Decontamination of Raw Produce by Surface Microdischarge and the Evaluation of Its Damage to Cellular Components

The use of surface microdischarge (SMD) for the bacterial decontamination of raw produce was evaluated. With 1 min of SMD treatment, >2 logarithmic reduction in Escherichia coli O157:H7 was consistently observed. The scanning electron microscopy of E. coli O157:H7 show that SMD damages the cell membrane, leads to cell expansion, and eventually lysis. The attenuated total reflectance-Fourier-transform infrared spectroscopy characterization of E. coli O157:H7 and lipopolysaccharides (LPS) shows that SMD causes (a) the oxidation of cellular components by forming COOH and COO ⁻ groups inside and on the cell wall, and (b) the modification of polysaccharides and phosphorus-containing groups found in phospholipids and DNA. Further characterization with X-ray photoelectron spectroscopy suggests SMD mainly modifies the O-chain and core-polysaccharide part of LPS.