Biofilm formation on stainless steel as a function of time and temperature and control through sanitizers

Enterococcus spp. contamination was screened from a Minas Frescal cheese processing line. Biofilm formation of Enterococcus faecium and Enterococcus faecalis isolates was evaluated and the effect of sanitization procedures in the control of these biofilms was investigated. Enterococcus spp. were detected in raw milk, milk machine, door handle, floor, drain, thermometer, and Minas Frescal cheese. Biofilm formation on stainless steel was modelled as a function of time (0, 1.2, 4, 6.8, and 8 days) and temperature (7, 13, 27, 41, and 47 °C) using response surface methodology. The model showed that E. faecium biofilms were formed from 1 to 8 days at 12-47 °C, while E. faecalis biofilms were formed from 1 to 8 days at 10-43 °C. None of the sanitizers (sodium hypochlorite 100 mg L−1, peracetic acid 300 mg L−1, and chlorhexidine digluconate 400 mg L−1) was able to completely eliminate the biofilms.