Enrofloxacin treatment on dairy goats: Presence of antibiotic in milk and impact of residue on technological process and characteristics of mature cheese

Lately quinolones, particularly enrofloxacin, have been incorporated as a veterinary treatment of small ruminants, like goats, whose milk is highly appreciated for the manufacture of traditional cheeses. This study aims to evaluate the influence of the presence of enrofloxacin in milk (from goats previously treated with this antibiotic), on the characteristics (chemical composition; colour, texture, volatile profile and sensory evaluation) of mature cheese at 0, 30 and 60 days. Three batches of cheeses were made from milk obtained at three different times with respect to the animals’ antibiotic administration (24 h before treatment, 24 h after treatment, and after the withdrawal period). The manufacture process of cheese is not affected by enrofloxacin in any way; therefore, it will remain unnoticed in the production line. A transfer of enrofloxacin, and its metabolite ciprofloxacin, to the cheese produced with milk obtained 24 h after treatment was observed. The presence of antibiotic residues does not produce significant changes in any of its compositional, texture and colour characteristics, when compared to the cheeses made before veterinary treatment with antibiotic-free milk, with the only exception of some compounds of the volatile fraction. Enrofloxacin and its metabolite show high stability during the cheese maturation (51% of both remain after 60 days of ripening). In general, the presence of this antibiotic has lesser effects on all the characteristics of the cheese compared to those modifications produced during the maturation time. Sensory measures of odour, colour, appearance and texture attributes, as well as the global preference, are also not affected by this antibiotic, which would imply a risk for the population since its presence would go undetected.