Radio-frequency heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice

The efficacy of radio-frequency (RF) heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice was investigated. A 27.12 MHz RF heating system consisted of two parallel-plate electrodes was used, with the sample being placed between them. Black peppers (whole and ground) and red peppers (+16 mesh, -16+25 mesh, and -25 mesh) inoculated with S. Typhimurium and E. coli O157:H7 were treated with RF energy during 50 s for black peppers and 40 s for red peppers, and color change of samples was evaluated after treatment. RF heating for 50 s resulted in 2.80 to 4.29 log CFU/g reductions of S. Typhimurium and E. coli O157:H7 in black peppers and RF heating of red peppers for 40 s reduced pathogens by 3.38 log CFU/g to more than 5 log CFU/g (below the detection limit) without affecting the color quality change. The results suggest that RF heating has the potential for novel thermal process to control foodborne pathogens in spice. (C) 2011 Elsevier B.V. All rights reserved.