[Effects of sodium chloride on destruction of microorganisms by microwave heating in potatoes]

To assess the destructive effect of different sodium chloride concentrations (0, 0.3, 1.5, and 3%) on microorganisms with microwave heating, strains of Vibrio parahaemolyticus, Staphylococcus aureus, Salmonella enteritidis, Escherichia coli and Bacillus cereus were used to inoculate a mashed potato preparation. After microwave heating for 1 min at 800 W, resulted in temperatures and rate of destruction of bacteria significantly higher (p less than 0.05) in the core than on the surface of mashed potato when no salt was added. Except for B. cereus, microorganisms inoculated into mashed potato, with no added salt, could be completely destroyed by 2 min of microwave heating. Core temperatures and rate of destruction of microorganisms in the mashed potato decreased significantly (p less than 0.05) with increase in concentration of added salt. The results also indicate that bacterial species differ in their susceptibility to microwave inactivation. In particular, S. aureus, which exhibited a level of survival that was greater than that of any other species tested here, seemed notably resistant to microwave treatment for 2 min while V. parahaemolyticus was highly susceptible.