Development of a Screening Method and Device for the Detection of Escherichia coli from Agri-Food Production Environments and Fresh Produce

Abstract

This study was conducted to develop a screening method using Colilert-18 and a device for the detection of from agri-food production environments and fresh vegetables. The specificity and sensitivity of Colilert-18 by temperature (37°C and 44°C) were evaluated with 38 and 78 non- strains. The false-positive rate was 3.8% (3/78) and 0% (0/78) at 37°C and 44°C, respectively. The detection limit of at 37°C at<1.0 log CFU/250 ml was lower than that at 44°C. The efficiency of the developed device, which comprised an incubator equipped with a UV lamp to detect in the field, was evaluated by measuring the temperature and UV lamp brightness. The difference between the set temperature and actual temperature of the developed device was about 1.0°C. When applying the developed method and device to various samples, including utensils, gloves, irrigation water, seeds, and vegetables, there were no differences in detection rates of compared with the Korean Food Code method. For sanitary disposal of culture samples after experiments, the sterilization effect of sodium dichloroisocyanurate (NaDCC) tablets was assessed for use as a substitute for an autoclave. The addition of one tablet of NaDCC per 50 ml was sufficient to kill cultured in Colilert-18. These results show that the developed protocol and device can efficiently detect from agri-food production environments and vegetables.