Spent Coffee Grounds and Coffee Silverskin as Potential Materials for Packaging: A Review

Coffee is a widely enjoyed beverage and one of the world's most traded commodities. However, it also generates large amounts of bio-based waste including coffee silverskin (CS) and spent coffee grounds (SCG). Both SCG and CS contain oils, polyphenols, and caffeine among other substances, showing potential for valorization. However, most of the SCG and CS generated by the coffee industry is discarded as waste. SCG and CS are lignocellulosic materials that show potential for the production of biocomposites. Because of their hydrophilic character, chemical modification of these wastes is often necessary before compounding with polymers. Oil extracted from SCG can be cultured with bacteria for producing biopolymers. The use of SCG and CS in nanoform has been seldom explored, although CS in particular shows potential as a source of nanocellulose. Utilization of SCG and CS in packaging development could thus be beneficial in the context of the circular economy. Therefore, this review summarizes recent research on the development of packaging materials using SCG and CS. The composition and characteristics of both wastes are presented, and the production of biopolymers and composites using these materials is discussed.

Automated summary

Coffee waste, including spent coffee grounds and coffee silverskin, contains valuable substances like oils, polyphenols, and caffeine, but is mostly discarded by the industry. These wastes show potential for producing biocomposites, but chemical modification is often necessary. Extracted oils from spent coffee grounds can be cultured with bacteria for producing biopolymers.