Ensuring the continued efficacy of Brettanomyces control strategies for avoidance of spoilage
- Identify the risk that the spoilage yeast, Brettanomyces, will become sulfite resistant.
- Identify the best way to detect Brettanomyces.
- Develop alternative Brettanomyces control strategies
Brettanomyces can be managed but has not been eliminated from Australian wineries, and loss of value still occurs. A weak point in many Brettanomyces control strategy implementations is a lack of appropriate monitoring tools. Plating methods are laborious and slow, and some rapid methods infer the existence of viable but nonculturable (VBNC) populations that, under certain conditions, may resume growth and spoil the wine. If these VBNC yeast are in fact dead, risk adverse winemakers may be conducting costly and unnecessary processing. If VBNC Brettanomyces do exist, then plating methods will likely underestimate the risk.
Brettanomyces is currently managed with sulfite, but there is increasing pressure to minimise the levels of sulfite in wine. Exposure to sub-lethal dosages creates a situation analogous to that which causes antibiotic resistance in infectious pathogens and may lead to emergence of more sulfite tolerant Brettanomyces strains.
The existence of VBNC populations present in the wine will be determined. The project team has several strategies to improve diagnostic tools and/or interpretation of the results, dependent on whether VBNC status is confirmed or not.
The risk of emergence of sulfite-resistant strain will be evaluated using genomic approaches. After sulfite resistance has been shown to be a real threat, molecular tools will be developed for monitoring in the field, and alternative strategies to control Brett will be developed and evaluated.
This project will generate knowledge that will allow winemakers to better manage and reduce the risk of Brettanomyces spoilage.