For 12 Pseudomonas strains, untreated
cellular suspensions showed growth level above
11,000 MPN/ml whereas NEW treated Pseudomonas cell suspensions
(100 mg/L of free chlorine) were sufficient to reduce microbial
viability lower than 30 MPN/ml; to reach the same antimicrobial
activity the free chlorine concentration had to be increased to
200 mg/L for P. fluorescens L1A and I3B strains. P. aeruginosa
DSM939 was sensitive to contact with NEW containing 400, 200
and 100 mg/L of free chlorine. For all Pseudomonas bacteria, no
residual cell viability was recorded after additional 24 h of incubation
at 30 C. Since washing water used in processing plant is
contaminated by organic matter (from soil and vegetable tissues)
and by different microorganisms, based on results related tosimulated washing water, the antibacterial activity of NEW was
further evaluated at 200 mg/L of free chlorine and for a contact time
of 5 min.