Sm. Monti et al., LC/MS analysis and antioxidative efficiency of Maillard reaction products from a lactose-lysine model system, J AGR FOOD, 47(4), 1999, pp. 1506-1513
Aqueous solutions of lactose and lysine were refluxed for up to 4 h without
pH control. Samples were collected every hour, and the reaction was monito
red by measuring the pH, the optical density at 420 nm, and the relative an
tioxidative efficiency (RAE). The greatest change in optical density and an
tioxidative efficiency occurred for the mixture heated for 4 h. The 4 h sol
ution was separated into three fractions according to the molecular weights
of the components and tested for RAE. The high molecular weight fraction w
as more colored, and it had the highest antioxidative activity. The low mol
ecular weight fraction was separated by high-performance liquid chromatogra
phy (HPLC). RAE values were measured for each purified compound. HPLC coupl
ed with diode array and electrospray mass spectrometry allowed a rapid scre
ening of the solutions and a tentative identification of several peaks. Nuc
lear magnetic resonance analysis allowed the identification of galactosylis
omaltol and pyrraline. The resonance assignments for these compounds were r
evised.