OxyFile #422

Efficacy of ozonated water against various food-related 
microorganisms.

Restaino L; Frampton EW; Hemphill JB; Palnikar P

R & F Laboratories, Inc., Bridgeview, Illinois 60455, USA.

Appl Environ Microbiol, 61: 9, 1995 Sep, 3471-5

Abstract

The antimicrobial effects of ozonated water in a recirculating 
concurrent reactor were evaluated against four gram-positive and 
four gram-negative bacteria, two yeasts, and spores of Aspergillus 
niger. More than 5 log units each of Salmonella typhimurium and 
Escherichia coli cells were killed instantaneously in ozonated 
water with or without addition of 20 ppm of soluble starch (SS). 
In ozonated water, death rates among the gram-negative bacteria--
S. typhimurium, E. coli, Pseudomonas aeruginosa, and Yersinia 
enterocolitica--were not significantly different (P > 0.05). Among 
gram-positive bacteria, Listeria monocytogenes was significantly P 
< 0.05) more sensitive than either Staphylococcus aureus or 
Enterococcus faecalis. In the presence of organic material, death 
rates of S. aureus compared with L. monocytogenes and E. coli 
compared with S. typhimurium in ozonated water were not 
significantly (P > 0.05) affected by SS addition but were 
significantly reduced (P < 0.05) by addition of 20 ppm of bovine 
serum albumin (BSA). More than 4.5 log units each of Candida 
albicans and Zygosaccharomyces bailii cells were killed 
instantaneously in ozonated water, whereas less than 1 log unit of 
Aspergillus niger spores was killed after a 5-min exposure. The 
average ozone output levels in the deionized water (0.188 mg/ml) 
or water with SS (0.198 mg/ml) did not differ significantly (P < 
0.05) but were significantly lower in water containing BSA (0.149 
mg/ml).