COMENIUS EUROPEAN PROJECT

IPSIA “Emilio Cavazza” - POMEZIA

ALCOHOLIC FERMENTATION

The Alcoholic Fermentation

Alcoholic fermentation is the reaction needed to produce wine.

It can change,

Sugar to alcohol and CO2…

Its taste must have the organoleptic quality of grape.

All the process is anaerobic.  

 

Fermentation Process

Must is not oxidized. Bacteria can grow and proliferate.

Fermentation must be done by a given lapse of time and at a given

temperature. It is also necessary to control density.

By these values it is possible to know the quality of the product.

 

The tubs serve to fermentation of red wine to soak the peels.

Temperature will be higher to give greatest density to the wine.

THE TUBS

Malolactic Fermentation (MLF) comes from:

1. pH2. Centigrades

3. Sulfuric4. Aeration5. Alcohol

MLF Process

MLF can be generally activated by lyophilized bacteria to be solved in mineral water.

The wine produced must be kept at a temperature of 24 degrees for 24 hours. After, it will be added to and mixed

up with the compound to be fermented. The fermentation lock is set on the tub, and temperature is

kept at 20-22 degrees for a week. The following factors must be kept under control: cleanliness of the containers used to activate the

fermentation process; the containers‘ temperature, as MLF does not generate heat;

CO2 , whose presence can be easily tested by tasting.

Malolactic Fermentation

San Giovese wine (for example):

Red Wine Reference valuespH  3,36 3,0 - 3,5

ALCOHOLIC DEGREE % vol 12,70 10,0-13,0

Overall acidity g/l Tartaric acid

8,00 4,5 - 7,0

Gross volatile acidity g/l Acetic

acid 0,39 0,20 - 0,70

Flat acidity g/l Tartaric

acid7,50 4.5 - 7.0

Sulphurous anhydride unlocks mg/l 14,00 15 - 50

Overall sulphurous anhydride mg/l 33,00 40 - 150

Glucose and fructose g/l 0,20  

L-malic acid g/l 2,00   Overall Polifenoli   52,80  

Industrial productionIn industrial production, before bottling operations,

chemical tests are performed on wine in order to control the amount of acidity, sulphur dioxide, copper, iron,

proteins, bacteria and yeasts. These are factors that can affect the conservation and biological stability of wine.

 These elements can be kept under control by filtration. Filtering equipment can be found at specialized shops.

 Chemical fermentation process

 Fermentation process consists of two stages.

  First stage: the yeast separates complex sugars;

Second stage: ethyl alcohol generates from simple sugars.

THE FIRST REACTION IS:

C12H22O11 + H2O → C6H12O6 + C6H12O6

In the second phase glycolysis occurs. The molecule of glucose is divided into

two molecules of pyruvic acid, and through a series of enzymatic

reactions ethanol is produced.

C6H12O6 → 2 C2H5OH + 2 CO2

THE FINAL REACTION IS :

THANK YOU FOR YOUR ATTENTION