DETECTION OF ESCHERICHIA COLI O157 IN RAW BEEF USING A CCD BASED LIGHT SCATTERING INSTRUMENT

A sensitive and easy-to-perform instrumentational method for the detection of Escherichia coli O157 in raw minced beef is described. The detection is based on a light scattering immunoassay and a charge-coupled device (CCD) direct readout spectrometer measuring the scattered light spectral signals at an optimized angle of 20° to the axis of transmitted light. Using latex particles coated with antibodies for E. coli O157, the method sensitivity has significantly improved comparing with the visual immunoassay assessment method when detecting the presence of this bacterium in spiked beef samples. The method is capable of detecting E. coli O157 at the level of 10³ cfu mL^-1 after 6 h of incubation of the spiked samples. This study has demonstrated a faster technique (within 8 h) for the detection of E. coli O157 in raw beef and a possible new application for the CCD based light scattering instrument.