Verification of the practical suitability of cation exchangers for lowering the pH value in must and wine

Institute for Viticultureand Oenology, DLR Rheinpfalz, Breitenweg 71, 67435 Neustadt/W, Germany

^* Corresponding author: pascal.wegmann-herr@dlr.rlp.de

Abstract

Due to climate change, grapes are reaching continuously higher levels of technological maturity. However, this also leads to lower acidity levels and higher pH values in musts and wines. Higher pH values would result in higher risk potential regarding undesirable microorganisms, associated with wine faults. Since 2013, cation exchangers have been allowed for acidification. In addition, yeasts of the genus Lachancea releasing lactic acid during fermentation to lower the pH of the wine. In addition to lowering the pH value, cation exchangers have the advantage of increasing tartaric stability, so that other methods can be avoided. Musts were treated in repeated trials. For comparison, the process was also used in wine. In addition, the lactic acid-producing yeast Lachancea thermotolerans was used. The use of a cation exchanger in must or wine always led to a complete removal of potassium and calcium, and at the same time the pH value dropped in some cases to 2.11. Therefore, only part (20%) of a must or wine may be treated to make the final adjustment. The use of the yeast Lachancea thermotolerans could lead to an increase of up to 6 g/L lactic acid, which resulted in an increase of the total acidity.