Effects of Species, Post-Harvest Treatment, and Roasting on Fibre, Volatile Compounds, and Polyphenol Contents in Coffee Silverskin.

Although coffee silverskin (CS) has recently been used as a food ingredient, no knowledge has been reported on the effects of species or different post-harvest treatments on its chemical composition. Therefore, the fibre, volatile compounds, phenolic acid content, and antioxidant capacity of CS samples obtained at three roasting intensities (light, medium, and dark) from the and species, each subjected to a washing or a sun-drying ("natural") post-harvest treatment, were studied. Obtained results showed that the chemical composition of CS is due to species, roasting, post-harvest treatment, and interaction. In particular, natural CS showed the highest content of volatile compounds of Maillard and varietal origin, whereas washed CS showed the highest content of soluble dietary fibre and chlorogenic derivatives. Pyrroles, sulphur compounds, and pyridines contents were higher in CS than in CS. The dark-roasted washed CS showed the highest content of 5-- and 3--caffeoylquinic acids, while the natural CS highlighted the highest antioxidant capacity. The effect of post-harvest treatments seemed to be emphasised in CS, independent of roasting, which did not significantly affect the antioxidant capacity of CS from either species.