Minimum time and detection limit required to detect Escherchia coli O157:H7 in fresh-cut cabbage examined by real-time polymerase chain reaction (PCR). The detection limit of E. coli O157:H7 in modified E. coli (mEC) broth by real-time PCR was 1.53 log CFU $mL^{-1}$. A growth curve was produced by counting the cell number of E. coli O157:H7 in mEC broth during cultivation at $37^{circ}C$. The growth curve was well fitted by the equation, $y=0.0148x^2+0.4244x+1.0472$ ($R^2=0.9945$), where y is the cell growth concentration (log CFU $mL^{-1}$) and x is time (h). Assuming that E. coli O157:H7 is present in produce at low concentrations (1 cell in 25 g sample), detection by real-time PCR would be possible only when the cell number increased over the detection limit. The growth curve indicated that culture in mEC broth required at least 6 h and 20 min of enrichment to exceed the detection limit; therefore, the total time required for detection time was less than nine hours, which included the DNA isolation time (30 min) and the real-time PCR operating time (2 h). This method could be used for presumptive screening of E. coli O157:H7 in fresh-cut produce, which demands a rapid detection time for safety management.