Cold Plasma Treatment of Spoilage Microorganisms on Model Food Surface and Real Fruit Tissues

Summary form only given. There has been little attempt to study potential usage of cold atmospheric plasmas to decontaminate the surface of fresh cut fruits. We present results on the inactivation kinetic of various spoilage microorganisms (E. coli, L. monocytogenes, S. cerevisae and G. liquefaciens) deposited on model food surfaces and real fruit tissues. To avoid any adverse thermal damage to the fruit surfaces, we employed a helium-oxygen mixture as the working gas. Using real fruit tissues in the form of cut-surfaces of melon and mango disks, inactivation curves of the spoilage microorganisms were obtained. In order to compare the inactivation rates on fruit surfaces with data obtained on abiotic surfaces, inactivation curves were obtained for cells deposited on membrane disks. S. cerevisae was the hardest of the chosen microorganism to remove, and its cell count on the membrane disks fell below the detection limit after 30 sec of exposure, whilst when deposited on melon and mango the inactivation achieved was about 2 log
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,. G. liquefaciens was always inactivated after 10 sec of treatment. In general, inactivation rates on fruit surfaces were significant lower than the correspondent on membranes; internalization phenomena (the penetration of the microbial cells deep inside the fruit tissues) has been shown happening and can be accounted for the reduced inactivation rates by the cold plasma treatment.