The study was conducted to evaluate data on washing methods of fresh produce using chlorinated water to establish a standard method for the small or medium sized food industry for ensuring microbiological safety of fresh produce.
To evaluate the appropriate concentration of chlorine water and treatment time, cut produce of lettuce, cabbage and cucumber was inoculated with
Escherichia coli O157: H7 and submerged in chlorine water (100, 200 and 400 ppm of free available chlorine) for 1, 3, 5 and 10 min with gentle agitation at room temperature. Population of
E. coli O157: H7 on lettuce, cabbage and cucumber decreased significantly (1-1.5 log
10 cfu/g) within 1 min, regardless of available chlorine concentration. However, the population of
E. coli O157: H7 did not decrease much (<0.5 log
10 cfu/g) when the treatment time was extended to 10 min. Normal microflora also decreased significantly (0.5-1.9 log
10 cfu/g) within 1 min, regardless of available chlorine concentration and fresh produce used. Extended treatment time was not found to be effective.
Reduction of
E. coli O157: H7 on the surface and the cut edge of lettuce, cabbage and cucumber was also evaluated. It was found that the number of
E. coli O157: H7 attached at the cut edge was consistently higher than at the surface, regardless of vegetable used. Therefore, cutting process of fresh produce should be taken into account and a standard process must be developed to ensure microbiological safety of fresh cut vegetables and fruits.
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