The degradation of malic acid by high density cell suspensions of Leuconostoc oenos

Abstract

Washed cell suspensions of Leuconostoc oenos catalysed the degradation of L‐malic acid to L‐lactic acid. Cell suspensions of 1010 cfu ml‐1 degraded 90–95% of the malic acid in a buffer assay system and in wine within 30 min. A reaction time of 6 h was needed to obtain the same extent of degradation with suspensions of 109 cfu ml‐1. With a reaction period of 6 h and an initial malic acid concentration of 3 g 1‐1, reaction variables of pH 2.5‐4.0, temperature 10–30°C, ethanol up to 15%, and L‐lactic acid up to 4 g 1‐1 did not decrease the degradation of malic acid to below 90–95%. Total SO2 at 100 mg 1‐1 decreased the degradation of malic acid to 80%. The degradation (%) of malic acid was decreased when the concentration of malic acid was decreased below 2 g 1‐1. The results indicate the prospect of using high densities of Leuc. oenos cells in membrane bioreactor systems for the rapid, continuous, deacidification of wine.