Winemaking Flashcards
What does the Skin of a grape contain?
Colour
Tannin
Flavour
What do the Pips and Stems of a grape contain?
High levels of Tannin
What is ‘Bloom’ and what does it consist of?
Bloom is the waxy surface covering the skin of the grape
It contains yeast and bacteria used to ferment wine
What is the Grape Reception and what are they treated with here it not first at picking time?
Where the grapes are received into the winery.
They are then treated with Sulphur Dioxide if not at picking
What two factors are optional are the Grape Reception?
Destemming and Crushing
What is an easy way to destem grapes before entering the winery?
Machine Harvesting
What happens if you want to remove grape stems inside the winery and what else can be done together with this?
A machine can be used which can also crush the grapes. It breaks the skin of the grapes
What the advantages and disadvantages of crushing the grapes?
Advantages -
Liberates a quantity of juice known as Free Run juice
Disadvantages -
Can put pips at risk of being damaged and release a bitter oil
Which two presses can be used to crush grapes?
Pneumatic
Horizontal
Referring to Adjustments in wine, what is Enrichment?
Adding sugar or removing water to raise alcohol level
Referring to Adjustments in wine, what is Acidification?
Carried out by the addition of tartaric acid in a powder form
Referring the Adjustments, what is De-Acidification?
Neutralising grape acid by adding chemicals such as Potassium Bicarbonate
Referring to Adjustments, what is Tannin?
Tannin can be increased by adding tannin powder or oak
What does Fermentation mean?
A chemical reaction brought about by action of yeast or bacteria
What is Alcoholic Fermentation?
The conversion of sugar and carbon dioxide into alcohol through the action of yeast
What happens if the temperature is below 5 degrees during alcoholic fermentation?
It will not start fermenting until above this
When does Alcoholic Fermentation stop and what is the average temperature of this?
When all sugar has been consumed or
When alcohol levels are so high that it kills the yeast
Usually stops at a temp of 15%Abv
What is another reason for Alcoholic Fermentation to stop?
If the yeast runs out of nutrients
What two things can a winemaker do to stop Alcoholic Fermentation?
Add SO2 to kill yeast
Chilling the must and filtering out the yeast
What is the most important yeast used and why?
Saccharomyces Cerevisiae
It can tolerate high levels of alcohol and SO2
It can create attractive flavours in wine
What can reduce complexity in the wine after Alcoholic Fermentation?
Yeast Strain
What other yeast can produce excellent flavours in a wine?
Ambient yeast
What is Malolactic Fermentation?
Carried out once alcoholic fermentation is done and done using lactic bacteria.
Converts Malic acids into Lactic acids
It can soften wines and reduces acidity
Do all red wines undergo MLF (malolactic fermentation)?
Yes
What flavours can come from Malolactic fermentation?
Butter
Hazelnut
What is the process of Pre-Fermentation Extraction?
Grapes can be left after de stemming and crushing to macerate for a period of time at a low temperature.
What are the advantages of Pre-Fermentation extraction?
Allows for a greater colour
Allows for greater fruit aromas
What does the Pulp of a grape contain?
Water
Sugar
Acids (tartaric and some malic)
Why is the presence of skins during fermentation for red wine impractical?
It’s nearly impossible to maintain contact between the skins and juices
What temperate is reached for red wine fermentation and at what temperature will it cease to continue fermenting?
Usually reaches between 30-32 degrees.
Will cease to continue at 35-38 degrees.
Why will temperatures vary in red wine when fermenting?
Depends on the style of wine wanted
Grape variety
Region
What happens if the fermenting period of red wine is left alone and what is this called?
It will produce a thick mass of pulp and skins on the surface.
It is called ‘The Cap’.
What happens if ‘The Cap’ is left to float on the surface during fermentation?
Juice won’t be able to extract much colour.
What is it called when you draw wine from the bottom of a vat to the top?
Pumping over
What are the 3 advantages of ‘Pumping Over’?
Breaks up the cap
Circulates heat
Oxygenates the juice
What is it called when mechanical paddles push down the cap during fermentation?
Punching down
What is ‘Rack and return’?
It is when the juice is drained from the fermenting barrel, leaving the cap behind.
It is then pumped back over the cap.
What is rack and return very useful for?
Dissipating heat
