Combined effect of low energy X-ray irradiation and natural antibacterial formulation for decontamination of mother's milk

Human milk in milk banks is prone to contamination by foodborne pathogens at many stages, from collection to packaging and storage. The objective of the study was to evaluate the bactericidal effect of an antibacterial formulation (AF; 0.025 % v/v) combined with X-ray irradiation up to 2 kGy (acceleration voltage of 55 kV; low voltage (LX) or 350 kV; high voltage (HX)) on vegetative cells of B. cereus, S. aureus and C. sakazakii in frozen milk. The D10 values in HX-ray treatment were 0.367, 0.410, and 0.205 kGy for B. cereus, S. aureus and C. sakazakii, respectively, and 0.384, 0.445, and 0.232 for LX-ray treatment. The addition of AF in human milk increased radiosensitivity (RS) of pathogens, with a higher RS value recorded in LX-ray treatment against B. cereus, and S. aureus (1.47 and 1.37) compared to 1.43 and 1.26 in HX-ray irradiated samples. The effect of the combined treatment on physicochemical attributes of milk samples was evaluated. The combined treatments didn't affect significantly lactose content, lipid oxidation, viscosity and color parameters, with better stability of these parameters in LX-ray treated samples compared to HX-ray treated samples at higher doses (1 and 2 kGy). The results obtained showed potential applicability of low energy X-ray in combination with AF as innovative antimicrobial non-thermal intervention that may be used human milk decontamination.