MRPs from the other basic and nonpolar amino acids such
as arginine, phenylalanine, leucine, isoleucine, and valine
was also high, this being followed by the MRPs from the
acidic amino acids such as aspartic acid and glutamic
acid, while that of MRPs from cysteine had the lowest
value. As the heating time was increased, the color intensity of the MRP from lysine became 2–3 times higher
than that from the other amino acids (Fig. 2).
Figure 3 shows the remaining percentages of unreacted
glucose in nine MRPs during the reaction period. Glucose
was gradually degraded during the course of heating,
being almost completely destroyed in the MRPs from
lysine and arginine after 12 h, however the MRPs from
aspartic acid, glutamic acid, and cysteine respectively
remained 27.25%, 16.21%, and 18% of the original
glucose.
Figure 4 shows the rate of change in the color intensity
of the MRPs in the presence of metal ions. After being