Monitoring aroma changes during human milk storage at +4 °C by sensory and quantification experiments.

BACKGROUND & AIMS: The effect of human milk storage in the refrigerator has been investigated with regard to sensory changes and modifications to the molecular composition of the milk odour-active volatiles. METHODS: In the present study, characteristic odorants from fat oxidation, known from previous studies, as well as free fatty acids were quantified as representative marker substances by means of stable isotope dilution assays of fresh milk samples and milk samples stored at +4 °C for one and three days, respectively. RESULTS: Sensory evaluation showed that rancid and sweaty odour attributes were generated during storage, resulting in an unpleasant aroma profile for adults; however, odour changes were not as pronounced as those observed in our previous study for freeze storage. Fatty and buttery odour notes and a cooked milk-like smell were also generated. In total eight odorants from fat oxidation were determined and some potent odorants showed slight concentration increases. Moreover, five free fatty acids were determined and these all showed drastic concentration increases, even after storage for just one day. CONCLUSIONS: These investigations support our previous findings that storage recommendations for breast milk might need to be slightly reconsidered in view of potential sensory changes; on the other hand, no negative physiological effects are to be expected from these changes.

Development and validation of an HPLC method to quantify 3,4-dideoxyglucosone-3-ene in peritoneal dialysis fluids.

A method was developed and validated to quantify 3,4-dideoxyglucosone-3-ene in peritoneal dialysis fluids by high-performance liquid chromatography with UV detection after derivatization with o-phenylenediamine. The advantages of this method compared with direct HPLC analysis are (i) the possibility of quantifying 3,4-dideoxyglucosone-3-ene simultaneously together with other glucose degradation products, (ii) the compatibility of the method with MS detection for unequivocal identification of the analyte and (iii) a bathochromic shift of the UV absorbance maximum which leads to higher selectivity. The validated method was used to measure 3,4-dideoxyglucosone-3-ene concentrations additionally to the glucose degradation products 3-deoxyglucosone, methylglyoxal, glyoxal, 5-hydroxymethylfurfural, 2-furaldehyde, formaldehyde and acetaldehyde in 19 commercial products for peritoneal dialysis.