alcoholic fermentation
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COMENIUS EUROPEAN PROJECT. ALCOHOLIC FERMENTATION. IPSIA “Emilio Cavazza” - POMEZIA. The Alcoholic Fermentation. Fermentation Process Must is not oxidized. Bacteria can grow and proliferate. - PowerPoint PPT PresentationTRANSCRIPT
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 :
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