Investigations of peptides and proteases in green coffee beans

Cof. canephora

var. robusta. The coffee types were not significantly different in peptide content, but were significantly different in peptide composition. Peptides with weakly acid pI values were mainly found in the Cof. robusta samples. In comparison, peptides from Cof. arabica samples ranged evenly from the weakly acidic up to the weakly basic pH range. The apparent molecular masses of the peptides in the two groups of samples lie between 4 kDa and 10 kDa. The cysteine content of the peptides was relatively high. Model roastings permitted the assumption that peptides make a contribution to coffee flavour. Peptides are already available in freshly harvested coffee. Model tests have suggested that processing after the coffee harvest has an influence on peptide composition but not on the amounts of peptide. All coffee samples contained some extractable proteases. The electrophoretically obtained enzyme patterns of Cof. arabica and Cof. robusta were different.