Impact of gas ultrafine bubbles on the efficacy of antimicrobials for eliminating fresh and aged <i>Listeria monocytogenes</i> biofilms on dairy processing surfaces

Ultrafine bubbles (UFB) are a novel concept that has the potential to enhance potency of antimicrobials eliminate biofilms. This study investigated impact incorporating gas (air, CO2, and N2) UFB on chlorine (Cl2; 50, 100, 200 ppm) peracetic acid (PAA; 20, 40, 80 antimicrobial (AM) solutions against fresh (3 days) aged (30 Listeria monocytogenes biofilms polypropylene, silicone, stainless steel surfaces. were statically grown coupons (7.62 × 2.54 cm) at 25°C for 3 or 30 days, by immersing in three-strain cocktail L. brain heart infusion (BHI) broth. The treated submerging AM with without 1 min, then swabbed into Dey-Engley neutralizing broth enumerated BHI agar. Incorporation air, N2 resulted significantly increased log reductions (0.4–1.5 logs) polypropylene surfaces, whereas incorporation CO2 ~1 greater silicone surfaces compared UFB. also demonstrated ppm Cl2 was most effective 50 Cl2, 20 PAA, 40 PAA.