Analyses of the Chemical Structures of Melanoidins by ^<13>C NMR, ^<13>C and ^<15>N CP-MAS NMR Spectrometry(Food & Nutrition)

概要

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Nondialyzable melanoidins, which were prepared from a glucose-glycine system at 95℃ for 7, 26 and 44 hr, were subjected to NMR analyses before and after ozonolysis. On ^<13> CP-MAS NMR, signals in the regions of 10〜50, 60〜75, 105〜115(I), 130〜140(II), 170〜180 and 190〜205(III)ppm were observed for the melanoidins. The signals of I, II and III completely disappeared on ozone-treatment. These findings indicate that the melanoidins were composed mainly of saturated and aliphatic carbons. The 13C NMR spectra of glucose(1-^<13>C)-glycine melanoidins showed that C-1 carbons originating from glucose in the melanoidins were distributed at the positions of aliphatic alkyl methyl(IV), saturated, unsaturated or aromatic and carbonyl(V) carbons. The signals of IV and V disappeared on ozone-treatment. Studies using glycine-2-^<13> revealed that most of the glycine is incorporated into the melanoidins. On ^<15>N CP-MAS NMR, weak broad signals in the region of 0 〜70ppm and strong signals in the region of 70 〜120ppm with a shoulder at 120 〜170ppm(VI) were observed for the melanoidins. The signals of VI disappeared on ozone-treatment. The main linkage of nitrogen(70〜120ppm) was remarkably shifted from that of the original glycine and was determined to be a conjugated enamine linkage.
社団法人日本農芸化学会の論文
1986-08-23