acitification be done? and what is used?
In certain vintages where it was too hot and did not produce enough acid….Tartaric acid.
Why would chaptalization be done? What is its purpose?
In certain vintages where it was too cold to produce enough sugar…..It is only added to inc. the alcohol level.
What are the 2 types of yeast used to make fermentation?
Wild yeast and Commercial yeast.
What is the term for injecting commercial yeast into the must to start fermentation?
Innoculation
What is the commercial yeast called?
Saccharomyces cerevisiae
What is the term for when the yeast prematurely stops fermenting? and give an example of what causes it?
Stuck fermentation….Too HIGH temperatures during fermentation, i.e. >100F.
What is the optimal temperature for fermentation? and what does it allow to retain?
50-60F…..The fruit and floral aromas.
Name 2 reasons yeast will stop fermenting wine appropriately?
(1) When it has consumed all the sugars, (2) When it has reached an ABV of 14%
In is the term for the 2nd fermentation that takes place in order to soften the acidity level in the wine?
Malolactic fermentation
What type of bacteria initiates MLF? and it converts what to what?
Lactic bacteria…..malic acid to lactic acid
What does MLF do to wine?
It turns the sharp malic acid of tart, green apples to lactic acid which softens, creamier, buttery
What is the name of the ester that is created through MLF?
Diacetyl