Heat Inactivation of β-Lactam Antibiotics in Milk

Abstract

The presence of residues of antimicrobial substances in milk is one of the main concerns of the milk industry, as it poses a risk of toxicity to public health, and can seriously influence the technological properties of milk and dairy products. Moreover, the information available on the thermostability characteristics of these residues, particularly regarding the heat treatments used in control laboratories and the dairy industry, is very scarce. The aim of the study was, therefore, to analyze the effect of different heat treatments (40 degrees C for 10 min, 60 degrees C for 30 min, 83 degrees C for 10 min, 120 degrees C for 20 min, and 140 degrees C for 10 s) on milk samples fortified with three concentrations of nine beta-lactam antibiotics (penicillin G: 3, 6, and 12 microg/liter; ampicillin: 4, 8, and 16 microg/liter; amoxicillin: 4, 8, and 16 microg/liter; cloxacillin: 60, 120, and 240 microg/liter; cefoperazone: 55, 110, and 220 microg/liter; cefquinome: 100, 200, and 400 microg/liter; cefuroxime: 65, 130, and 260 microg/liter; cephalexin: 80, 160, and 220 microg/ liter; and cephalonium: 15, 30, and 60 microg/liter). The method used was a bioassay based on the inhibition of Geobacillus stearothermophilus var. calidolactis. The results showed that heating milk samples at 40 degrees C for 10 min hardly produced any heat inactivation at all, while the treatment at 83 degrees C for 10 min caused a 20% loss in penicillin G, 27% in cephalexin, and 35% in cefuroxime. Of the three dairy industry heat treatments studied in this work, low pasteurization (60 degrees C for 30 min) and treatment at 140 degrees C for 10 s only caused a small loss of antimicrobial activity, whereas classic sterilization (120 degrees C for 20 min) showed a high level of heat inactivation of over 65% for penicillins and 90% for cephalosporins.

Degradation of cefquinome in spiked milk as a model for bioremediation of dairy farm waste milk containing cephalosporin residues

“…Heating is recognized as a method for inactivating b-lactam antibiotics in milk and other foodstuffs (Moats 1988;Zorraquino et al 2008). In our study, the effect of heat treatment alone was investigated in spiked UHT milk to control for the effects of fermentation of endogenous bacterial flora that are present in unpasteurized milk.…”

Complexation Between Casein Micelles and Whey Protein by Indirect UHT- Processing of Milk: Influence of Surface Hydrophobicity and Dye-Binding Characteristics of Micelles in Relationship with Their Physico-Functionality

“…3a).It might explain that protein-bound AB's in heated milk samples are underestimated owing to their lacking analytical availability. This event gives rise to a common misinterpretation believing that AB's in milk are degradable on heating (22).…”

Influence of enrofloxacin on the coagulation time and the quality parameters of goat's milk yoghurt

“…However, some of these antimicrobial substances are hardly affected by heat treatments usually carried out by the dairy industry (Zorraquino et al . ; Roca et al . ) or by the manufacturing processes themselves (Grunwald and Petz ; Adetunji ), and therefore, variable amounts of drug residues could remain in the final products, if present in raw milk.…”