Abstract
Effects of the types of sugars and buffers, and pH on the formation of Maillard reaction pigments were investigated using the xylose-lysine and glucose-lysine model systems. Sugars (13.3 mM) and lysine (34 mM) were dissolved in acetate, phosphate, and tris(hydroxymethyl)aminomethane (Tris) buffers and heated at 100°C for 60 min. The profiles of browning, reversed-phase HPLC, sugar-decrease, and gel permeation chromatography of each sample were examined. Browning was stimulated by phosphate and inhibited by Tris. With the rise in pH value, browning occurred more intensively, more sugars decreased, and more melanoidins were formed. Xylose samples turned darker brown than glucose ones. The ratio of absorbance at 400 nm to that at 450 or 500 nm increased in the xylose system with the rise in pH value, while that in the glucose system decreased. Low-molecular-weight pigments, dilysyldipyrrolones, were formed only in the xylose system, while melanoidins were formed in both systems. Lysine stimulated the degradation of sugars, polymerization, and browning in both systems, although more intensively in the xylose system than in the glucose one.
