Fermentation

Question 1

What is alcoholic fermentation?

Answer 1

It’s the primary fermentation where sugars of the berries are converted into ethanol and CO2, it’s done by yeasts

Question 2

Where do these yeasts for fermentation come from ?

Answer 2

From the grapes, additional yeasts on the market and yeasts in the cellar

Question 3

What is the main yeast used in winemaking

Answer 3

Saccharomyces cerevisiae

Question 4

Whenever we refer to fermentation we refer to it in being dry, why is that ?

Answer 4

The main yeast Saccharomyces cerevisiae has a very high ethanol tolerance and can therefore ferment completely, leaving no sugars behind

Question 5

What is the difference between wine, yeast and wild yeast?

Answer 5

Wine yeast is the specific general yeast called Saccharomyces cerevisiae.
Wild yeasts are all the yeasts on the grapes or in the cellar or non-Sacchromyces yeasts. An example is Kloeckera apiculata
These yeasts or spontaneous and many of them are not that ethanol tolerant, and therefore dies off before the end of fermentation. The yeasts or non-reliable and causes of or odours.

Question 6

What is Active dry wine yeast

Answer 6

It is a yeast that is selected for specific attributes. It causes less bad aromas, and it is efficient in sugar conversion, and it is pretty predictable when it comes to fermentations

Question 7

Why are commercial yeasts used?

Question 8

What are the different types of fermentation vessels?

Answer 8

Stainless steel tanks: they are easy to regulate temperature and clean and they are also cost-effective.
Barrels
Clay Amphoras
Wooden open tanks
The type of fermentation vessel depends on the style of the wine.

Question 9

What are the different periods of yeast growth?

Answer 9

Lag period: acclimatises
Exponential growth: 50 to 70% of sugar converted
Stationary phase: nutrients reduced, alcohol levels increased, stress.
Death: severe nutrients and sugar shortage, yeasts poisoned.

Question 10

What sugar does S. cerevisiae prefer the most?

Answer 10

It prefers glucose over fructose

Question 11

What should be kept in mind while managing the fermentation process?

Answer 11

Beware of CO2 and avoid high temperatures as this may cause bacterial growth, loss of aroma, lower alcohol production, and the yeast becomes sluggish

Question 12

At what temp is white wine fermented

Answer 12

12-16 C

Question 13

At which temp is red wine fermented?

Answer 13

25-30C