Evaluation of plant phenolic extracts as an alternative to sulfur dioxide for the control of Oenococcus oeni and Brettanomyces bruxellensis

Institut für Oenologie, Hochschule Geisenheim University, Von-Lade-Str. 1, 65366 Geisenheim, Germany

Abstract

In the current work, the potential of plant phenolic extracts to replace the ability of SO₂ to inhibit spoilage microorganisms was evaluated. The study included the application of different doses of plant phenolic concentrates to test their antimicrobial activity against O. oeni, and Brettanomyces yeasts. For the evaluation of O. oeni, Chardonnay and Riesling wines were inoculated with the lactic acid bacteria, and antimicrobial agents were added: SO₂ or phenolic concentrates. Then within seven weeks and six months, the levels of malic and lactic acids in the control and treated samples were monitored. In the tests to verify the control of Brettanomyces, oak cubes were contaminated with the spoilage yeasts and later treated with water (control) or two aqueous sanitizing solutions (conventional one: water with citric acid and SO₂; experimental one: containing phenolic concentrates). Later, the corresponding solutions and water were analyzed for the presence of Brettanomyces yeasts by observation and plate numbering. Results confirm the inhibitory capacity of the phenolic concentrates tested regarding these two microorganisms, showing promising results.