Thermal stability of human milk lactoferrin was studied by differential scanning calorimetry and compared with that of recombinant human lactoferrin produced in Aspergillus awamori. Maximum peak temperature, transition enthalpy, and activation energy of lactoferrin as isolated from human milk (67.0 °C, 2276 kJ/mol, and 275.5 kJ/mol, respectively) increased significantly when lactoferrin was fully saturated with iron (90.6 °C, 3209 kJ/mol, and 387.6 kJ/mol, respectively) which indicates that the binding of iron to lactoferrin is an important factor in the stabilization of its structure. Similar results were obtained for recombinant human lactoferrin, indicating a high degree of resemblance between both proteins. The ability of human lactoferrin to bind iron after heat treatment was also studied, remaining practically intact after treatments of 72 °C for 20 s or 135 °C for 8 s, while more severe treatments reduced markedly this ability. Keywords: Human lactoferrin; thermal denaturation; iron-binding ability

A dessert matrix previously used for diagnosis of food allergies was incurred with pasteurised egg white or skimmed milk powder at 3, 6, 15 and 30 mg allergen protein per kg of dessert matrix and evaluated as a quality control material for allergen analysis in a multi-laboratory trial. Analysis was performed by immunoassay using five kits each for egg and milk (based on casein) and six 'other' milk kits (five based on β-lactoglobulin and one total milk). All kits detected allergen protein at the 3 mg kg(-1) level. Based on ISO criteria only one egg kit accurately determined egg protein at 3 mg kg(-1) (p=0.62) and one milk (casein) kit accurately determined milk at 6 (p=0.54) and 15 mg kg(-1) (p=0.83), against the target value. The milk "other" kits performed least well of all the kits assessed, giving the least precise analyses. The incurred dessert material had the characteristics required for a quality control material for allergen analysis.

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The introduction of antimicrobial residues in the food chain has a significant impact on human health. An innovative solution to avoid their presence in meat is the adaptation of current control methods for use with in vivo matrixes. Thus, the aim was to obtain paired blood and muscle samples from pigs treated with some of the main antimicrobials currently used in veterinary medicine (oxytetracycline, sulfamethoxypyridazine, enrofloxacin, amoxicillin), and to compare their rate of depletion in both matrixes. Antimicrobial concentrations in paired samples of blood and muscle were determined by liquid chromatography with tandem mass spectrometry (LC–MS/MS) or high performance liquid chromatography with fluorescence detection (HPLC-FLD). A comparison between values obtained in muscle and blood showed a similar distribution in both matrixes for oxytetracycline; for sulfamethoxypyridazine, a similar decrease rate but a concentration three times higher in blood compared to muscle was found; for enrofloxacin, we found significant differences in the rate of depletion, with similar antimicrobial concentrations in both matrixes with values close to the maximum residue limit (MRL) and higher amounts in muscle for values that lay considerably over the MRL. Conversely, amoxicillin depletion was so rapid that its appearance in carcasses does not seem to pose a risk. Therefore, blood would be a feasible matrix for the development of new in vivo tests.

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