Corona discharge plasma jet for inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on inoculated pork and its impact on meat quality attributes

Abstract

Corona discharge plasma jet (CDPJ) was used for inactivation of Escherichia coli O157:H7 and Listeria monocytogenes inoculated experimentally onto the surfaces of fresh and frozen pork. CDPJ was generated with an output voltage of 20 kV direct current and a frequency of 58 kHz. Optimal inactivation was found with plasma created at a current of 1.5 A, and at a span length of 25 mm between the plasma electrode tip and the sample. Following CDPJ treatment (0–120 s) of pork samples, reductions in E. coli O157:H7 and L. monocytogenes were 1.5 log and >1.0 log units, respectively. The inactivation pattern fitted well to the Singh-Heldman model or pseudo-first-order kinetics. Compared to untreated pork, with the exception of color and appearance, no statistically significant (P > 0.05) changes were observed in volatile basic nitrogen, peroxide value, or 2-thiobarbituric acid reactive substances of CDPJ-treated pork. Furthermore, CDPJ treatment had no significant impact on the sensory characteristics of frozen pork although there was some effect on unfrozen pork.