Inactivation efficacies of lactic acid and mild heat treatments against Escherichia coli strains in organic broccoli sprouts

The kinetics of the inactivation of Escherichia coli in organic broccoli sprouts by mild heat (MH) and lactic acid (LA) were investigated. In vitro survival kinetics showed that the cell number decreased dramatically and was not detectable after 120–135 s under combination treatment. Protein leakage and atomic force microscopy analyses showed that inactivation of E. coli cells resulted from disruption of the outer membrane by the sanitisers. LA almost destroyed the outer membrane and induced high protein leakage (3.78–10.75 μg/mL). MH enhanced the membrane damage caused by LA. The in vivo inactivation and following recovery during storage suggested that the combination treatment presented a potential inactivation process for organic vegetables or sprouts. Weibull model with higher R2 values (0.66–0.99) best described the in vitro antibacterial kinetics and in vivo recovery dynamics. Moreover, the metabolic analysis revealed that citrate cycle (TCA) and amino acid metabolism contributed to the adaptive responses.