Investigation of the effect of scallop shell powder on cleaning biofilm forming on stainless steel surfaces

The last decades, Listeria monocytogenes, Stahpylococcus aureus and Escherichia coli O157:H7 biofilms emerged a threat for dairy and meat industries on steel surfaces. In this study, the effect of scallop shell powder (SSP) on removing biofilm of these pathogens from stainless steel plates has been examined.Whey and bench washing water (BWW) provided from dairy and meat factories, respectively, were inoculated by L. monocytogenes, S. aureus and E. coli O157:H7 (9 log10kob/ml). Stainless steel plates (10 cm2) were placed in inoculated fluids and incubated at 20°C at 48 hours to form biofilm. Then, the plates were dried, washed by sterile water, dipped in sterile water, 0.25 and 0.50% SSP slurries for 1, 5 and 10 min and determined the number of cells on the plates. The results showed that 0.25 and 0.50% SSP reduced the number of L. monocytogenes on the plates 4 log10kob/cm2. Application of 0.50% SSP for 1 min also removed S. aureus by 5 log10kob/cm2 from the plates incubated in whey. Furthermore, biofilm of E. coli O157:H7 formed in whey or BWW was cleaned by 6 log10kob/cm2 and 4 log10kob/cm2 using 0.50% SSP for 5 min, respectively. Treatment time didn?t change effect of SSP (p>0.05). Also, increasing concentration of SSP significantly increased its reduction effect against tested pathogens from plates (p<0.05)In conclusion, this study showed that SSP slurries significantly cleaned L. monocytogenes, S. aureus and E. coli O157:H7 biofilms from stainless steel surfaces. So that, SSP could be used as an alternative disinfectant in food industries.