열수(Hot water)를 이용 조제분유 및 선식 준비 시 살균효과를 실험한 결과 60℃ 이상에서 살균 효과를 나타내었으나 조제분유와 선식에 열수를 가하였을 때 발생하는 온도 저하와 조제분유 및 선식 등의 분말 식품에서 biofilm을 생산하여 내열성이 증가되는 E. sakazakii의 특성을 고려하여 70℃ 이상의 열수로 조제분유 및 선식 등을 용해하여야 할 것으로 판단된다. 마이크로웨이브를 이용 E. sakazakii의 살균 효과를 실험한 결과 E. sakazakii를 제어하기 위하여 100 mL의 경우 90초 이상 가열하거나 온도측정이 곤란한 경우에는 최초 끓는 시점까지 가열한 후 냉각하여 섭취하여야할 것으로 조사되었다. 용해된 조제분유 및 선식의 저장 안정성을 평가하기 위해 5~35℃에 48시간 동안 보관하며 E. sakazakii의 성장곡선을 실험한 결과 5℃, 10℃ 냉장온도에서는 48시간까지 증식이 미약하였다. 그러나 냉장 온도에서 사멸하지 않고 미약하게 증식하는 E. sakazakii의 특성을 고려하여 조제분유 및 선식의 냉장 보관은 24시간 이내로 제한하여 섭취하여야 할 것으로 판단된다.

Enterobacter sakazakii was initially referred to as yellow-pigmented Enterobacter cloacae and reclassified in 1980. E. sakazakii infection cause life-threatening meningitis, septicemia, and necrotizing enterocolitis in infants. Powdered infant formula (PIF) and baby foods may be the important vehicle of E. sakazakii infection. It has been reported that E. sakazakii was isolated from PIF and sunsik ingredients produced in Korea. Some infants have been fed sunsik as a weaning diet. Therefore, it is necessary that this organism should be inactivated on preparing PIF and sunsik at homes and in hospitals. The cocktail of three Korean E. sakazakii strains (human, sunsik and soil isolates) were used to investigate the inactivation of this organism with hot water at 50, 60, 65, 70 and 80℃ and microwave heating for 60, 75, 90, 105 and 120 sec. Reconstituted PIF and sunsikwere inoculated with cocktailed vegetative cells of E. sakazakii at 6 log CFU/mL. Thermal inactivation of vegetative cells of E. sakazakii were achieved by reconstituted PIF and sunsik with hot water at 60℃ or greater and with microwave heating at 2,450 MHz for 75 sec or longer. Considering that biofilm formation of E. sakazakii was adapted to survive the dry environment that is PIF and sunsik and thermal resistance increased, it is suggested that inactivation of E. sakazakii was used by hot water at 70℃ or greater and microwave heating for 90 sec or longer. Reconstituted PIF and sunsik were inoculated with cocktailed vegetative cells of E. sakazakii at 2 to 3 log CFU/mL to investigate the growth curve of this organism and stored at 5, 10, 15, 20, 25, 30 and 35℃. Viable counts slightly changed at 5, 10℃ during 48 h but grew at 15℃ or greater. Considering that E. sakazakii is able to grow in infant formula milk at refrigerator temperature, reconstituted PIF and sunsik that are not immediately consumed should be discarded or stored at refrigeration temperatures within 24 h.

• 김중범
• 박용배
• 이명진
• 김기철
• 허정원
• 김대환
• 이정복
• 김종찬
• 최재호
• 오덕환