Tyramine Formation by Pediococcus spp. during Beer Fermentation

Area of Science:

• Microbiology
• Food Science
• Fermentation Technology

Background:

• Tyramine is a biogenic amine found in fermented foods.
• Pediococcus species are known contaminants in industrial beer fermentations.
• High tyramine levels in beer can be a concern for quality and safety.

Purpose of the Study:

• To investigate the role of Pediococcus species in tyramine production during beer fermentation.
• To establish a correlation between Pediococcus contamination levels and tyramine formation.
• To assess the stability of tyramine production by Pediococcus strains.

Main Methods:

• Isolation of Pediococcus species from industrial beer fermentations with high tyramine.
• Quantification of Pediococcus colony-forming units (CFU) per milliliter.
• Measurement of tyramine levels in mg/liter.
• Evaluation of tyramine production after prolonged storage or transfer to new media.

Main Results:

• Pediococcus species were confirmed to produce tyramine during beer fermentation.
• Tyramine levels correlated directly with Pediococcus contamination: <5 mg/liter (4x10³-1x10⁴ CFU/ml), 5-15 mg/liter (1x10⁴-5x10⁴ CFU/ml), and 15-20 mg/liter (>5x10⁴ CFU/ml).
• Isolated Pediococcus strains lost tyramine-producing ability after prolonged storage or transfer.

Conclusions:

• Pediococcus species are significant contributors to tyramine formation in beer.
• Tyramine concentration in beer serves as a reliable indicator of Pediococcus contamination.
• Factors such as storage and subculturing can affect the tyramine-producing capacity of Pediococcus strains.