Effect of Chlorine, Blanching, Freezing, and Microwave Heating on Cryptosporidium parvum Viability Inoculated on Green Peppers

2012 ◽  
Vol 75 (5) ◽  
pp. 936-941 ◽  
Author(s):  
G. L. M. C. DUHAIN ◽  
A. MINNAAR ◽  
E. M. BUYS
Keyword(s):  
Microwave Heating ◽  
Cryptosporidium Parvum ◽  
Propidium Iodide ◽  
Control Point ◽  
Minimally Processed ◽  
Critical Control Point ◽  
Propidium Iodide Staining ◽  
Cryptosporidium Parvum Oocysts ◽  
Minimally Processed Vegetables ◽  
Effect Of Chlorine

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.

Microwave Inactivation of Cyclospora cayetanensis Sporulation and Viability of Cryptosporidium parvum Oocysts

2006 ◽  
Vol 69 (8) ◽  
pp. 1957-1960 ◽  
Author(s):  
YNES R. ORTEGA ◽  
JYEYIN LIAO
Keyword(s):  
Cryptosporidium Parvum ◽  
Propidium Iodide ◽  
Cryptosporidium Oocyst ◽  
Cooking Time ◽  
Cyclospora Cayetanensis ◽  
The Third ◽  
Infectivity Assay ◽  
Cryptosporidium Oocysts ◽  
Cryptosporidium Parvum Oocysts ◽  
Cooking Times

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 neonate 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.

Fate of Staphylococcus aureus in Beef Loaf, Potatoes and Frozen and Canned Green Beans after Microwave-Heating in a Simulated Cook/Chill Hospital Foodservice System1

1980 ◽  
Vol 43 (12) ◽  
pp. 916-923 ◽  
Author(s):  
C. A. DAHL ◽  
M. E. MATTHEWS ◽  
E H. MARTH
Keyword(s):  
Staphylococcus Aureus ◽  
Microwave Heating ◽  
Hazard Analysis ◽  
Control Point ◽  
Food Samples ◽  
Green Beans ◽  
Critical Control Point ◽  
Before And After ◽  
The Mean

The fate of Staphylococcus aureus in cook/chill systems before and after microwave-heating was determined, using inoculated beef loaf, dehydrated potatoes and frozen and canned green beans. These foods were prepared according to time and temperature recommendations of the Hazard Analysis Critical Control Point (HACCP) model for hospital cook/chill systems. Beef loaf was initially cooked to a mean end temperature (ET) of 66 C, potatoes were rehydrated and heated to a mean ET of 79 C and beans were not cooked initially. Products were covered and stored 24 h at 6 C. Products were portioned, 100 g/portions, stored covered 2 h at 6 C, and microwave-heated: beef loaf and frozen beans 20, 50, 80 or 110 sec; potatoes 25, 45, 65 or 85 sec and canned beans 20, 40, 60 or 80 sec. Number of S. aureus in products decreased as time of microwave-heating increased. When the mean ET of samples was approximately 74–77 C (HACCP model), microwave-heating did not consistently result in lethality of S. aureus. When time of microwave-heating in the present study was equal to time to reach 74–77 C in the prestudy, an ET of 74–77 C did not consistently occur in the food samples.

scholarly journals Effect of Batch-Process Solar Disinfection on Survival of Cryptosporidium parvum Oocysts in Drinking Water

2005 ◽  
Vol 71 (3) ◽  
pp. 1653-1654 ◽  
Author(s):  
F. Méndez-Hermida ◽  
J. A. Castro-Hermida ◽  
E. Ares-Mazás ◽  
S. C. Kehoe ◽  
K. G. McGuigan
Keyword(s):  
Drinking Water ◽  
Standard Deviation ◽  
Cryptosporidium Parvum ◽  
Propidium Iodide ◽  
Batch Process ◽  
Simulated Sunlight ◽  
Solar Disinfection ◽  
Suckling Mice ◽  
Cryptosporidium Parvum Oocysts

ABSTRACT The results of batch-process solar disinfection (SODIS) of Cryptosporidium parvum oocysts in water are reported. Oocyst suspensions were exposed to simulated sunlight (830 W m−2) at 40°C. Viability assays (4′,6′-diamidino-2-phenylindole [DAPI]/propidium iodide and excystation) and infectivity tests (Swiss CD-1 suckling mice) were performed. SODIS exposures of 6 and 12 h reduced oocyst infectivity from 100% to 7.5% (standard deviation = 2.3) and 0% (standard deviation = 0.0), respectively.

Inactivation of Cryptosporidium parvum oocysts and other microbes in water and wastewater by electrochemically generated mixed oxidants

2000 ◽  
Vol 41 (7) ◽  
pp. 127-134 ◽  
Author(s):  
M. J. Casteel ◽  
M. D. Sobsey ◽  
M. J. Arrowood
Keyword(s):  
Escherichia Coli ◽  
Cell Culture ◽  
Cryptosporidium Parvum ◽  
Propidium Iodide ◽  
Treated Wastewater ◽  
E Coli ◽  
Water And Wastewater ◽  
Cryptosporidium Parvum Oocysts ◽  
Cell Culture Assay ◽  
Escherichia Coli B

Alternative disinfectants of water and wastewater are needed because conventional chlorination is ineffective against C. parvum oocysts. Reliable indicators of disinfection efficacy against C. parvum also are needed. Mixedoxidants (MO) electrochemically generated from brine were evaluated in batch disinfection experiments for inactivation of C. parvum oocysts and Cl. perfringensspores in both oxidant demand-free (ODF) water and treated wastewater. Coliphage MS2 and Escherichia coli B were also tested under some conditions. C. parvum oocyst infectivity was quantified by cell culture assay, and the dyes DAPI (4′,6-diamidino-2-phenylindole) and propidium iodide (PI) were used to assess oocyst viability in wastewater experiments. In treated wastewater dosed with 10–13 mg/L MO, inactivation after 90 minutes was about 3 log10 for C. parvum and about 2.5 log10 for Cl. perfringens spores; MS2 and E. coli were rapidly inactivated by > 5 log10. In ODF water, a 4 mg/L dose of MO inactivated ∼3 log10 of C. parvum oocysts and ∼1.5 log10 of Cl. perfringens spores. Inactivation of C. parvum oocysts and Cl. perfringensspores was less extensive at a lower MO dose of 2 mg/L. The use of DAPI and PI to determine viability of oocysts treated with MO did not correlate with, and greatly overestimated, cell culture infectivity. At practical doses and contact times, MO disinfection of water and wastewater achieves appreciable inactivation of both C. parvum oocysts and Cl. perfringens spores. Cl. perfringens spores reliably indicated oocyst inactivation by MO, but E. coli and coliphage MS2 were inactivated much too rapidly to indicate C. parvum inactivation.

Depressed filtration ripening enhances removal of Cryptosporidium parvum

2002 ◽  
Vol 2 (3) ◽  
pp. 159-168 ◽  
Author(s):  
V. Gitis ◽  
R.C. Haught ◽  
R.M. Clark ◽  
E. Radha Krishnan
Keyword(s):  
Surface Water ◽  
Cryptosporidium Parvum ◽  
Pilot Scale ◽  
Kaolin Clay ◽  
Clay Particles ◽  
Physico Chemical ◽  
Cryptosporidium Parvum Oocysts ◽  
Granular Filtration ◽  
Electrostatic Adhesion ◽  
Innovative Concept

Pilot-scale experiments were conducted to investigate removal of Cryptosporidium parvum by contact granular filtration. The research demonstrated enhanced removal of Cryptosporidium parvum in the presence of kaolin particles. This is believed to be due electrostatic adhesion of Cryptosporidium parvum oocysts to the kaolin clay particles. The elementary physico-chemical interactions between filter granules and suspension particles will be discussed. This innovative concept was successfully implemented to reduce the ripening sequence of subsequent filtration experimental test runs by the addition of large surface area particles to slurry of kaolin and Cryptosporidium parvum in surface water.

Survival of giardia, cryptosporidium, poliovirus and salmonella in marine waters

1997 ◽  
Vol 35 (11-12) ◽  
pp. 261-268 ◽  
Author(s):  
D. C. Johnson ◽  
C. E. Enriquez ◽  
I. L. Pepper ◽  
T. L. Davis ◽  
C. P. Gerba ◽  
...  
Keyword(s):  
Water Quality ◽  
Salmonella Typhimurium ◽  
Cryptosporidium Parvum ◽  
Common Method ◽  
Waterborne Pathogens ◽  
Protozoan Parasites ◽  
Marine Waters ◽  
Untreated Sewage ◽  
Cryptosporidium Parvum Oocysts ◽  
Giardia Muris

Discharge of sewage into the ocean is still a common method of disposal worldwide. Both treated and untreated sewage may contain significant concentrations of waterborne pathogens, such as Giardia, Cryptosporidium, poliovirus and Salmonella. Limited studies exist on the survival of poliovirus and Salmonella in marine waters; however, almost no information exists on the survival of protozoan parasites in marine waters. This study examined the survival of Giardia muris cysts, Cryptosporidium parvum oocysts, poliovirus-1 and Salmonella typhimurium in marine waters. The survival of the microorganisms varied according to the presence of light, salinity and water quality (as determined by quantity of enterococci). All microorganisms survived longer in the dark than in sunlight, the order of survival in sunlight being: Cryptosporidium > poliovirus > Giardia > Salmonella.

Sign in / Sign up

Export Citation Format

Share Document