browning reaction of fructose heated in the presence or absence of lysine were
studied by measuring the absorbance at 420 nm. The time course of the development of the brown color at increasing pH values is shown in Figure 4. The similarity between most of these curves and the UV-absorbance curves suggests that a large proportion of the intermediate products are precursors of brown polymers. No decrease in the absorbance at 420 nm of the fructose solution
was observed at pH 10.0 and at pH 12.0, in sharp contrast with the UVabsorbance
and the maximum brown color value, which was reached at the beginning of the heating period, remained unchanged thereafter. The promoting effect of pH on browning evelopment was in agreement with the literature data