title: Effect of chlorine, blanching, freezing, and microwave heating on Cryptosporidium parvum viability inoculated on green peppers.
abstract: Cryptosporidium parvum oocysts have been found on the surface of vegetables in both developed and developing countries. C. parvum can contaminate vegetables via various routes, including irrigation water. This study investigated the effect of individual treatments of chlorine,  blanching, blast freezing, and microwave heating, as well as combined treatments of chlorine and freezing, and chlorine and microwave heating on the viability of C. parvum oocysts inoculated on green peppers. The viability of the oocysts after the treatments was assessed using propidium  iodide and a flow cytometer. Based on the propidium iodide staining, the chlorine treatments did not affect the viability of the oocysts. Blast freezing significantly inactivated 20% of the oocysts. Microwave heating and blanching significantly inactivated 93% of oocysts. Treatment with chlorine  followed by blast freezing did not affect the viability of the oocysts significantly. Treatment with chlorine and microwave heating was significantly more effective than microwave heating alone and inactivated 98% of the oocysts. The study indicates that C. parvum oocysts are sensitive  to heat and, to some extent, to blast freezing, but are resistant to chlorine. Therefore, the use of chlorine during vegetable processing is not a critical control point for C. parvum oocysts, and the consumption of raw or minimally processed vegetables may constitute a health risk  as C. parvum oocysts can still be found viable on ready-to-eat, minimally processed vegetables.
authors.affiliation: Department of Food Science, University of Pretoria, Pretoria, 0028, South Africa.
authors.forename: G L M C
authors.initials: GL
authors.lastname: Duhain
authors.forename: A
authors.initials: A
authors.lastname: Minnaar
authors.forename: E M
authors.initials: EM
authors.lastname: Buys
mesh_terms: D000818:Animals; D002212:Capsicum / Q000382:microbiology*; D002713:Chlorine / Q000494:pharmacology; D003257:Consumer Product Safety; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D005511:Food Handling / Q000379:methods*; D005514:Food Irradiation; D016266:Food Parasitology; D005519:Food Preservation / Q000379:methods; D005615:Freezing; D006801:Humans; D008872:Microwaves; D033661:Oocysts / Q000254:growth & development
chemical_list: D002713:Chlorine