Inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium in black and red pepper by vacuumed hydrogen peroxide vapour

Aims: In this study, the efficacy of using vacuumed hydrogen peroxide vapour (VHPV) to inactivate foodborne pathogens in whole dried black pepper (Piper nigrum) and powdered dried red pepper (Capsicum annuum) was evaluated.

Methods and results: Black and red pepper inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium were subjected to 3.81, 7.93, 12.33, 17.04 and 21.67 mg l^-1 VHPV for 1 min, and the change in pepper colour was evaluated after treatment. Pathogen quantities decreased with increasing hydrogen peroxide concentration. For black pepper, the 21.67 mg l^-1 VHPV treatment decreased E. coli O157:H7 and S. Typhimurium quantities by >6.12 and 4.52 log CFU per gram, respectively, without causing colour change. In addition, the 21.67 mg l^-1 VHPV treatment caused 4.35 and 2.36 log CFU per gram reductions in these two pathogen quantities in red pepper, respectively. During the VHPV treatment, colour values of peppers did not significantly change.

Conclusions: VHPV effectively reduced the levels of foodborne pathogens in black and red pepper while inducing minimal colour changes.

Significance and impact of the study: Hydrogen peroxide vapour (HPV) is typically used as a sterilization method for medical devices, and many studies have confirmed the effectiveness of HPV or the gaseous phase of hydrogen peroxide on the inactivation of micro-organisms. However, using HPV for food pasteurization has rarely been studied. In the present study, we confirmed that VHPV effectively reduced the levels of pathogens in black and red pepper without colour changes.