A rapid bioassay for penicillin residues in milk

Abstract

SummaryA new bioassay for the detection of penicillin in milk which can be completed in 1½ h has been developed. The test depends on measurement of pH changes in milk produced by an antibiotic sensitive organism,Streptococcus thermophilusBC. To measure the changes potentiometrically would require a very sensitive pH meter. Change in the enzymic coagulation time, which is extremely dependent on pH, was used in the present study to measure small changes in pH. The test is highly reliable and should be suitable as a milk selection test.