Preservation by the Lactoperoxidase system (LP-S) of a contaminated infant milk formula

Enterococcus, Pseudomonas spp. and Enterobacteriaceae did not grow in an infant milk formula inoculated with the mixed flora contained in lake water and supplemented with an activated lactoperoxidase system (LP‐S). Yeasts did grow and, with the exhaustion of thiocyanate (SCN‐) after 48 h, the one which had attained numerical dominance, Rhodotorula glutinis, was displaced by a non‐pigmented yeast. The growth of the bacteria mentioned above occurred along with that of the latter yeast. Absence of the LP‐S from the infant milk was associated with the unrestricted proliferation of Enterobacteriaceae in general and Escherichia coli in particular. These organisms dominated the microbial population after 24 h storage. The LP‐S also prevented significant glucose utilization and stabilized the pH.