A method to evaluate factors influencing the microbial reduction in domestic dishwashers

Abstract

Aims:To develop a method that is able to determine the microbial reduction in different dishwasher cleaning cycles and differentiate between different program parameters used. Methods and Results: Stainless steel biomonitors were contaminated with Micrococcus luteus or Entereococcus faecium and cleaned in a specially programmed household dishwasher with different cleaning temperatures and durations. No detergent, bleach-free detergent or detergent containing activated oxygen bleach was used. The logarithmic reduction (LR) was determined. The microbial reduction depended on the cleaning temperature, the duration of the cleaning cycles and the detergent type used. LR increased with higher temperatures, longer cleaning cycles and use of detergent. Conclusions: The factors cleaning cycle temperature, cleaning cycle duration, final rinsing temperature and the use of detergent all contributed to the reduction of test-strains in dishwasher cycles. A combination of longer dishwashing cycles and increased temperatures resulted in LR max of the microbial load. Significance and Impact of the Study: Cycles in domestic appliances are very diverse; therefore a standardized method to determine their ability to reduce the microbial load is of great use. The method described here is able to demonstrate the reductions achieved by dishwashing cycles with different parameters and might help to find the necessary balance between energy saving and an acceptable level of hygiene.

Assessing the Removal Efficiency of Murine Norovirus 1, Hepatitis A Virus, and Human Coronavirus 229E on Dish Surfaces Through General Wash Program of Household Dishwasher

“…The logarithmic reduction in Table 2 was determined according to follow the equation (Brands et al, 2020 ): Logarithmic reduction = log 10 (initial virus load) − log 10 (remaining virus load). Moreover, the reduction ratio (%) was calculated = (recovered virus or genome copies of the process Control − recovered virus or genome copies of the Treatment − LOD value of each virus)/(recovered virus or genome copies of the process Control − LOD value of each virus) × 100 (Fig.…”

“…The popularity of automatic dishwashers in households has increased and they are rapidly replacing manual washing, owing to their superior performance in effectively removing food residue particles in recent years (Rahman, 1985 ; Vivian et al, 2011 ). Meanwhile, longer cycles, combined wash programs, and high-operating temperatures also reduce the microbial load, thus maintaining a sufficient hygiene level on the food contact surface of the tableware (Brands et al, 2020 ). However, little research has been conducted on virus contaminant removal using household dishwashers.…”

Dishwashers: Literature Review to Summarise the Multi-Dimensionality of Sustainable Production and Consumption

“…While on detergents, it must be mentioned that Brands and fellow researchers [68] managed to prove that, while it is a combination of three factors-time, temperature, and type of detergent-that determines the extent of microbial reduction, activated oxygen bleach (AOB) detergent (non-chlorinated) performed slightly better than its chlorinated counterpart. AOB was also shown to be effective against antibiotic-resistant species such as methicillin-resistant Staphylococcus Aureus [69].…”

“…AOB was also shown to be effective against antibiotic-resistant species such as methicillin-resistant Staphylococcus Aureus [69]. As AOB is slower acting than chlorinated alternatives, a longer time and a higher temperature is usually needed to compensate for the slowness [68], though Rehberg and colleagues in [69] have stated that it has the ability to inactivate resistant bacteria even at lower temperatures. The chlorine in detergents, residual chlorine, and disinfection byproducts in the wash/rinse water tend to interact with soluble proteins in food particles on the dishes and form trihalomethanes, which are released into both the greywater and the atmosphere (from the dishwater headspace) [53].…”

The Household Resistome: Frequency of β-Lactamases, Class 1 Integrons, and Antibiotic-Resistant Bacteria in the Domestic Environment and Their Reduction during Automated Dishwashing and Laundering

“…This effect should apply for antibiotic resistant bacteria as well, since no significant differences between susceptible and resistant strains during laundering were obtained. The dishwasher sump and rubber seal provide good conditions for microbial growth while the walls only reveal low contaminations (40,49,55). Therefore, it can be assumed that dishes cleaned in the dishwasher show similar amounts of bacterial load.…”