Cronobacter sakazakii Inactivation by Microwave Processing

Nowadays, current practices at home and childcare settings involved MW heating after powder infant formula milk reconstitution. Microwave (MW) effectiveness for Cronobacter sakazakii inactivation in reconstituted powder infant formula milk was investigated. Power levels in the range 400-900 W were tested during exposure times ranging from 0 to 120 s. Power levels of 800 and 900 W reduced the C. sakazakii initial population to undetectable levels (≥8 log₁₀ cycles), reaching maximum temperatures of 78.8 ± 2.3 °C and 88.1 ± 1.5 °C, respectively. A post-treatment storage study (5 °C, 24 h) was completed to determine the recovery or death of C. sakazakii damaged and survival cells. It was observed that lowest MW intensity treatments (power level and treatment time) provide the highest percentages of injured cells. Moreover, these high percentages of damaged cells progressively die during refrigerated storage (up to 24 h). Microbial reduction levels higher or equal to 5 log₁₀ cycles were reached due to the sublethal damaged cell death.