Analysis of galactosylisomaltol in milk systems using HPLC

While performing the HPLC separation of hydroxymethyfurfural (HMF) from in-bottle sterilised milk samples, two unknown compounds, named by us as X and Y, were observed. Preliminary data indicated that the amount of compound X in the samples was dependent on the intensity of the heat treatment applied to milk. Compound X was isolated from heated solutions of lactose/caseinate and milk, and purified by semi-preparative rp-HPLC. Applying HPLC-DAD, UV, IR, GC–MS and NMR analysis it was possible to identify it as galactosylisomaltol. The analysis of HMF and galactosylisomaltol enables to follow simultaneously, the Amadori product degradation through 1,2- or 2,3-enolisation in milk systems. Higher levels of galactosylisomaltol were found in in-bottle sterilised samples as compared with UHT-treated and pasteurised milks. Galactosylisomaltol was not found either in raw or pasteurised milk.