Evaluation of ozone performance as a control agent for foodborne microorganisms

MANZO, RICARDO MARTÍN; ANGHILANTE, MATÍAS; MACHTEY MATÍAS; RUSSEL-WHITE, KAREN; LANCELLE MARIA VERÓNICA; CIBATTARI JAVIER; RISSO, JOSÉ MARÍA; LOVATO MARIA EUGENIA

Congreso; 11th World Congress of Chemical Engineering; 2023

Ozone is a broad-spectrum biocidal agent, which must be generated on site. Since it is not registered as a biocide agent according to the reference lists of the National Administration of Medicines, Food and Medical Technology (ANMAT, Argentina), it was proposed to demonstrate its potential sanitizing and disinfectant effect for general use using target microorganisms.The ozonation tests, both in the gas phase on surfaces and in the liquid phase, were carried out using an ozone generator (OZONA) supplied with industrial O2. Gaseous ozone concentration was determined through UV detector using an on-line O3 monitor. Assays were carried out at different flow rates and current intensities, thus obtaining different ozone transferred doses.For disinfection tests on surfaces, a 40 L ozonation chamber (FDC Advanced) was fed with two different doses of O3. The inactivation of Staphylococcus aureus and Pseudomonas aeruginosa was studied on 30 cm x 30 cm glass plates. Once the plates were sterilized, a known volume of the microbial suspension was placed and dispersed inside each one. After the different treatment times, the microorganisms were recovered and counted, taking as reference the counts of microorganisms recovered from the glass plate without ozonation treatment (control).For the tests in liquid medium, sterile physiological solution was placed in a 250 ml capacity glass reactor, where O3 was bubbled at different doses using a glass diffuser. The dissolved O3 concentration was determined using a colorimetric method. From overnight cultures of Escherichia coli and S. aureus in TSB broth, a working suspension 10 times more concentrated was prepared in sterile physiological solution. For the ozonation experiments, 1.25 ml of the working suspension was added to 48.75 ml of the ozonated physiological solution, immediately homogenized and incubated at different times. At the beginning of the test, the dissolved O3 concentration was also determined. At the end of the incubation, the samples were shaken vigorously and the microbiological count was immediately carried out on TSA agar. The plates were incubated for 16 h at 37°C and the viable CFU/ml were counted.Based on the results obtained for surface disinfection, it was concluded that S. aureus presented greater resistance to ozone as an antimicrobial than P. aeruginosa. However, both microorganisms were completely inactivated after 30 min at a dose of 9 M*s. Regarding the disinfection of liquid media, ozone doses between 15 and 120 μM, and exposure rates between 5 and 70 mM*s were studied, establishing pseudo-first order inactivation kinetics with reductions of up to 7 logarithmic orders.