Effects of intense pulsed light on Cronobacter sakazakii inoculated in non-fat dry milk

Cronobacter sakazakii is known to have caused life-threatening infections in neonates with a fatality rate of 40–80%. Contaminated powdered food, especially powdered infant formula (PIF), has been epidemiologically linked with these foodborne outbreak infections. Clinical symptoms of C. sakazakii infection include necrotizing enterocolitis, bacteremia, and meningitis. Traditional thermal processing of PIF has been used to kill foodborne pathogens, but it has an undesirable flavor and quality attributes that are unacceptable for industrial usage. Thus, there is a need for new bactericidal technologies for dry powdered foods. In this study, an intense pulsed light (IPL) treatment system was developed, and processing parameters such as relative humidity, environmental temperature, initial water activity, initial temperature, and residence time were evaluated for a bactericidal effect on C. sakazakii in non-fat dry milk (NFDM). The results indicated that a synergistic effect of IPL and an appropriate temperature of ∼57.5 ± 0.7 °C exhibited maximum inactivation of 3.18 log₁₀ CFU/g for C. sakazakii in NFDM with little agglomeration at the initial temperature of 25 °C, at the water activity level of 0.25, and a residence time of 28 s. In addition, significantly higher inactivation was observed when IPL was combined with a vibratory feeder (p < 0.05). No significant change in the amino acid composition, particle physical appearance, and typical volatile compounds were observed after IPL treatment. Overall, the study demonstrates that IPL treatment is promising for inactivation of C. sakazakii in NFDM with minimal quality degradation.