Impedimetric Estimation of Coliforms in Dairy Products

Abstract
An impedance method was developed for the estimation of coliforms in raw and pasteurized milk, heavy cream, and ice cream mix. Impedance detection times (IDTs) in CM, a medium developed for the impedimetric detection of coliforms, were compared to confirmed Violet Red Bile Agar (CVRBA) plate counts. Correlations of 0.91–0.95 between the two methods were obtained for the four dairy products. The line equations of these relationships were similar for all products. An IDT shorter than 9 hr was indicative of coli‐ form levels >10/mL, while an IDT longer than 12 hr was indicative of levels <10/mL. The impedhnetric estimation of coliforms provided the same information as CVRBA counts from dairy products, offering a savings in time and labor.

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