Cronobacter Support
06-03-2009, 05:21 PM
1st International Conference on Cronobacter Poster Abstract 54
Thermal resistance, growth and inactivation of Enterobacter sakazakii in powdered and reconstituted infant formula
Enterobacter sakazakii has recently been recognized as an opportunistic foodborne pathogen. Dry infant formula has been implicated as the mode of transmission for this microorganism, which may cause a severe form of neonatal meningitis and high fatality rate among infants. The objectives of this study were to investigate the heat resistance, growth pattern and inactivation under room and refrigeration temperatures storage of dry and reconstituted infant formula milk (IFM). E. sakazakii strains (8 strains) showed a wide variability in heat resistance at different temperatures (55, 60, and 63 oC). The D-values at 55 oC ranged from 1.51-14.83 min, at 60 oC from 0.17 to 2.71 min and at 63 oC from 0.05 min to 0.88 min. The calculated z-values for the studied E. sakazakii strains ranged from 3.76-10.11 oC. A household microwave was used to heat 60 ml portions of reconstituted IFM. The reconstituted IFM was inoculated with 1 × 10 5 CFU/ml of a cocktail of four heat-resistant strains of E. sakazakii. Heating reconstituted IFM from 20-30 s was not effective in reducing E. sakazakii. However, heating for 40-50 s was effective in eradicating all inoculated E. sakazakii. Additionally, storing powdered IFM for 15 days at refrigeration resulted in at least a 1 log unit reduction in inoculated E. sakazakii strains. Whereas storing reconstituted IFM at refrigeration for two weeks resulted in more than 2 log units reduction in E. sakazakii. However, keeping reconstituted IFM at room temperature resulted in a very sharp increase in E. sakazakii count. Lactobacillus acidophilus was examined for its antimicrobial activity against E. sakazakii. However, no antimicrobial effect for Lactobacillus acidophilus was observed.
Murad A. Al-Holy1, Hamzah A. Al-Qadiri2, Mahmoud, M. Abu-Ghoush1, Barbara A. Rasco3
1 Department of Clinical Nutrition and Dietetics, Faculty of Allied Health Sciences, Hashemite University, P.O Box: 150459, Zarqa-Jordan. 2 Department of Nutrition and Food Technology, Faculty of Agriculture, University of Jordan, Amman-Jordan. 3 Department of Food Science and Human Nutrition, Box 646376, Washington State University, Pullman, WA 99164-6373
Thermal resistance, growth and inactivation of Enterobacter sakazakii in powdered and reconstituted infant formula
Enterobacter sakazakii has recently been recognized as an opportunistic foodborne pathogen. Dry infant formula has been implicated as the mode of transmission for this microorganism, which may cause a severe form of neonatal meningitis and high fatality rate among infants. The objectives of this study were to investigate the heat resistance, growth pattern and inactivation under room and refrigeration temperatures storage of dry and reconstituted infant formula milk (IFM). E. sakazakii strains (8 strains) showed a wide variability in heat resistance at different temperatures (55, 60, and 63 oC). The D-values at 55 oC ranged from 1.51-14.83 min, at 60 oC from 0.17 to 2.71 min and at 63 oC from 0.05 min to 0.88 min. The calculated z-values for the studied E. sakazakii strains ranged from 3.76-10.11 oC. A household microwave was used to heat 60 ml portions of reconstituted IFM. The reconstituted IFM was inoculated with 1 × 10 5 CFU/ml of a cocktail of four heat-resistant strains of E. sakazakii. Heating reconstituted IFM from 20-30 s was not effective in reducing E. sakazakii. However, heating for 40-50 s was effective in eradicating all inoculated E. sakazakii. Additionally, storing powdered IFM for 15 days at refrigeration resulted in at least a 1 log unit reduction in inoculated E. sakazakii strains. Whereas storing reconstituted IFM at refrigeration for two weeks resulted in more than 2 log units reduction in E. sakazakii. However, keeping reconstituted IFM at room temperature resulted in a very sharp increase in E. sakazakii count. Lactobacillus acidophilus was examined for its antimicrobial activity against E. sakazakii. However, no antimicrobial effect for Lactobacillus acidophilus was observed.
Murad A. Al-Holy1, Hamzah A. Al-Qadiri2, Mahmoud, M. Abu-Ghoush1, Barbara A. Rasco3
1 Department of Clinical Nutrition and Dietetics, Faculty of Allied Health Sciences, Hashemite University, P.O Box: 150459, Zarqa-Jordan. 2 Department of Nutrition and Food Technology, Faculty of Agriculture, University of Jordan, Amman-Jordan. 3 Department of Food Science and Human Nutrition, Box 646376, Washington State University, Pullman, WA 99164-6373