Impact of Holder Pasteurization on Essential Elements from Human Donor Milk: Total Contents and Protein-Binding Profiles

Holder pasteurization is a thermal treatment commonly applied to milk in human milk banks. However, the application of heating processes can affect the actual composition of milk. In this work, the effect of Holder pasteurization on essential elements in donor human breast milk was studied, including total contents and protein-binding profile of Cu, Fe, Se and Zn. The total contents were determined by inductively coupled plasma mass spectrometry (ICP-MS) and chemical speciation studies were conducted by size exclusion chromatography (SEC) coupled to an ICP-MS and to an UV-vis detector. Total concentrations (mu g/L) of Cu (0.19 +/- 0.01), Fe (0.35 +/- 0.01), Se (0.010 +/- 0.003) and Zn (0.57 +/- 0.01) were obtained before pasteurization and concentrations of Cu (0.19 +/- 0.01), Fe (0.36 +/- 0.02), Se (0.008 +/- 0.002) and Zn (0.57 +/- 0.01) were obtained after pasteurization. Their protein-binding profiles did not change significantly for the majority of the species, indicating a low degree of interconversion due to the elevation of the temperature. However, protein profiles changed after pasteurization, indicating that the losses occurred mainly in the apo form (metal-free form) of proteins rather than in their holo forms (metallo-species).