Amino acid profiles in unripe Arabica coffee fruits processed using wet and dry methods

Abstract

The quality of natural coffee produced in Brazil is quite variable. Fruits at different stages of maturation can be found on the same plant, and unripe fruits are naturally present during the harvest. The pulping of ripe fruits can be effectively used to improve the quality of the coffee, as the ripe fruits will be separated from the unripe fruits; however, the presence of a portion of unripe fruit (with lower quality) in the processing is unavoidable. The wet processing of immature coffee fruit appears to be a potential way of improving its quality. According to the coffee processing used post-harvest, changes were observed in the levels of free amino acids in immature coffee beans. Among the amino acids present, asparagine is the primary amino acid found in unripe coffee beans. Asparagine produces acrylamide, a potentially harmful substance generated during the course of the Maillard reaction. In this study, amino acids in immature coffee beans were analysed using reversed-phase chromatography and ultraviolet detection after the derivatisation with phenylisothiocyanate. The amino acid profiles of the immature coffee beans demonstrated that asparagine is present at more significant levels when immature coffee fruits were processed via dry processing, as compared to wet processing.