Acetaldehyde metabolism by wine lactic acid bacteria

Area of Science:

• Enology
• Food Microbiology
• Biochemistry

Background:

• Acetaldehyde is a volatile compound crucial for the flavor profile of fermented foods, particularly wines.
• Understanding acetaldehyde metabolism is vital for controlling wine's sensory and color qualities.
• Sulfur dioxide (SO(2)) is commonly used in winemaking, and its interaction with acetaldehyde is significant.

Purpose of the Study:

• To investigate the capacity of malolactic bacteria, specifically Lactobacillus and Oenococcus strains, to metabolize acetaldehyde.
• To determine if these bacteria can degrade both free and SO(2)-bound acetaldehyde.
• To assess the impact of acetaldehyde degradation by malolactic bacteria on winemaking.

Main Methods:

• Utilized a resting cell system to test the metabolic activity of nine Lactobacillus and Oenococcus strains on acetaldehyde.
• Assessed the degradation of SO(2)-bound acetaldehyde by specific bacterial strains.
• Conducted coincubation experiments with Saccharomyces bayanus and Oenococcus oeni to observe yeast-derived acetaldehyde metabolism.

Main Results:

• Nine out of eleven tested strains, belonging to Lactobacillus and Oenococcus genera, successfully metabolized acetaldehyde, producing acetic acid and ethanol.
• Two Pediococcus strains did not metabolize acetaldehyde.
• Both Lactobacillus and Oenococcus strains demonstrated the ability to degrade SO(2)-bound acetaldehyde.
• Oenococcus oeni Lo111 effectively metabolized acetaldehyde produced by Saccharomyces bayanus.

Conclusions:

• Malolactic bacteria, particularly Lactobacillus and Oenococcus, play a role in acetaldehyde degradation during winemaking.
• The ability to metabolize both free and SO(2)-bound acetaldehyde by these bacteria has significant implications for wine's sensory attributes and color.
• This microbial activity influences the effectiveness and necessity of SO(2) additions in wine production.