Studies were done to determine whether calcium hypochlorite (Ca(OCl) 2) and chlorine dioxide (C1O2) 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 μg/ml), or C1O2 (50 or 200 μg/ml) for 5 min and subsequently dried at 25°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 C1O2 at the same concentrations. However, populations of microorganisms on seeds treated with C1O2 decreased more rapidly during drying. Treatment with C1O2 (200 μg/ml) followed by drying caused reductions in TAB, MY, and E. coli 0157: 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 μg/ml), and C1O 2 (50 μg/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 OL57: H7 on radish seeds is greater after treatment with C1O2 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.
ASJC Scopus subject areas
- Food Science