Maria DOLORES HUERTA*, Maria ROSARIO SALINAS FERNANDEZ**,
et TAISIR MASOUD MUSA*
*Departamento de Nutrición y Bromatología. Facultad de Farmacia
Universidad de Alcalá de Henares, Km. 33.600 Ctra, Barcelona, 28871 Alcalá de Henares, Madrid (España).
**Cátedra de Química Agrícola, ETSI Agrónomos, Universidad de Castilla-La Mancha, Campus Universitario, 02071 Albacete (España).

Abstract : This work constitute a first approximation to study the relation between the value of the titrable acidity at different pH and the colour intensity of wines. The organic acids from wines treated with NaOH are weak acids, for this reason the neutralisation with a strong alkali solution, it should give pH values greater than 7. We have studied a new parameter based on the difference between pH 8.2 (stablised by the Association of Official Analytical Chemists) and pH 7.0 (stablised by the Office Internationl de la Vigne et du Vin). the mentioned parameter (AT8,2-AT7,0) has been used to find a possible differentiation between wines according to colour.
Eighty eighth wines (white, red and rose) belonging to the three district making up the&laqno; Vinos of Madrid » Origin were analysed. The values of this new parameter are similar for white and rose wines but considerably differences were observed for the red type. A linear correlation was obtained between the AT8.2-AT7.0 parameter and the colour intensity from red wines. Discriminant analysis were applied to this parameter in order to classify the wines according to their colour. A correct classification of 71.43 p. cent was obtained for the three different types of red wines.

Key words : wine, titrable acidity, colour intensity