Mathematical Models for the Biofilm Formation of and on Stainless Steel Surface in Whole Milk.

Biofilm formation of , and in milk on stainless steel were monitored at 55°C, 60°C, and 65°C for various incubation times. Although species of showed a rapid response and produced biofilm within 4 h on stainless steel, a delay (lag time) was observed for . A hyperbolic equation and a hyperbolic equation with lag could be used to describe the biofilm formation of and , respectively. The highest biofilm formation amount was obtained at 60°C for both and . However, the biofilm formation rates indicated that the lowest rates of formation were obtained at 60°C for . Moreover, biofilm formation rates of (1.2-1.6 LogCFU/mL·h) were higher than (0.4-0.7 LogCFU/mL·h). Although had the highest formation rate values (2.7-3.6 LogCFU/mL·h), this was attained after the lag period (4 or 5 h). This study revealed that modeling could be used to describe the biofilm formation of thermophilic bacilli in milk.