ReviewReview on utilization and composition of coffee silverskin

- Coffee silverskin (CS) is the only by-product produced during roasting of coffee beans.
- CS includes dietary fiber (50-60%) protein (16-19%), fat (1.56-3.28%), and ash (7%).
- Subcritical-water is effective for the extraction of active ingredients from CS.
- Solid-state fermentation is effective for producing useful ingredients from CS.

Coffee is one of the most frequently consumed drinks in the world. Coffee silverskin (CS) is the only by-product produced during the coffee beans roasting process, and large amounts of CS are produced by roasters in coffee-consuming countries. However, methods for the effective utilization of CS have not been developed. Reuse of CS, which is the primary residue from the coffee industry, is important for the environment and economy. Recently, there have been some attempts to reuse CS for biological materials and as a nutrient source for solid-state fermentation. The purpose of this review is to provide an overview about CS, its chemical composition, biological activity, and attempts at its reuse.