Purpose: Tests were conducted to assess the antimicrobial efficacy of PAA between 2000 and 4000 ppm with and without Peradigm® to reduce Chaetomium globosum ATCC 6205 inoculated onto carriers.
Methods: PAA concentration, addition of booster, contact time, and temperature, were evaluated in tests performed using carriers. Stainless steel strips inoculated with spores of C. globosum were dried overnight and tested against 2000 to 4000 ppm PAA with and without Peradigm®, with 10 and 30 s contact times at 55 and 60 °C. The strips were neutralized in Letheen broth with sodium thiosulfate, were sonicated and vortexed. The resulting solutions were diluted and plated on Petrifilm™ YM plates, incubated 5 days at 30 °C and then counted.
Results: Greater reduction was achieved using Peradigm®, with complete kill (5.71 log reduction) achieved using a 1:50 ratio of Peradigm® with 4000 ppm PAA at a contact time of 30 seconds at 55ºC, compared with a 1.57 log reduction without using Peradigm®. At 60 °C, all samples tested at 2000, 3000, and 4000 ppm PAA with 1:50 Peradigm® resulted in complete kill at 30 seconds.
Significance: C. globosum (ATCC 6205) demonstrated persistence despite the presence of heat and biocide, comparable to or greater than some bacterial endospores previously tested. Clarity® at concentrations between 2000 and 4000 ppm PAA was able to achieve complete reduction of this organism using the booster product Peradigm®. Use of Peradigm® was critical in achieving complete reduction of the organism at a lower test temperature of 55 °C, preferable when using PET bottles, to avoid softening or deformation.