The effects of several chemico-physical factors (pH, SO 2, and ethanol concentration) on the growth and malolactic activity of Lactobacillus plantarum and Leuconostoc oenos strains, isolated from different Italian red wines, were evaluated. A large individual variability of stress resistance was observed within the two species. The isolates of L. plantarum showed, under the various conditions better growth performances with respect to Leuc. oenos. Ethanol and malic acid concentration, temperature, pH, and inoculum size were modulated according a Central Composite Design (CCD). Two representative strains of each of the two species were individually grown in the various combinations of the CCD, and their activity was evaluated by gas chromatograph on the basis of the CO 2 concentration in the head space of sealed vials. The malolactic activity of the various runs were modelled according to the Gompertz equation. The Gompertz parameters, l~r, ax and length of lag phase, were calculated in order to obtain polynomial equations. The comparison of the models obtained indicated that different factors limit the activities of the two species and that L. plantarum is more resistant to the combined action of various stresses. Having revealed a weaker dependence on the medium modifications as well as higher decarboxylation performances, L. plantarum can be considered as a more efficient alternative to Leuc. oenos for the induction of malolactic fermentation in musts.
Effects of pH, temperature, ethanol, and malate concentration on Lactobacillus plantarum and Leuconostoc oenos: Modelling of the malolactic activity
TORRIANI, Sandra
1995-01-01
Abstract
The effects of several chemico-physical factors (pH, SO 2, and ethanol concentration) on the growth and malolactic activity of Lactobacillus plantarum and Leuconostoc oenos strains, isolated from different Italian red wines, were evaluated. A large individual variability of stress resistance was observed within the two species. The isolates of L. plantarum showed, under the various conditions better growth performances with respect to Leuc. oenos. Ethanol and malic acid concentration, temperature, pH, and inoculum size were modulated according a Central Composite Design (CCD). Two representative strains of each of the two species were individually grown in the various combinations of the CCD, and their activity was evaluated by gas chromatograph on the basis of the CO 2 concentration in the head space of sealed vials. The malolactic activity of the various runs were modelled according to the Gompertz equation. The Gompertz parameters, l~r, ax and length of lag phase, were calculated in order to obtain polynomial equations. The comparison of the models obtained indicated that different factors limit the activities of the two species and that L. plantarum is more resistant to the combined action of various stresses. Having revealed a weaker dependence on the medium modifications as well as higher decarboxylation performances, L. plantarum can be considered as a more efficient alternative to Leuc. oenos for the induction of malolactic fermentation in musts.
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