Heat resistance of Cronobacter species (Enterobacter sakazakii) in milk and special feeding formula.
OBJECTIVE
To determine D- and z-values of Cronobacter species (Enterobacter sakazakii) in different reconstituted milk and special feeding formula and the effect of reconstitution of powdered milk and special feeding formula with hot water on the survival of the micro-organism.


RESULTS
Five Cronobacter species (four C. sakazakii isolates and C. muytjensii) were heated in reconstituted milk or feeding formula pre-equilibrated at 52-58 degrees C for various times or mixed with powdered milk or feeding formula prior to reconstitution with water at 60-100 degrees C. The D-values of Cronobacter at 52-58 degrees C were significantly higher in whole milk (22.10-0.68 min) than in low fat (15.87-0.62 min) or skim milk (15.30-0.51 min) and significantly higher in lactose-free formula (19.57-0.66 min) than in soy protein formula (17.22-0.63 min). The z-values of Cronobacter in reconstituted milk or feeding formula ranged from 4.01 degrees C to 4.39 degrees C. Water heated to > or =70 degrees C and added to powdered milk and formula resulted in a > 4 log(10) reduction of Cronobacter.


CONCLUSIONS
The heat resistance of Cronobacter should not allow the survival of the pathogen during normal pasteurization treatment. The use of hot water (> or =70 degrees C) during reconstitution appears to be an effective means to reduce the risk of Cronobacter in these products.


CONCLUSIONS
This study supports existing data available to regulatory agencies and milk producers that recommended heat treatments are sufficient to substantially reduce risk from Cronobacter which may be present in these products.
Osaili
T M
TM
Department of Nutrition and Food Technology, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, Jordan. tosaili@just.edu.jo
Shaker
R R
RR
Al-Haddaq
M S
MS
Al-Nabulsi
A A
AA
Holley
R A
RA