Rapid detection of Escherichia coli in milk and cream by impedance measurement
2004
Holubova, J.,Vysoka skola chemicko-technologicka, Praha (Czech Republic). Fakulta potravinarske a biochemicke technologie, Ustav chemie mleka a tuku, Technicka 3, 166 28 Praha 6 | Curda, L.,[email protected] | Chumchalova, J.
This work was focused on the rapid detection of milk and cream recontamination, Escherichia coli being used as a model microorganism. Milk, cream, impedance Medium 001A and Nutrient Broth were the media tested. Impedance of the medium was more suitable for measurement in milk, cream and Medium 001A (shorter detection time, lower standard deviations); only electrode impedance was usable for Nutrient Broth. Glucose added to milk and cream did not affect the growth of E. coli. Detection in Medium 001A was about 20 min faster, when Supplement S for spore-forming bacteria was added. Linear equations between log CFU per ml (plate count method) and detection time were calculated. Residual standard deviations for milk, cream, Medium 001A and Nutrient Broth were sy,x=0.1077, sy,x=0.1016, sy,x=0.2783, and sy,x=0.4144, respectively, and the correlation coefficients were higher than 0.98 in all cases. Cell concentration (CFU per ml) was retrospectively calculated from the detection time and thus the linear equation was confirmed. Duration of E. coli detection in the impedance Medium 001A was comparable to that of the direct determination in milk and cream.
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