Synergistic Effect of Chlorine Dioxide and Drying Treatments for Inactivating Escherichia coli O157:H7 on Radish Seeds

• Published in: Journal of food protection 2010-07, Vol.73 (7), p.1225-1230
• Main Authors: KIM, Hoikyung, KIM, Haeyoung, BANG, Jihyun, BEUCHAT, Larry R, RYU, Jee-Hoon
• Format: Article
• Language: English
• Subjects: Aerobic bacteria; Bacteria; Biofilms; Biological and medical sciences; Calcium Compounds - pharmacology; Chlorine; Chlorine Compounds - pharmacology; Colony Count, Microbial; Consumer Product Safety; Disinfectants - pharmacology; Dose-Response Relationship, Drug; Drug Synergism; Drying; E coli; Epidemics; Escherichia coli; Escherichia coli O157 - drug effects; Escherichia coli O157 - growth & development; Food contamination & poisoning; Food engineering; Food Handling - methods; Food industries; Food microbiology; Food Preservation - methods; Food safety; Food science; Fundamental and applied biological sciences. Psychology; General aspects; Hot Temperature; Inactivation; Microorganisms; Oxides - pharmacology; Pathogens; Potassium; Radishes; Raphanus - microbiology; Sanitizers; Seeds; Seeds - microbiology; Synergistic effect; Time Factors; Yeasts
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-73.7.1225

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.