Acetaldehyde utilization by Leuconostoc species.

Area of Science:

• Dairy Microbiology
• Food Chemistry

Background:

• Acetaldehyde is a key flavor compound in fermented dairy products.
• Understanding its metabolism by lactic acid bacteria (LAB) is crucial for controlling flavor profiles.

Purpose of the Study:

• To investigate the acetaldehyde utilization capabilities of specific Leuconostoc strains.
• To examine the impact of environmental factors (pH, temperature) on acetaldehyde metabolism.
• To assess the effect of mixed cultures and specific bacterial additions on acetaldehyde concentration.

Main Methods:

• Culturing single strains of Leuconostoc dextranicum and L. mesenteroides in milk at varying pH and temperatures (21°C, 30°C).
• Analyzing acetaldehyde production and consumption in different two-strain combinations of lactic streptococci and leuconostocs.
• Monitoring acetaldehyde concentration changes in lactic streptococcal cultures after inoculation with L. citrovorum and incubation at low temperatures (21°C, 5°C).

Main Results:

• Both Leuconostoc dextranicum and L. mesenteroides demonstrated acetaldehyde utilization in acidified and non-acidified milk.
• L. dextranicum showed faster acetaldehyde utilization than L. mesenteroides under conditions mimicking ripened dairy cultures.
• Significant variability in acetaldehyde production and utilization was observed across different mixed bacterial cultures.
• Adding a large inoculum of L. citrovorum effectively reduced acetaldehyde concentration in lactic streptococcal cultures.

Conclusions:

• Leuconostoc species play a role in acetaldehyde metabolism during dairy fermentation.
• Strain-specific and culture-specific interactions significantly influence acetaldehyde dynamics.
• L. citrovorum can be employed to manage acetaldehyde levels in fermented dairy products.