Study of effect of sterilization on level of Oxytetracycline antibioticresidue in raw milk by ELISA method

Antibacterial drugs are largely used in animals for three objectives including therapeutic application to treat disease in animals, prophylactic utilization to prevent infection in animals, and growth promoters to improve feedutilization and production. Antibacterial drugs used in animal might result in deposition of residues in meat,milk and eggs. The presence of antimicrobial residues in animal-originated food is critical problem in manycountries over the years. Cooking procedure was one of the most important agents that influenced TC residues.Among various procedures studied, microwaving was the most effective one. It is obvious that the more cookingtime, the greater loss of residue. During heat processing, it was identified the most stable and the most unstableTCs are doxycycline and oxytetracycline, respectively. The study was performed by ELISA method; raw milksamples after sterilization were studied again for antibiotic residues. Results showed a significant differencebetween antibiotic concentrations before and after sterilization (p<0.05). Among 22 samples of raw milk(59.09%), 13 positive samples with residue antibiotic and 9 samples without residue antibiotic were reported.Samples were then reduced to 9 positive (40.09%) and 13 negative (59.09%) samples after the sterilization. Thenumber of positive samples in the standard limit of 2.5 ng./ml and above reached to zero after the sterilization.This shows the importance of heating when consuming milk