“Multidimensional correlation analysis of temperature and contact time on eradication of biofilms of Cronobacter sakazakii on abiotic surfaces by combination of hypochlorite and malic acid”

AIM: In the present study, malic acid in combination with sodium hypochlorite is evaluated for the eradication of biofilms formed by Cronobacter sakazakii strains individually and in a cocktail on different abiotic surfaces. METHODS AND RESULTS: The biofilm formation by five strains of C. sakazakii and their cocktail culture on different substrates was studied in Tryptone Soy Broth (TSB) and reconstituted Powdered Infant Formula (PIF). Further, the effect of temperature (4, 27, 37, and 50°C) and contact time (10, 20, 30, 40, 50, and 60 min) on the antibiofilm potential of the test solution (0.0625 mol l-1 malic acid and 0.00004 mol l-1 sodium hypochlorite) against the biofilm formed by C. sakazakii cocktail culture was investigated on these surfaces. The effect was evaluated in terms of viable cell count and biofilm texture using scanning electron microscopy (SEM). Principal Component Analysis (PCA) revealed that the maximum biofilm reduction was observed for stainless steel at 4°C after 60 min of contact, whereas at 25, 37, and 50°C, maximum biofilm reduction was observed for polycarbonate. For glass and polyurethane, maximum log reductions were observed at 50°C. The SEM images revealed cell surface deformation and disruption in biofilms after treatment with the test solution. CONCLUSIONS: The antibiofilm potential was observed to be greatly affected by contact time and temperature. These results indicated that the combination of malic acid and NaOCl can effectively kill and remove C. sakazakii biofilms from food contact surfaces and enteral feeding tubes.