The coffee bean nitrogenous compounds. A critical review of contemporary scientific literature

Abstract

Two species have gained economic importance in coffee production: Coffea arabica L. (Arabica coffee) & Coffea canephora Pierre ex A. Froehner var. Robusta, with 65 and 35% of world production attributed to C. arabica L. & C. canephora P. respectively. The seeds chemical composition of C. arabica and C. canephora, before roasting, differs with respect to their primary and secondary metabolites content, which serve as precursors for the synthesis of volatile compounds during the roasting process. For this reason, there are marked organoleptic differences between the roasted grain of both species. Unfortunately, although they play an important role during the seed germination, coffee proteins are described as nutritionally deficient due to their lack of essential amino acids. Additionally, most coffee amino acids, polypeptides and proteins are difficult to access because they are trapped in the insoluble waste (bagasse) recovered during the industrial production of instant coffees. The following discussion is the product of an extensive review of current scientific literature which aims to describe the most salient topics associated with the coffee beans’ nitrogenous compounds (primary metabolites) before and after roasting, differences linked to the involved species, their influence on cup quality, solubility, and extraction, as well as a discussion on the analytical techniques used for their determination.