Effect of γ-irradiation and food additives on the microbial inactivation of foodborne pathogens in infant formula

The aim of this study was to assess the effect of gamma-irradiation on the microbial inactivation of selected foodborne pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli 0157:H7, and Salmonella Typhimurium) in combination with 2.5% sodium citrate, 0.5% sodium carbonate and 0.75% citric acid as food additives in frozen and powdered infant formula (IF). The study demonstrated that gamma-irradiation alone was more efficient against pathogens in frozen IF. A hurdle technology with sodium carbonate induced a high radio-sensitization in powdered and frozen IF against all pathogens, compared to other additives that induced a lower radiosensitization effect. Contrarily to other pathogens, spore-producing B. cereus was more radiosensitized in powdered IF by carbonate, citrate, and citric acid, with radiosensitivity values up to 4.1. E. coli was strongly radiosensitized in presence of carbonate and citrate in frozen IF with values up to 2.4. This study demonstrated that the use of food additives - mainly sodium carbonate - in combination with gamma-irradiation can be a good way to reduce the time of irradiation treatment to assure the safety of the IF product.