Ultraviolet Light Emitting Diodes Technology for the Reduction of Micro-Organisms in Apple Juice
The aims of these investigations were to study the efficacy of UV-C light emitting diode systems (LED) operating at 263 nm and 279 nm for the inactivation of Listeria monocytogenes ATCC 19115, Salmonella enterica serovar Muenchen ATCC BAA 1764 and Escherichia coli ATCC 35150 in apple juice. Specific bacteria concentrations were inoculated in apple juice and irradiated at the specified UV doses ranging between 0 to 12 mJ·cm–2. Additionally, higher UV irradiation doses that ranged between 0 to 160 mJ·cm–2 were delivered to the apple juice; and both polyphenols and vitamins were profiled via LC-MS/MS analysis. The polyphenol and vitamin results demonstrated that UV-C irradiation in apple juices at relevant commercial UV doses induced significant reductions in the concentrations of selected polyphenols and vitamins, p < 0.05. The log reduction kinetics of microorganisms followed log-linear and with higher R2 (> 0.95). The D10 values of 4.16 and 3.84 mJ·cm–2 were obtained from the inactivation of Escherichia coli, and Listeria monocytogenes, at 263nm; and 3.56 and 3.50 mJ·cm–2 for Salmonella Muenchen and Listeria monocytogenes, respectively at 279nm. Current results also indicate that high temperature and longer exposure times can affected levels of bioactive compounds in apple juice. Ultrasound exposures retained the bioactive content of apple juice. In contrast, ozone degraded the polyphenols. The degradation was a function of ozone concentration and exposure time. The need to optimize processes in terms of bioactive retention in beverages, demands more bench research to streamline processes and requires further optimization.
"Ultraviolet Light Emitting Diodes Technology for the Reduction of Micro-Organisms in Apple Juice"
ETD Collection for Tennessee State University.