Alfalfa sprouts have been implicated in several salmonellosis outbreaks in recent
years. Electrolysis of a NaCl solution generates, in the anode side of a two-chamber
electrolyzer, acidic electrolyzed oxidizing (EO) water which contains Cl₂, HOC1,
dissolved oxygen, and it is characterized by a low pH and a high oxidation reduction
potential (ORP). The disinfectant effects of EO water against Salmonella enterica both
in an aqueous system and on artificially contaminated alfalfa seeds were determined.
EO water (pH 2.54 to 2.38, and ORP +1083 to +1092 mV) exhibited strong potential
for the inactivation of S. enterica in an aqueous system (producing a reduction of at
least 6.6 log CFU/ml). Treatment of artificially contaminated alfalfa seeds with EO
water at a seed-to-EO water ratio of 1:100 for 15 and 60 min significantly reduced
Salmonella populations by 2.04 and 1.96 log CFU/g, respectively (P < 0.05), while a
Butterfield's buffer wash decreased Salmonella populations by 0.18 and 0.23 log
CFU/g, respectively. Germination of seeds was not significantly affected (P > 0.05) by
a treatment for up to 60 min in electrolyzed water. Further studies were undertaken to
investigate whether •OH radical species are present in EO water or are formed when
EO water reacts with iron ions. Electron spin resonance spectroscopy (ESR) coupled with the spin trapping technique was used for the detection of free radicals. The
DMPO-OH spin adduct, characteristic to •OH radicals, was not observed. In the
presence of DMPO (5,5-dimethyl-l-pyrroline-N-oxide), the reactions of EO water
with Fe³⁺ and Fe²⁺ yielded the spin adduct DMPO-OH. However, the addition of •OH
radical scavengers (ethanol, methanol, and mannitol) to the reaction mixture, did not
reduce the DMPO-OH signal nor generated the characteristic DMPO-alkyl spin
adducts. This indicated that the DMPO-OH signal was due to a nucleophilic addition
of water to DMPO and not to trapping of OH radicals. Addition of DMPO to EO
water, generated an ESR spectrum identical with that of 5,5-dimethyl-2-pyrrolidone-
N-oxyl (DMPOX). Hypochlorous acid, generated in the anode chamber, is proposed to
oxidize the spin trap DMPO with the formation of DMPOX. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27048 |
| Date | 11 December 2003 |
| Creators | Stan, Silvia D. |
| Contributors | Daeschel, Mark A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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