Ultrasound pretreatment and ozonation as a strategy to reduce sulphites in winemaking: effects on grape microbiota and Lachancea thermotolerans establishment

Abstract

Ozone is a promising grape disinfectant for reducing sulphur dioxide use, although its efficacy may be limited by the waxy bloom covering the berry surface. This study assessed a sequential ultrasound (US) pretreatment followed by ozonation (O₃), with particular attention to grape sanitation and the establishment of Lachancea thermotolerans. Grapes received direct ozonation for 30 min, 10 min of ultrasound followed by 30 min of ozonation, or 40 mg/L sulphites. L. thermotolerans active dry yeast was then inoculated at 5 g/hL. Antimicrobial effects were assessed by plate counts before inoculation, while fermentation performance was evaluated through parameters including lactic-acid production. Both ozone-based treatments achieved microbial reductions comparable to sulphites. The US+O₃ treatment was slightly more effective, reducing the initial yeast population by 2 log CFU/mL. Lactic-acid production, an indicator of L. thermotoleransestablishment and activity, tended to be highest in must from US+O₃-treated grapes, intermediate after O₃ alone and lowest after sulphite treatment. Ozonation can therefore provide sanitation equivalent to conventional sulphiting, while ultrasound pretreatment may enhance its effectiveness and create more favourable conditions for selected non-Saccharomyces yeasts.

References

1. Rodríguez, Y. Ultrasound Pretreatment and Ozonation as a Strategy to Reduce Sulphites in Winemaking: Effects on Grape Microbiota and Lachancea thermotolerans Establishment. Recording of the presentation delivered at Enoforum Spain 2026, Zaragoza, 20–21 May 2026. Available soon on Infowine Premium: https://vinidea.it/es/brand/infowine/