Most institutions (such as restaurants) have a dish washing machine which sanitizes dishes by a final rinse in either very hot water or a chemical sanitizing solution (e.g. bleach solution). Dishes are placed on large trays and fed onto rollers through the machine. The bleach solution is quite dilute (50-100 parts per million chlorine which is approximately one cap full of bleach per gallon water). Ohio State University researchers recently tested the merits of two new dishware sanitizers, and found them more effective at removing bacteria from restaurant dishes than traditional sanitizers. The two sanitizers — one carrying the name brand PROSAN® and the other called neutral electrolyzed oxidizing water — not only proved more effective, but they also contained fewer toxic chemicals.
The new research can be found in the January 2011 issue of the journal Food Control.
"Longer lasting sanitizers could be more cost effective for restaurants because they would not have to use nearly as much sanitizing solution as they currently do," said Pascall, one of the authors. "We cannot provide an estimate comparing the cost per volume between the four sanitizers, however."
Traditional sanitizers used by restaurants contain chemicals such as bleach, which can corrode dishware, damage the environment, and irritate or burn the skin. Such sanitizers also lose their effectiveness with each additional washing cycle. This means that the killing agents within the sanitizers kill fewer amounts of harmful bacteria with each rinse.
E. coli outbreaks have been on the decline since 2002, but food is still the primary means for food borne illness transmission. The Centers for Disease Control and Prevention (CDC) estimated that 28 percent of food borne outbreaks between 1982 and 2002 originated from restaurants or other public food establishments.
The research compared the effectiveness of four different sanitizers by contaminating samples of milk and cream cheese with the highly infectious bacteria E. coli, and Listeria innocua. They chose four sanitizers: PROSAN®, a neutral electrolyzed oxidizing water, an ammonia compound, and sodium hypochlorite.
The neutral electrolyzed oxidizing water contained a bacteria-killing agent called hypochlorous acid, and it had an electrical potential different from that of tap water. The combined action of these two agents was responsible for the microbial reduction obtained during the study. One good point about using this water to clean dishes is that it has a neutral pH range of 6.5 to 7.5. A neutral pH means the sanitizer will not corrode dishes as much as highly acidic or alkaline sanitizers.
The researchers used three different types of dishware, plastic trays, ceramic plates, and glass cups. After covering the dishware with the infected milk or cream cheese, they let the food air dry for one hour before washing them.
The FDA Food Code states that the amount of bacteria on a surface needs to be at least 100,000 times less after washing compared to before washing in order for it to be considered clean. This can be referred to as 5-log reduction.
The researchers tested multiple dirty loads with the same batch of sanitizer to see how many loads they could wash and still have a 5-log reduction of bacteria.
When the researchers were washing loads of glass dishes, the electrolyzed water and the PROSAN® sanitizers lasted 19 washing cycles, whereas the ammonia compound and the sodium hypochlorite were only as effective over 17 washing cycles. Similar results were found with ceramic dishes.
There are many different ways to wash dishes that are all aimed at reducing infectious disease.
In Indonesia, dishwashing is done by scrubbing the utensils with wet fabric dipped in scrub ash to scrub away the dirt. The utensils are then rinsed in clean water and hung to drip dry. In some European countries, the dishes are generally washed in a separate tub placed inside the sink. This practice may have started as a matter of hygiene, as the kitchen sink was the only sink available for all the household water. The clothes were washed in the sink; the water used to wash the floor went down the sink, and so it made sense to separate the dishwater from the sink.
Cost,effectiveness, as well as perceived effect and quality are all aspects of dishwashing.
For further information: http://en.wikipedia.org/wiki/Dish_sanitizing or http://researchnews.osu.edu/archive/sanitizer.htm