Monitoring aroma changes during human milk storage at -19 °C by quantification experiments

In previous human-sensory and gas chromatographic-olfactometric studies we observed major changes in the overall aroma profile of human milk during frozen storage at -19 °C. The data indicated that the changes were predominantly due to lipid degradation processes, most specifically oxidative decomposition of (poly) unsaturated fatty acids. In the present study, characteristic odorants from degradation and oxidation of fat were quantified by means of stable isotope dilution assays in samples stored at -19 °C for 2 and 6 months, and were compared with fresh human milk control samples. In total 20 odorants were determined, amongst which several highly potent odor substances showed drastic increases in concentration after storage for 6 months, some even by two orders of magnitude. However, even after storage for 2 months several major changes in the aroma profiles of human milk were observed. Our investigations support our previous assumption that storage recommendations for breast milk require reconsideration.