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

The inactivation of Saccharomyces cerevisiae in natural orange and pomegranate juices untreated (control) and treated with mild temperature (50 degrees C), cinnamon leaf essential oil, thermo-ultrasound (24 KHz; 33.31 W mL(-1); 30 min; 50 degrees C), alone or in combination, and its survival under refrigerated conditions (5 degrees 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 degrees 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 degrees C, 28 days), the S. cerevisiae population in orange and pomegranate juices, treated with ultrasound and cinnamon leaf essential oil at 50 degrees 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. (C) 2016 Elsevier Ltd. All rights reserved.