Studies on Browning Reaction Products from Reducing Sugars and Amino Acids

Abstract

The nitrogen contents of the melanoidins purified from the heating mixtures of 2M D-xylose with 2M, 4M or 10M ammonia were 11.62, 12.47 and 12.86% respectively, and each melanoidin showed almost similar antioxidative activity on linoleic acid.On the contrary, the melanoidins purified from the heating mixtures of 2M D-xylose with 2M glycine, 2M ammonia, 2M L-arginine, 2M L-lysine or 2M L-histidine were divided into two groups on the nitrogen contents. One is a D-xylose-glycine and -L-lysine group containing about 6% of nitrogen and the other is a D-xylose-L-arginine, -L-histidine and -ammonia group containing the nitrogen of 11-12%. The latter group of melanoidin showed more inhibitory effect on the oxidation of linoleic acid than the former group, but the antioxidative activities were not always proportional to the nitrogen content in each melanoidin.In the comparison of the antioxidative activity of the melanoidin prepared from D-xyloseglycine with legal antioxidants at the same level of reducing power, the melanoidin exhibited more inhibitory effect on the oxidation of linoleic acid than BHA, propyl gallate or erythorbic acid. On the other hand, the comparison at the same level of weight showed that melanoidin has almost the same antioxidative activity on linoleic acid as BHA and a lower activity than BHT. Furthermore, a synergistic effect was observed in the combination of the melanoidin with BHA.