13. General Winemaking

Question 1

What does “Pied de cuve,” mean

Answer 1

“Pied de cuve,” roughly translated as “foot of the tank,” is a winemaking technique using a small, pre-fermented batch of grape juice to inoculate a larger batch, promoting fermentation with wild yeasts from the vineyard.

Question 2

What is plastering method (from Jerez Spain)? and how does it aid acidification?

Answer 2

The “plastering” method, involved adding calcium sulfate (gypsum) to wine must to increase acidity by precipitating out calcium tartrate and leaving the more acidic potassium bisulfate

Question 3

What is YAN
Yeast Assimilable Nitrogen?

Answer 3

YAN is a measurement and sum of both natural ammonia and free amino acids

Question 4

When is the yeast strain Saccharomyces Bayanus used

Answer 4

• Restarting fermenants
  
  • resistant to high alcohol and SO2
  • yeast particularly associated with the flor in sherry production

Question 5

What are yeast metabolites?

Answer 5

Yeast metabolites are formed as yeast metabolizes sugars and other nutrients during fermentation.
Can be simple or complex compounds
Ei. Esters, Ethanol, Carbon Dioxide
glycerol, acetic acid

Question 6

Define “yeast microflora”

Answer 6

“yeast microflora” refers to the diverse community of yeast species naturally present on grapes and in the grape juice (must) that can contribute to the fermentation process.
ei. influencing flavours/aromas

Question 7

Are ambient or commercial yeasts considered ‘natural’?

Answer 7

All wine yeasts are natural since no genetically modified organisms are allowed in winemaking

Question 8

What is the group of fungi of which yeast in general belongs to

Answer 8

Ascomycetes

Question 9

What happens when yeast switch to an anerobic mode:?

Answer 9

Their metabolism slows down and they yield alcohol instead of an aqueous effluent

Question 10

What would be the result if yeast had unlimited access to oxygen?

Answer 10

The yeast would not produce alcohol

Question 11

What is a structural isomer
give an example

Answer 11

a molecule that has the same molecular formula as another molecule but with a different connectivity of atoms
ei. glucose and fructose

Question 12

Give three examples of winemaking options when using ambient yeast during fermentation;

Answer 12

• fully spontaneous (laissez faire)
• Can add a pied du Cuve (yeast starter)
• grape are picked early, crushed, start to ferment
• do early phase of fermentation with wild yeast then add cultured