Anti-yeast activity of natural compounds: In vitro and in vivo tests

• The anti-yeast activity of trans-2-hexanal, cinnamon, eugenol and thymol was addressed by in vitro and in vivo tests.
• A Central Composite Design (CCD) was also carried out to highlight possible synergistic effects between trans-2-hexanal, cinnamon and eugenol.
• Compounds were all effective against yeasts.
• Their combination further reduced the active agent concentration.

The anti-yeast activity of some natural compounds (trans-2-hexanal, cinnamon oil, eugenol and thymol) was addressed by in vitro and in vivo tests. First, their efficacy was tested against some yeasts. By a sensory evaluation the thymol was discarded and the other three natural preservatives were tested in grape juice inoculated with a cocktail of selected yeasts. The most effective compound was trans-2-hexanal. A Central Composite Design (CCD) was also carried out to highlight possible synergistic effects between trans-2-hexanal, cinnamon oil and eugenol. Results showed that compounds were all effective against yeasts and their combination further reduced the active agent concentration. To finally assess the activity of the six most effective combinations of the CCD, a fresh grape juice added with compounds and stored at two storage temperatures, was monitored during time. Results confirmed the effectiveness of the three natural compounds in providing an immediate and significant protection of juice to yeast proliferation.