Recently, improvement of eggshell hygiene has emerged as an important issue in food industry. Various studies have continued to examine methods for controlling egg-borne pathogen, and among such methods, for table eggs, washing (with UV irradiation) is the most commonly used method. However, this method was not sufficient to control egg microbial contamination. Therefore, the purpose of this study was to verify whether it is appropriate to use ClO2 gas, which has been proven safe in this experiment model, as an alternative to the conventional washing (with UV irradiation) method. As a result, we have identified a range of optimal effectiveness in response to exposure concentrations and time of ClO2 gas. Through experimental models that reflect differences in farm size, a microbial reduction effect of approximately >2 log CFU/eggshell was achieved at 40ppm/8h for small farms, and 160ppm/30min for large farms, indicating greater effectiveness than the conventional method. However, in large-scale experiment, when bulk eggs were stacked and exposed to ClO2 gas, eggs in the depths showed a lower effect by approximately 0.8~1.5 log CFU/eggshell, as compared to the eggs in the upper section. For further study, if technical improvements are achieved in the future studies allowing the gas to better penetrate the depths of stacked eggs, it will be a model that can be more useful to the field.

In recent years, the national surveillance network reported the isolation of Enterobacter sakazakii and coliform from powdered infant formula (PIF). PIF means a breast-milk substitute specially manufactured to satisfy the nutritional requirements of infants during the first month. PIF is not sterile infant food and may be intrinsically contaminated with pathogens, such as E. sakazakii and Salmonella enterica that can cause serious illness in infants. Intrinsic contamination of PIF with E. sakazakii and S. enterica has been a cause of infection and illness in infants. E. sakazakii is an opportunistic pathogens and more commonly found than S. enterica in manufacturing environment. Even low levels of contamination of E. sakazakii and S. enterica in PIF were considered to be a risk factor. Enterobacteriaceae showed the high prevalence and some Enterobacteriaceae causing disease were detected. The infant food industry should be encouraged to reduce the concentration and prevalence of E. sakazakii in both the manufacturing environment and PIF. The presence of these microorganisms in PIF may occur as a results of contamination through ingredients during PIF manufacturing process and from the processing environment during packaging. In order to ensure that ingredients and packaging materials are microbiologically suitable, PIF manufacturer need to be selection of supplier according to stringent criteria (e.g. HACCP, good hygienic practices) and testing of ingredients especially colostrum. In conclusion, it is continually necessary to monitor the potential pathogens and reduce them to improve the microbial quality of non-sterilized PIF.