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Effect of Bifidobacterium breve on the growth of Enterobacter Sakazakii in rehydrated infant milk formula

Osaili, T.M., Shaker, R.R., Ayyash, M.M., Holley, R.A.
Journal of food safety 2008 v.28 no.1 pp. 34-46
Cronobacter sakazakii, infant formulas, reconstituted milk, food biopreservation, food biopreservatives, Bifidobacterium breve, lactic acid bacteria, probiotics, food storage, storage temperature, storage time, food pathogens, bacterial contamination, competitive exclusion
The effect of Bifidobacterium breve on the survival and growth of Enterobacter sakazakii in rehydrated infant milk formula stored at 4-45C was studied. A commercial culture of B. breve and a five-strain cocktail E. sakazakii were mixed with rehydrated formula and stored up to 8 h. The populations of B. breve and E. sakazakii at each storage time/temperature were determined. There was a two-way interactive effect between B. breve numbers and temperature on the number of E. sakazakii in the rehydrated formula at 3-8 h of storage. E. sakazakii did not grow in the rehydrated formula at 4C. At 12 and 20C, the numbers of E. sakazakii in the presence of B. breve were lower than those in the formula without B. breve at 8 h of storage, and at 45C, when the bacteria were combined, a similar result was obtained at 6- and 8-h storage. The presence of B. breve in the formula appeared to enhance the growth of E. sakazakii at 37C in the rehydrated formula stored at 2-8 h. Other more competitive inhibitory probiotic cultures would be more appropriate to control E. sakazakii growth in unrefrigerated rehydrated milk-based formula. Results obtained showed that the probiotic organisms Bifidobacterium breve did not reduce Enterobacter sakazakii levels in rehydrated infant formula if held >2 h at >30C. At 37C, B. breve stimulated the growth of the pathogen after 2 h. Choice of probiotic bacteria for inclusion in these products to improve infant gut microflora should be based on their neutral or negative influence on E. sakazakii survival/growth to reduce the risk to health associated with the contamination of these products during manufacture.