Inactivation of Salmonella Enteritidis on cherry tomatoes by ultrasound, lactic acid, detergent, and silver nanoparticles.

Ultrasound (US) combined with chemical agents could represent an effective method for decontaminating fruits and vegetables. This study aimed to evaluate the use of US (40 kHz for 5 min) alone or with 1% lactic acid (LA), 1% commercial detergent (DET), or 6 mg/L silver nanoparticles (AgNP, average diameter 100 nm) as an alternative treatment to 200 mg/L sodium dichloroisocyanurate for inactivating Salmonella enterica serovar Enteritidis present on cherry tomatoes. The interfacial tension between sanitizing solutions and bacterial adhesion was investigated. Sanitizers in solutions with DET and AgNP had lower surface tension. All treatments, except that with DET, reduced Salmonella Enteritidis by more than one logarithmic cycle. There was no significant difference between the mean values of log colony-forming units (CFU)/g reduction in all treatments. Transmission electron microscopy revealed the loss of the Salmonella Enteritidis capsule following treatment with US and with US + LA. Salmonella Enteritidis counts (2.29 log CFU/g) in cherry tomatoes were markedly reduced to safe levels by treatment with the combination of AgNP and US + LA (2.37 log CFU/g).