Abstract
The browning reaction in soy sauce was compared with that in the model system containing sugars (glucose 4%, xylose l%) and amino acids (glycine 5%, glutamic acid 5%). In both cases, browning was developed on heating or static oxidation (spontaneous oxidation). On shaking oxidation (obliged oxidation), on the contrary, browning was observed only in soy sauce, and in the model system it was rather repressed by this treatment. The brown pigments in the model system were fractionated into two components, designated as F-A and F-B, by gel filtration with Sephadex G-25. The amount of F-A was increased on oxidation, and that of F-B was increased on heating but decreased on oxidation. The color of F-A was dark tone and that of F-B was light tone. F-A and F-B were suggested to be analogous to brown pigment P-I and P-III in soy sauce, respectively, judging from the results of gel filtration, characteristics of the color and UV absorption spectra.
Amino acid solutions (hydrolyzates of soybean) resembled soy sauce more closely than the model system in the browning behaviors on shaking oxidation and in chromatographic patterns of brown pigments on Sephadex G-25.
In addition, not only glycine and glutamic acid but also many kinds of amino acids were found to be lost considerably during the browning of soy sauce.
