title: Inactivation of Escherichia coli O157:H7 on radish seeds by sequential treatments with chlorine dioxide, drying, and dry heat without loss of seed viability.
abstract: We developed and validated a treatment to inactivate Escherichia coli O157:H7 on radish seeds without decreasing seed viability. Treatments with aqueous ClO(2) followed by drying and dry-heat treatments were evaluated for efficacy to inactivate the pathogen. Conditions to dry radish seeds after treatment with water (control) or ClO(2) were established. When treated seeds with high water activity (a(w)) (>0.99) were stored at 45°C and 23% relative humidity (RH), the a(w) decreased to <0.30 within 24 h. Drying high-a(w) seeds before exposing them to dry-heat treatment (≥60°C) was essential to preserve seed viability. The germination rate of radish seeds which had been immersed in water for 5 min, dried at 45°C and 23% RH for 24 h, and heated at 70°C for 48 h or at 80°C for 24 h was not significantly decreased (P ≤ 0.05) compared to that of untreated radish seeds. Sequential treatments with ClO(2) (500 μg/ml, 5 min), drying (45°C, 23% RH, 24 h), and dry heating (70°C, 23% RH, 48 h) eliminated E. coli O157:H7 (5.9 log CFU/g) on radish seeds and, consequently, sprouts produced from them without decreasing the germination rate. These sequential treatments are recommended for application to radish seeds intended for sprout production.
authors.affiliation: Graduate School of Life Sciences and Biotechnology, Korea University, Sungbuk-ku, Seoul, Republic of Korea.
authors.forename: Jihyun
authors.initials: J
authors.lastname: Bang
authors.forename: Haeyoung
authors.initials: H
authors.lastname: Kim
authors.forename: Hoikyung
authors.initials: H
authors.lastname: Kim
authors.forename: Larry R
authors.initials: LR
authors.lastname: Beuchat
authors.forename: Jee-Hoon
authors.initials: JH
authors.lastname: Ryu
mesh_terms: D017606:Chlorine Compounds / Q000633:toxicity*; D003890:Desiccation; D004202:Disinfectants / Q000633:toxicity; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D018525:Germination / Q000187:drug effects / Q000528:radiation effects; D006358:Hot Temperature; D050296:Microbial Viability / Q000187:drug effects* / Q000528:radiation effects*; D010087:Oxides / Q000633:toxicity*; D031224:Raphanus / Q000382:microbiology* / Q000502:physiology; D012639:Seeds / Q000382:microbiology / Q000502:physiology
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide