Production of SO₂ binding compounds and SO₂ by Saccharomyces during alcoholic fermentation and the impact on malolactic fermentation.

摘要

The objective of this study was to investigate the production of SO₂ and SO₂ binding compounds by wine yeast and the impact of the production of these compounds on the MLF at various time points during alcoholic fermentation. Fermentations were observed for a number of commercial wine yeasts in a synthetic grape juice and Pinot gris juice and SO₂, acetaldehyde, pyruvic acid and alpha -ketoglutarate. Measurements were taken at multiple time points during the fermentation. Samples were taken from the fermentations at weekly intervals, sterile filtered, and inoculated with O. oeni strain VFO to induce MLF. Significant differences between the amount of SO₂, acetaldehyde and pyruvic acid produced by the various yeast strains were noted. Some yeast strains such as FX10, CK S102, F15 and M69, produced significantly higher SO₂ concentrations than other yeast strains and MLF was inhibited in these wines. Insignificant free SO₂ was measured, indicating that bound SO₂ rather than free SO₂ was responsible for inhibition. At almost all time points of the alcoholic fermentation, acetaldehyde bound SO₂ was determined to be the dominant species of bound SO₂ present, suggesting that MLF inhibition by bound SO₂ was due to acetaldehyde bound SO₂.