Separation of Maillard reaction products from xylose—glycine and glucose—glycine model systems by capillary electrophoresis and comparison to reverse phase HPLC

Capillary electrophoresis (CE) and reverse phase HPLC were used to analyse Maillard reaction products (MRPs) formed in refluxed, aqueous xylose—glycine and glucose—glycine model systems. CE was shown to resolve many more components than reverse phase HPLC. Ultrafiltration was used to separate the MRPs into three molecular weight fractions, nominally > 3000, between 3000 and 1000, and < 1000 daltons. Components of the lowest molecular weight fraction migrated as sharp, well-resolved peaks by CE, whereas the components of the higher molecular weight fractions (melanoidin) migrated as a single broad peak in each case. The melanoidin and the majority of the low molecular weight compounds migrate as anions in borate buffer at pH 9.3, some of this anionic character being due to complexation with borate. The majority of colour in the systems was attributed to the melanoidin, with only two other CE peaks in the xylose-glycine, and one in the glucose—glycine systems having significant absorbancies in the visible region.