Microwave inactivation of Cyclospora cayetanensis sporulation and viability of Cryptosporidium parvum oocysts

Abstract

The efficacy of microwave heating on the viability of Cryptosporidium parvum oocysts and on the sporulation of Cyclospora cayetanensis oocysts for various periods of cooking times (0, 10, 15, 20, 30, and 45 s) at 100% power was determined. Cyclospora oocysts were stored in 2.5% dichromate at 23°C for 2 weeks, and sporulation rates were then determined. The 4′,6-diamidino-2- phenylindole and propidium iodide vital stain and the neonale animal infectivity assay determined Cryptosporidium oocyst viability. Cryptosporidium oocysts could be completely inactivated with as little as 20 s of cooking time, whereas Cyclospora sporulation was observed up to 45 s. Two of the examined microwave ovens were more effective at reducing sporulation and viability than the third one. Because of the variability of temperature achieved by the various ovens, cooking time was not an accurate parameter for parasite inactivation. Cryptosporidium oocysts could be inactivated only when temperatures of 80°C or higher were reached in the microwave ovens. Copyright ©, International Association for Food Protection.