Study of the Acidification of Sherry Musts With Gypsum and Tartaric Acid

¹ Technical Dept., Osborne & Cia., S.A., Fernan Caballero, 3, 11500 El Puerto de Santa Maria, Spain.

Must acidification is a necessary operation in hot regions due to the low natural acid content of the grapes grown there. Tartaric acid is what is most usually used for this purpose. Using gypsum (CaSO₄ · 2H₂O) allows the amount of tartaric acid needed to reach a given pH to be reduced. This paper is a study of the acidification of musts produced in Sherry area (Southern Spain) to a pH of 3.25 with tartaric acid alone and tartaric acid acting together with 2 g/L of gypsum. Using gypsum causes a reduction in must pH of approximately 0.2 units and allows the tartaric acid dosage to be cut down by 1.5 to 2.5 g/L. The concentration of sulfates in the fermented wine lies below 2.5 g/L (the maximum authorized by the European Community), and the calcium concentration is 130 mg/L. Both levels are compatible with a correct winemaking. The acid buffering power of the wine and the alkalinity of the ash are reduced by the use of gypsum, which makes later acidification easier. Other wine component levels are not affected.

Key words: gypsum, tartaric acid, sherry must, must acidification

Submitted on January 18, 1993