Effectiveness of chitosan preparations against Brettanomyces bruxellensis grown in culture media and red wines

Abstract

Aim: The antimicrobial properties of chitosan from different sources (fungal, crab shell, and lactate-forms) against Brettanomyces bruxellensis in culture media and red wines were investigated. Methods and results: While concentrations of 4 to 8 g/hL were needed for crab shell or lactate-forms of chitosan to reduce yeast viability in liquid media, fungal chitosan did not exhibit antimicrobial activities no matter the concentration. B. bruxellensis E1 and I1a were inoculated into Cabernet-Sauvignon wine at 106 cfu/mL and treated with 0, 4, 8 and 12 g/hL fungal chitosan. In contrast to previous results with media, addition of fungal chitosan to a red wine resulted in a three-log reduction of culturability. Addition of fungal chitosan also reduced the viability of B. bruxellensis growing in oak barrels containing Merlot wine from 105 cfu/mL down to ≈102 cfu/mL. Conclusion: Depending on concentration, all preparations of chitosan added to red wines greatly reduced populations of B. bruxellensis. However, wines were not completely stable after treatment as populations eventually increased. Significance and impact of the study: As B. bruxellensis is considered to be a worldwide threat to wine quality, it is crucial to improve knowledge of alternative control methods and strategies such as chitosan that winemakers can apply.