Researchers discover a new way to assess the effectiveness of cleaning products

Environmental awareness in society is changing household laundry habits, where the use of less bleach and lower temperatures during washing machine cycles are encouraged. In this context, disinfectants added to detergents have become an essential factor in compensating for these new habits and preventing the transmission of bacteria, fungi and viruses in the home, as well as controlling the level of odorous microorganisms on clothes. , writes the University of Barcelona in a press release.

These products should be assessed using standardized methods, but current EU regulations only apply to clinical settings and are limited to the main wash cycle. Experts from the Biost3 research group, led by Antoni Monleón, lecturer in the Department of Genetics, Microbiology and Statistics at UB, have statistically validated a new method for evaluating the antimicrobial effectiveness of detergents and textile additives in home environments. The results reveal the validity of the new protocol, which was presented to the European Committee for Standardization (CEN) requesting that it become the European standard.

“It is very difficult to ensure that a product works and that it is a good disinfectant. We work with microorganisms and the results of the evaluation of the effectiveness can be very variable according to the method, the washing machine, the temperature, etc. This is why it is very important to publish a standardized protocol at European level so that manufacturers of disinfectants for household textiles can demonstrate the effectiveness of their products with a methodology much closer to the real situation at home”, says Antoni Monleón, a member of the Biostatistics and Bioinformatics Research Group (GRBIO) integrated into the Barcelona Bioinformatics Association (BIB).

International ring test to simulate household washing conditions

In response to the gap in EU standards, the consortium organized an international ring trial to assess the robustness of a new method specifically designed to test the effectiveness of detergents against microorganisms in a domestic environment. The seven participating laboratories were equipped with five laboratory-scale devices simulating household washing machines, in which seven parameters – including the removal of Escherichia coli Where Staphylococcus aureus tissue-adhering microorganisms – were evaluated at different levels of active substance and at different temperatures.

“Assessing the effectiveness of disinfectants in clothing is a complex process that involves many variables and the method must allow aspects such as temperature, contact time or mechanical and chemical effect to be controlled separately, in order to that the reproducibility is more consistent”, notes Antoni Monléon.

Robust and reproducible method

This assessment methodology not only simulates home laundry processes, but should be applicable as standard procedure across the industry and, therefore, should be a robust and repeatable method. “Robustness – says Antoni Monleón – refers to a statistical concept as a measure of the ability of the method not to be affected by small but deliberate variations in the experiment, such as the use of different washing machines or different temperatures”.

“On the other hand – continues the researcher – repeatability means that if you use the same method with the same procedure in another laboratory, you should obtain a similar result”.

The research results showed that the method was robust to small variations in the experiment, so the repeatability of the experiment and the new method was satisfactory.

In addition, they created a new library — a program that allows very fast calculations — in R language called Diagnobatch, usable in an industrial environment.

More realistic and more economical tests

The new method also replicates home washing conditions more realistically compared to the current protocol, where antimicrobials are tested in industrial washing machines with markedly different characteristics. “In addition – says Monleón – previous studies indicate that a laboratory scale device is not significantly different from a domestic washing machine, but has an important advantage in terms of reproducibility and repeatability.

This new methodology also improves capacity and cost compared to the current protocol, in which antimicrobial efficacy must be tested separately and only one microorganism per washing machine test must be evaluated. “The new protocol allows up to 20 tests to be performed simultaneously (depending on the laboratory-scale device) and all microorganisms are tested in the same test”, explains the researcher.

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