Comparative Studies on the Novel Sterilisation of Irish Retailed Infant Milk Formula Using Electron Beam and Pulsed Light Treatments

This constitutes the first study to compare use of electron beam (EB) irradiation and pulsed light (PL) for novel sterilisation of infant mik formula retailed in Ireland. The microbiological quality of 60 powdered infant milk formula (PIMF), representative of two leading brands available in Ireland, were analyzed immediately after reconstitution and were shown to exhibit a total aerobic mesophilic count of <10 4 CFU/g (mean 3.3 x10 2 CFU/g) and a Bacillus cereus count of <10 3 CFU/g powder (mean 2.2x10 2 CFU/g). Only 7 of 60 PIMF samples of Irish PIMF were free of Bacillus sp; while the pathogenic bacteria Cronobacter sakazakii and Listeria monocytogenes were not detected in any samples. Application of EB irradiation at 10 kGy sterilised the aforementioned PIMF. Pulsed light was not suitable for PIMF sterilisation due to turbidity, but did successfully kill C. sakazakii, L. monocytogenes and test Bacillus species when suspended and treated in saline solution. D10 values [dosage required to elicit a one log10 reduction in microbial numbers], for EB varied over the range 1.4 to 2.5 kGy for Bacillus species treated. Nutritional studies of EB-treated of PIMF samples at upper 10 kGy revealed no discernible difference in appearance, moisture, protein, ash, vitamin C, total fat and total carbohydrate content compared with untreated controls. The results indicate that EB treatment of Irish retailed infant milk formula at 10 kGy destroyed Bacillus endospores in these products without affecting nutritional status or appearance.