Microbiological study of the effect of a dielectric barrier discharge interaction on processed orange juices exposed to the environment

Abstract

Non-pasteurized juices may contain microorganisms that cause spoilage and public health problems. Owing to their physical properties, dielectric barrier discharge plasmas show high efficiency in the inactivation of microorganisms; in this study, coliforms, Escherichia coli and Salmonella spp. were identified in samples of orange juice collected from street stalls. Microbiological inactivation in orange juice was analyzed using the Weibull model. Using optical emission spectroscopy, the oxidant particles responsible for the inactivation of bacteria are observed. The 200 mL samples were treated for 2.5, 3.5, 5.0, and 6.0 min using a plasma with electrical power of 40 W. It was observed that for aerobic mesophilic, the colony-forming units were reduced from 4.47 to 1.00 Log; for coliforms, from 4.00 to 1.00 Log; and for yeast, from 4.75 to 3.18 Log. The evaluated physicochemical parameters indicate that there are no significant changes in the properties of the juice; therefore, the interaction process with dielectric barrier discharge is a technique that has viability in the inactivation of microorganisms and offers an alternative for the food industry in treating juices.

Keywords:
bacteria; yeast; coliforms; plasma; inactivation