Microscopic organisms are everywhere. Even in places where you would think they are not. Like clean clothes, clean kitchen counters or even washed utensils. Remember those advertisements which claim that they kill 99.9% bacteria. You might think still 0.1% are left there even after using antibacterial disinfectants. In Ontario, they have a standard that on a cleaned utensil there should not be more than 100 bacterial colonies! Imagine what happens to utensils cleaned by us in dishwashers which does not even use those kinds of disinfectants! A study was done by scientists in Ontario, Canada on the dishwashers which did not handle a lot of utensils at an instance. So if you are living in a family daycare services, or residential care home, this article is for you. Along with disinfectants, high temperature is also needed to kill microorganisms which the dishwashers actually use. But in places where the utensils are not that much, the dishwashers cannot achieve that temperature. Also, if low temperature is used to treat utensils then sanitizer has to be used at a set time and concentration but normal dishwashers do not have this function. So, if you live in any of these places then you might ask that they install a commercial sized dishwasher instead of domestic dishwasher. The study found that 83% of these dishwashers actually worked within the prescribed limits but still there are 17%, that is, more than 1 out of 6 instances that your utensils are actually not clean and contain a lot of unwanted stuff.
This paper aimed at the study of cleaning ability of domestic dishwashers employed in residential care homes. The researchers picked these places because they know that dishwashers do not work that good if there are less utensils cleaned at a time. This happens due to low temperature that water reaches when cleaning occurs. A temperature of 82oC for 10 seconds or chemical sanitization at 24oC is required to properly sanitize the utensils. For samples, they chose 4 establishments with different number of dishwashing units to a total of 103 units. 4 different types of utensils were selected for the study and were swabbed after one full cycle was over. Standard operating procedures laid out by United States Public Health Service’s (USPHS) were followed. Of the 103 domestic dishwashers evaluated, 85 (83%) yielded results that fell within the prescribed limit of no more than 100 bacterial colonies per utensil as determined by heterotrophic plate count (HPC). Dishwashers that contained utensils classified as somewhat soiled or very soiled before washing were more likely to fail (P < 0.05) than those that were classified as very clean or somewhat clean before washing, when all other characteristics and operating parameters and the number of plastic items were controlled for. With increasing maximum rinse temperature, dishwashers were less likely to fail (P < 0.05) while the same characteristics were controlled for. Also, dishwashers were more likely to fail when chlorinated detergents were used (P < 0.05).