Thermogenic formation of biogenic amines during commercial coffee roasting processes

Abstract

This work shows the influences of free amino acids on the formation of related biogenic amines by thermal decarboxylation in an entire commercial roasting process. Two different C. arabica bean samples were investigated, which differed in terms of origin, variety, altitude and post-harvest process. The formation and degradation pattern of investigated amino acids and biogenic amines was comparable in both different bean samples. For the first time, the intermediate and thermogenic driven formation of histamine and agmatine were shown in the roasting process. Agmatine was formed in two different intensities. Histidine degradation and histamine formation showed molar conversion rates of 90% (Brazilian sample, semi-washed) and 95.6% (Kenyan sample, wet processed), whereas arginine was decarboxylated to agmatine in two steps, with rates of I: 23.5% and 29.8%, and II: 47.3% and 46.6%, respectively. No significant formation of putrescine, ethylamine, ethanolamine, tyramine, tryptamine, cadaverine, phenylethylamine, octopamine and ornithine could be found. The comparison to lab-scale roasting trials in the past offered varying results in regard to the changes of spermidine and histamine in the commercial batches of this study.