title: Synergistic effect of chlorine dioxide and drying treatments for inactivating Escherichia coli O157:H7 on radish seeds.
abstract: Studies were done to determine whether calcium hypochlorite (Ca(OCl)(2)) and chlorine dioxide (ClO(2)) treatment followed by drying had a synergistic killing effect on microorganisms on radish seeds intended for sprout production. Uninoculated radish seeds and seeds inoculated with Escherichia coli O157:H7 were treated with water, Ca(OCl)(2) (free chlorine concentrations of 50 or 200 microg/ml), or ClO(2) (50 or 200 microg/ml) for 5 min and subsequently dried at 25 degrees C for up to 24 h. Populations of total aerobic bacteria (TAB), molds and yeasts (MY), and E. coli O157:H7 on the seeds treated with Ca(OCl)(2) were not significantly different (P = 0.05) than populations on seeds treated with ClO(2) at the same concentrations. However, populations of microorganisms on seeds treated with ClO(2) decreased more rapidly during drying. Treatment with ClO(2) (200 microg/ml) followed by drying caused reductions in TAB, MY, and E. coli O157:H7 of 3.1, 2.0, and 3.8 log CFU/g, respectively. When seeds were treated with water, Ca(OCl)(2) (50 or 200 microg/ml), and ClO(2) (50 microg/ml) and subsequently dried, reductions in TAB, MY, and E. coli O157:H7 were 0.2 to 2.0, 0.4 to 2.0, and 1.4 to 2.2 log CFU/g, respectively. Results indicate that inactivation of E. coli O157:H7 on radish seeds is greater after treatment with ClO(2) followed by drying than after treatment with Ca(OCl)(2) followed by drying, thus providing a synergistic treatment combination for reducing the safety risk associated with sprouts produced from these seeds.
authors.affiliation: Division of Human Environmental Sciences, Wonkwang University, Shinyong-dong, Iksan, Jeonbuk, Republic of Korea.
authors.forename: Hoikyung
authors.initials: H
authors.lastname: Kim
authors.forename: Haeyoung
authors.initials: H
authors.lastname: Kim
authors.forename: Jihyun
authors.initials: J
authors.lastname: Bang
authors.forename: Larry R
authors.initials: LR
authors.lastname: Beuchat
authors.forename: Jee-Hoon
authors.initials: JH
authors.lastname: Ryu
mesh_terms: D017610:Calcium Compounds / Q000494:pharmacology*; D017606:Chlorine Compounds / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004202:Disinfectants / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development*; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D006358:Hot Temperature; D010087:Oxides / Q000494:pharmacology*; D031224:Raphanus / Q000382:microbiology*; D012639:Seeds / Q000382:microbiology; D013997:Time Factors
chemical_list: D017610:Calcium Compounds; D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C004488:calcium hypochlorite; C025109:chlorine dioxide