Combined effects of chlorine dioxide, drying, and dry heat treatments in inactivating microorganisms on radish seeds.
We determined the combined effectiveness of ClO(2) (200 and 500 μg/ml, 5 min), air drying [25 °C, 40% relative humidity (RH), 2 h], and mild dry heat (55 °C, 23% RH, up to 48 h) treatments in killing total aerobic bacteria (TAB), Escherichia coli O157:H7, and molds and yeasts (MY) on radish seeds. A 5.1-log reduction in the number of TAB was achieved on radish seeds treated with 200 or 500 μg/ml ClO(2) followed by air drying for 2 h and dry heat treatment for 48 h or 24 h, respectively. When radish seeds were treated with 200 and 500 μg/ml ClO(2), air dried, and heat treated for 12 h and 6 h, respectively, the initial population of E. coli O157:H7 (5.6 log CFU/g) on seeds was reduced to an undetectable level (<0.8 log CFU/g). However, the pathogen was detected in 5-day-old sprouts. The reduction of MY (1.2-1.0 log CFU/g) on radish seeds under similar experimental conditions was not changed significantly during subsequent heat treatment up to 48 h. Results show that treating radish seeds with 500 μg/ml ClO(2), followed by air dried at 25 °C for 2 h and heat treatment at 55 °C for 36 h achieved a >5-log CFU/g reduction of TAB and E. coli O157:H7. These observations will be useful when developing effective strategies and practices to enhance the microbiological safety of radish sprouts.
Graduate School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea.
Jihyun
J
Bang
Haeyoung
H
Kim
Hoikyung
H
Kim
Larry R
LR
Beuchat
Jee-Hoon
JH
Ryu
D017606:Chlorine Compounds / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D003890:Desiccation / Q000379:methods; D004202:Disinfectants / Q000494:pharmacology; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D005516:Food Microbiology; D005519:Food Preservation; D006358:Hot Temperature; D010087:Oxides / Q000494:pharmacology*; D031224:Raphanus / Q000382:microbiology*; D012639:Seeds / Q000382:microbiology*
D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; C025109:chlorine dioxide