In times of low-temperature washing, laundry hygiene gains importance, as microbial contaminations on textiles can cause infection transmission and malodour formation. This study systematically investigated the antimicrobial effect of laundry detergents (solid and liquid market detergents) with regard to time and temperature in domestic washing machines. To evaluate the microbial reduction, cotton swatches contaminated with Staph. aureus, Ent. hirae, Ps. aeruginosa, C. albicans and T. mentagrophytes were washed at 20 to 60 °C, varying the washing time, with and without detergent. All tested washing factors affected the antimicrobial effect of to a varying extend, depending on the germ. The used solid market detergent containing activated oxygen bleach provided a way to achieve high microbial reductions in low temperature washing.

It is known that decreasing temperatures in laundry can have a significant impact on the hygiene efficacy of laundering. This study used suspension tests to investigate the microbicidal effects of heat, detergent and activated oxygen bleach and their contributions to laundry hygiene. The results indicate that heat at 60°C contributes significantly to the microbicidal action, while detergent only has limited effects. Activated oxygen bleach strongly enhances the microbicidal action and thus has the potential to compensate for the loss of antimicrobial efficacy due to temperature decrease. This effect varied with the test strain and the temperature, and further work is needed to determine whether it is possible to achieve a hygiene effectiveness equivalent to that at 60°C across both fungal and bacterial strains.

Rising environmental concerns lead to use of lower temperatures and to reduced water consumption in domestic dishwashing. The development of new dishwashers with reservoir for reusage of water from the final rinse seeks to reduce the costs per cleaning cycle, but leads to concerns about the hygienic conditions of domestic dishwashers, as the presence of stable communities of microorganisms has been reported. This study investigates the hygienic conditions of different types of domestic dishwashers and the long-term effect of process parameters on the hygiene in dishwashers with water reservoirs.

The proper cleaning of used dishes provides an essential means to maintain a sufficient hygiene level on food contact surfaces. However, little is known on the microbiological quality of domestic dishwashers themselves, especially in relation to consumer habits. This study investigated dishwashers in German households to analyse the number and composition of microbial colonisers and their putative impact on dishwashing hygiene. Although the microbiological status of dishwashers appeared to depend on multiple factors, data suggest that a trend towards lower temperatures might effect in a decreased hygiene.

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.