Perez, Keila Lizth (2010-05). Efficacy of Consumer-Available Antimicrobials for the Disinfection of Pathogen Contaminated Green Bell Pepper and Efficacy of Consumer Cleaning Methods for the Decontamination of Knives. Master's Thesis. Thesis uri icon

abstract

  • Limited information exists regarding the efficacy of consumer-available antimicrobials for the use on produce surfaces. There is a strong focus on eliminating pathogens from produce at a commercial level, but consumers can achieve pathogen reduction in a domestic setting. The objectives were to determine the ability of consumer-available antimicrobials to disinfect waxed green bell peppers, determine the efficacy of knife cleaning methods, and assess the transfer of contamination. Peppers were inoculated via immersion in a cocktail of rifampicin-resistant Salmonella serovars and Escherichia coli O157:H7 to a final concentration of 5.6 ? 0.5 log CFU/cm2. In study 1, samples of 3 10-cm2 pieces of inoculated pepper were excised from smooth tissue and immersed in 3% (v/v) hydrogen peroxide (H2O2), 2.5% (v/v) acetic acid, 70% (v/v) ethyl alcohol (EtOH), or sterile distilled water (SDW) for various lengths of time. Following treatment, samples were immersed for 30 s in a neutralizer solution. For study 2, inoculated peppers were chopped into 1-cm2 pieces. Knives were treated with one cleaning method: no treatment (control), towel wipe (TW), running hot water for 5 s (5SW), running hot water for 10 s (10SW) or 1% (v/v) detergent solution followed by hot running water for 10 s (ST). After treatments, knives were used to chop cucumbers. Surviving Salmonella and E. coli O157:H7 for both studies were selectively enumerated on lactose-sulfite-phenol red-rifampicin agar following aerobic incubation of plates for 24 h at 35 ?C. Hydrogen peroxide exposure for 5 min resulted in reductions of 1.3 ? 0.3 log CFU/cm2 for both pathogens. Following 1 min exposure to EtOH, pathogens were reduced by 1.3 ? 0.1 3 log CFU/cm2; exposure for >1 min did not result in additional reduction. Acetic acid exposure after 5 min resulted in a Salmonella reduction of 1.0 ? 0.7 log CFU/cm2, but for E. coli O157:H7, exposure resulted in no significant reduction (p<0.05) of pathogens compared to SDW at the various points. For study 2, 5SW, 10SW, and ST were equally effective for knife decontamination. No significant difference (p<0.05) was found between log CFU/cm2 on knife blade and log CFU/cm2 transferred to surface of cucumber; therefore, viable organisms remaining on the knife blade were transferred onto the surface of the cucumber. Findings suggest EtOH and H2O2 may be effective consumer-deployable antimicrobials for surface decontamination of smooth produce, and contaminated produce can contaminate other produce. Further research of antimicrobial exposure on produce sensorial characteristics is also advised in order to determine how various antimicrobial exposure times will affect the quality and sensorial characteristics of the produce commodity.
  • Limited information exists regarding the efficacy of consumer-available antimicrobials for the use on produce surfaces. There is a strong focus on eliminating pathogens from produce at a commercial level, but consumers can achieve pathogen reduction in a domestic setting. The objectives were to determine the ability of consumer-available antimicrobials to disinfect waxed green bell peppers, determine the efficacy of knife cleaning methods, and assess the transfer of contamination.

    Peppers were inoculated via immersion in a cocktail of rifampicin-resistant Salmonella serovars and Escherichia coli O157:H7 to a final concentration of 5.6 ? 0.5 log CFU/cm2. In study 1, samples of 3 10-cm2 pieces of inoculated pepper were excised from smooth tissue and immersed in 3% (v/v) hydrogen peroxide (H2O2), 2.5% (v/v) acetic acid, 70% (v/v) ethyl alcohol (EtOH), or sterile distilled water (SDW) for various lengths of time. Following treatment, samples were immersed for 30 s in a neutralizer solution. For study 2, inoculated peppers were chopped into 1-cm2 pieces. Knives were treated with one cleaning method: no treatment (control), towel wipe (TW), running hot water for 5 s (5SW), running hot water for 10 s (10SW) or 1% (v/v) detergent solution followed by hot running water for 10 s (ST). After treatments, knives were used to chop cucumbers. Surviving Salmonella and E. coli O157:H7 for both studies were selectively enumerated on lactose-sulfite-phenol red-rifampicin agar following aerobic incubation of plates for 24 h at 35 ?C.

    Hydrogen peroxide exposure for 5 min resulted in reductions of 1.3 ? 0.3 log CFU/cm2 for both pathogens. Following 1 min exposure to EtOH, pathogens were reduced by 1.3 ? 0.1 3 log CFU/cm2; exposure for >1 min did not result in additional reduction. Acetic acid exposure after 5 min resulted in a Salmonella reduction of 1.0 ? 0.7 log CFU/cm2, but for E. coli O157:H7, exposure resulted in no significant reduction (p<0.05) of pathogens compared to SDW at the various points. For study 2, 5SW, 10SW, and ST were equally effective for knife decontamination. No significant difference (p<0.05) was found between log CFU/cm2 on knife blade and log CFU/cm2 transferred to surface of cucumber; therefore, viable organisms remaining on the knife blade were transferred onto the surface of the cucumber.

    Findings suggest EtOH and H2O2 may be effective consumer-deployable antimicrobials for surface decontamination of smooth produce, and contaminated produce can contaminate other produce. Further research of antimicrobial exposure on produce sensorial characteristics is also advised in order to determine how various antimicrobial exposure times will affect the quality and sensorial characteristics of the produce commodity.

publication date

  • May 2010