Combined use of thermo-ultrasound and cinnamon leaf essential oil to inactivate Saccharomyces cerevisiae in natural orange and pomegranate juices

• Acceptable concentrations of cinnamon leaf essential oil in natural juices was determined.
• The highest concentrations of CLEO improved the color of pomegranate juice.
• Combination of ultrasound, mild temperature and essential oil enhance the inactivation of Saccharomyces cerevisiae in juices.
• Bioactive compounds of juices could affect inactivation and survival of S. cerevisiae.

The inactivation of Saccharomyces cerevisiae in natural orange and pomegranate juices untreated (control) and treated with mild temperature (50 °C), cinnamon leaf essential oil, thermo-ultrasound (24 KHz; 33.31 W mL−1; 30 min; 50 °C), alone or in combination, and its survival under refrigerated conditions (5 °C, 28 days) were studied. Additionally, the maximum concentration of cinnamon leaf essential oil accepted by consumers in both juices was determined by sensory analysis. A significant reduction in the yeast population was obtained compared to controls. The most effective treatment to inactive yeast cells was the combination of ultrasound and cinnamon leaf essential oil during 30 min at 50 °C, which, from an initial population of 5.13 log cfu ml−1, achieved significant 2.81 ± 0.19 and 2.52 ± 0.26 log-reductions in natural pomegranate and orange juices respectively. During refrigerated storage (5 °C, 28 days), the S. cerevisiae population in orange and pomegranate juices, treated with ultrasound and cinnamon leaf essential oil at 50 °C for 30 min, decreased by 1.55 ± 0.19 and 0.68 ± 0.16 log respectively, while the controls kept the yeast population without significant changes.