Use of a Simple Fermentation Test to Detect Antibiotic Residues in Milk ^{1, 2}

Area of Science:

• Microbiology
• Food Science
• Pharmacology

Background:

• Traditional fermented dairy products like Lebanese yogurt (Laban) are vital to local diets.
• Antibiotic residues in milk can affect starter cultures and fermentation processes.
• Monitoring for inhibitory substances is crucial for dairy quality control.

Purpose of the Study:

• To assess the antibiotic sensitivity of a local Lebanese yogurt culture.
• To determine the prevalence of lactic acid bacterial inhibitory substances in Lebanese milk.

Main Methods:

• Testing the sensitivity of fresh and freeze-dried Lebanese yogurt cultures to various antibiotics.
• Evaluating the impact of specific antibiotic concentrations on Laban fermentation.
• Screening 858 milk samples for the presence of inhibitory substances.

Main Results:

• Laban fermentation was significantly inhibited by penicillin, streptomycin, dihydrostreptomycin, chloramphenicol, and oxytetracycline at specific concentrations.
• 11.20% of the analyzed Lebanese milk samples contained lactic acid bacterial inhibitory substances.
• Sensitivity varied between fresh and freeze-dried cultures.

Conclusions:

• Local Lebanese yogurt cultures exhibit sensitivity to several common antibiotics.
• The presence of inhibitory substances in Lebanese milk poses a potential risk to traditional dairy fermentation.
• Further standardization of methods is recommended for accurate detection.