General Electric and Whirlpool don’t.
The phenomenon of dishwasher cooking, recently explored in an article by NPR Reporter Michaeleen Doucleff, has enjoyed exposure on blogs and in major news organizations. However, very little data exist to guide discussions on the safety of the practice.
Casali, an Italian food author who has written a book on the subject of dishwasher cooking, spent some time studying the safety of the practice. Before writing “Cucinare in Lavastoviglie” (“Cooking in the Dishwasher”), she had an Italian chemical laboratory analyze samples of food cooked in various containers in a dishwasher. She said that the results showed that food cooked in vacuum-sealed plastic bags or hermetically sealed jars doesn’t risk contamination from the water or detergent used in the dishwasher.
However, that’s not the only concern about the practice for North Carolina State University food specialist Ben Chapman. There’s also the question of whether dishwashers heat up the food enough to kill pathogens such as Salmonella enteritidis and clostridium botulinum.
“I have no idea what temperature my dishwasher reaches,” Chapman said. “That matters here because, with fish, the recommended endpoint temperature is 145 degrees Fahrenheit.”
Casali said Electrolux representatives told her that the dishwashers she used while researching for her book reach 131-167 degrees F.
Chapman said the scientific literature provides specific cooking temperatures to make specific foods such as poultry, beef, pork and fish safe to eat, much in the 145 to 160 degree range. But, especially for eggs, the dishwasher would need to reach some of its highest temperatures to ensure that any pathogens in the food were destroyed. For fruits, vegetables and food that can be eaten raw, he said that cooking temperature might be less of a problem.
Chapman’s concern with C. botulinum involves food being left in a sealed space for an extended period of time. He said that the best environment for the bacterium’s cells to vegetate in is one of less than 240 degrees F with little or no oxygen.
“We’ve seen outbreaks of botulism from the environment people have created in their home, where they can their food, then leave it in their pantry for weeks,” Chapman said.
Using a dishwasher over cooker for canning (or preserving) also concerns Chapman because, although boiling water (212 degrees) will kill vegetative cells, it is not enough to kill inactive spores. Cookers for canning reach 240 degrees for canning and other processes because they inactivate the spores.
Less heat than that in an environment without oxygen can result in spores germinating and outgrow resulting in vegetative cells. Chapman said a byproduct of cell multiplication is toxin.
“So you need to get to 240 to inactivate the spores – or once they are vegetative,” he said.
U.S. Food and Drug Administration spokesman Sebastian Cianci said he could find no reports of illness related to dishwasher cooking, although he said cooking methods might not be included in such statements.
Casali stressed that dishwasher cooking isn’t the only time people are served food prepared at low temperatures.
“Cooking at low temperature is a popular technique in restaurants and … every day [such dishes] are served [by the] thousands,” she said.
However, Chapman cautioned that people who are at high risk of contracting a foodborne illness – groups such as the young, old, pregnant women and those whose immune systems are compromised – could be putting themselves in danger by eating meals cooked at low temperatures.
“If somebody’s going through chemotherapy, if someone’s been advised because of some other health condition that they shouldn’t be eating raw vegetables or raw foods, it could be a risky proposition,” he said.
Representatives from General Electric and Whirlpool said that they didn’t recommend using their dishwashers to cook food.
“Dishwashers are not intended to cook food. They are designed to clean dishes,” said Kim Freeman, a spokeswoman for General Electric.
Samantha Smitala, a spokeswoman for Whirlpool, said the company advises its customers to use their products according to their use and care guides.
One Whirlpool dishwasher care guide states, “Use the dishwasher only for its intended function.”
Chapman, who contributed to food-safety website BarfBlog.com, said he hopes to conduct some testing soon on dishwasher cooking because there isn’t very much scientific information available on the practice right now.
“I don’t think we know enough about cooking in the dishwasher to really, truly assess the risk,” he said.© Food Safety News