Method to evaluate the antimicrobial efficacy of domestic laundry detergents
During the last decades, the strive for energy efficiency lead to lower washing temperatures in laundering processes. In this regard, there is a rising need to measure the antimicrobial action of laundry detergents and additives, since chemistry must be considered an important means to compensate for the loss of temperature. Although there is an existing standard method (EN 16616) to evaluate the antimicrobial efficacy of detergents for the medical area, this method does not reflect the domestic situation and neglects important steps, such as the rinse cycles.
Experimental setup represents whole washing process
Now researchers developed an experimental setup, which represents the whole washing process and reflects the domestic situation by using a household‐related setting. The suggested method uses a lab‐scale washing machine, which does not only allow to test products that can be applied throughout the whole laundering process (including the rinse steps) but also proved to be able to show the impact of different parameters (e.g., detergent ingredient or different types of textiles) in a very systematic manner.
This study showed that a lab‐scale washing machine is suitable to simulate domestic laundering processes and can be used to investigate parameters influencing the antimicrobial efficacy of one washing process. In a domestic washing machine, it is difficult to separately evaluate the impact of the four factors of the Sinner’s principle time, temperature, mechanical action, and chemistry. Moreover, overlapping effects of other parameters, such as overdosing or underdosing of the detergent by the consumer, the type of soil ballast (e.g., sheep blood or BSA), ballast load, embedding matrix or the biomonitors are almost impossible to be kept apart in a washing machine and can be investigated easily in a lab‐scale device.
More studies needed
With the lab scale washing machine, the results for the main wash mostly confirm previous studies using a domestic washing machine. Nevertheless, further work might help to better understand the methodological correlations and limitations, especially with regard to the rinse cycle, which has not been investigated comprehensively in the washing machine yet.
The study has been published in Journal of Surfactants and Detergents