For this analysis, the Delvotest® kit for detection of residue of
antibiotics was used. A total of 0.1 mL from each milk sample was
added to the kit ampoules containing B. stearothermophilus. These
ampoules were then incubated in a water bath at 64ºC ± 0.5ºC for 3
hours. After the incubation period, the samples showing a purple color
were considered positive while those with a yellow hue were considered
negative