'In vitro' study about the effect of several penicillins during the fermentation of yogurt made from ewe's milk

摘要

Ewe milk spiked with three beta-lactams (penicillin G, amoxicillin and ampicillin) at three concentrations (0.5, 1 and 1.5 times the MRL) were used to study the evolution of pH during the incubation of yogurts made from ewe's milk. Antibiotic activitywas controlled by the Delvotest SP~R, which detected all antibiotics at the MRL or superior concentration, but only penicillin G under the MRL. The pasteurization treatment (80 deg C, 1 min) reduced the detection for all antibiotics. Ampicillin showed delays in the pH decrease (until 40 min more) at all assayed concentrations and penicillin G when the MRL concentration was exceeded. No delays were stated when amoxicillin occurred in yogurt at any concentration.