Malolactic fermentation: acid conversion, not fermentation

The standard

The managed acid conversion decides before the start whether it is allowed, guided or suppressed. That choice follows the acid profile of the fruit, not habit.

Criteria

• The malic acid content is measured, not estimated
• The intended pH is fixed before the start
• Suppression counts as an intervention and is justified
• Completion is confirmed analytically, not assumed

Distinction

Malolactic fermentation ≠ alcoholic fermentation: there yeasts convert sugar, here bacteria convert an acid. The managed acid conversion keeps both processes separate in the cellar. Its suppression requires microbial stability, usually through sulfites.

The oenological importance of this acid conversion in Bordeaux was historically established by Jean Ribéreau-Gayon and Émile Peynaud.