* Wine is the oldest fermented drink known.The first treatise of oenology date back to 4000 years.We have began to understand the mecanisms of transformation of grapes ' juice in wine thanks to PASTEUR's works.Wine is not a simple chemical product it is made of about 500 constituants in different proportions. In France,we express the totale wine's acidity by its teneur in grammes of sulphuric acid (H₂SO₄) in a liter of wine.Acidity of wine is the result of a different acids melting (tartaric, succinic, ethanoic, malic, lactic...).The totale concentration in acide of wine is determined by dosage.To evalue wine acidity, we can use a chimical colored indicator : bromothymol blue (BBT). It changes of color in fonction of pH of the solution  in which it is. It is yellow when the solution is acid and becomes blue when the solution is basic.

EXAMPLE:

 * We need 11ml of soud in 20ml of wine to obtain a dark blue coloration so the solution becomes basic. It corresponds at 2,7 gr of sulfuric acide.These value is inferior to the imposed minimal value Which is 2,94 gr of sulfuric acid by a liter of wine marketed.

CONCLUSION:

 ** It is important to evalue the wine acidity  because it can favorise the apparition of damages or  provoke a bad conservation of wine.
 
 
 

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