Identification of substituted hydroxypyridines and hydroxypyrazines in caramel food colourings

Abstract

Chloroform‐ethanol soluble components from 15 caramel colourings have been separated by gas chromatography, after trimethysilylation. Mass spectra have been obtained on the components shown present. Ten compounds have been structurally identified, namely: 3‐hydroxypyridine, 2‐hydroxymethylpyridine, 3‐hydroxy‐6‐methylpyridine, hydroxymethylpyrazine, 2‐hydroxymethyl‐5‐methyl‐pyrazine, 1’,2'‐dihydroxyethylpyrazine, and the 2,5‐ and 2,6‐isomers of l’,2'‐dihydroxyethylmethylpyrazine, and the 2,5‐ and 2,6‐isomers of methyl‐(l’,2’,3’,4'‐tetrahydroxybutyl) pyrazine.