FOAM BASED ON BIOSURFACTANTS FOR CLEANING PIPES AND OPEN SURFACES CONTAMINATED WITH Bacillus subtilis SPORES

In the food industry, the risk of food contamination from the surfaces of processing equipment is significant. Cleaning these solid surfaces is crucial, but often requires considerable use of water and chemicals. To optimize these cleaning practices and make food industries more sustainable, innovative cleaning processes are needed. Our aim is to study the decontamination effect of foams based on biosurfactants in order to decrease the environmental impact of the cleaning processes (decrease amount of water and chemicals) and to understand the foam properties governing the decontamination. Foams decontamination process in static and dynamic conditions were studied.

In the first step, we studied the use of foam flow (dynamic conditions) based on alkyl polyglucosides (APGs) to clean stainless-steel pipes contaminated with Bacillus subtilis spores. Foams were characterized during flows in terms of foam stability and bubbles size. The efficiency of spores’ removal was assessed by enumerations. We found that APG-based foam flows effectively removed spores from closed surfaces. Through a life cycle assessment, we determined the environmental footprint of the APG-based foam flow process.

Then, we used foams to decontaminate open surfaces under static conditions. We produced foams based on 10-hydroxystearic acid (10-HSA) soap. By coupling microscopy and small angle neutron scattering, we determined that 10-HSA soap in water self-assembled into multilamellar tubes giving rise to stable foams. We studied the effect of foam properties (bubbles size and liquid fraction) on cleaning stainless steel surfaces contaminated with Bacillus subtilis spores. Foams with high liquid fraction and with small bubbles size were the most efficient to remove Bacillus subtilis spores through the imbibition trough the foam.

Our work on foams based on biosurfactants for decontamination highlights the potential of foams to improve cleaning due to two main properties: foam friction for dynamic conditions and foam imbibition for static conditions.