3. Results and discussion
3.1. Comparison of seed viability as affected by aqueous chlorine
dioxide or dry-heat treatment
Table 1 shows the changes in the germination rates of sprout
seeds after treatment with aqueous ClO2 (200 mg/ml, 5 min) or dryheat
(80 C/23% RH, 24 h). Before treatment with aqueous ClO2 or
dry heat (controls), seeds had germination rates of 82.0e99.3%.
Germination rates of alfalfa, kohlrabi, kyona, mustard, pak choi, red
radish, and tatsoi seeds did not decrease significantly (P > 0.05)
after treatment with aqueous ClO2. Although the germination rate
of red radish seeds was not significantly (P > 0.05) changed after
ClO2 treatment, its standard deviations were markedly increased.
When sprout seeds were treated with dry heat, the germination
rates of pak choi, red kohlrabi, red radish, red young radish, tatsoi,
and violet radish seeds did not decrease significantly (P > 0.05). Of
the 11 sprout seed types tested, the viability of three seed types
(pak choi, red radish, and tatsoi) was not significantly reduced by
treatment with aqueous ClO2 or dry heat. Because pak choi seeds
showed the highest germination rate on average after aqueous ClO2
or dry heat treatments, they were used to investigate the lethality
of sequential treatments of ClO2, drying, and dry heat against E. coli
O157:H7 or S. enterica.