Valorization of Spent Coffee Grounds as Precursors for Biopolymers and Composite Production

Abstract

Spent coffee grounds (SCG) are a current subject in many works since coffee is the second most consumed beverage worldwide; however, coffee generates a high amount of waste (SCG) and can cause environmental problems if not discarded properly. Therefore, several studies on SCG valorization have been published, highlighting its waste as a valuable resource for different applications, such as biofuel, energy, biopolymer precursors, and composite production. This review provides an overview of the works using SCG as biopolymer precursors and for polymer composite production. SCG are rich in carbohydrates, lipids, proteins, and minerals. In particular, carbohydrates (polysaccharides) can be extracted and fermented to synthesize lactic acid, succinic acid, or polyhydroxyalkanoate (PHA). On the other hand, it is possible to extract the coffee oil and to synthesize PHA from lipids. Moreover, SCG have been successfully used as a filler for composite production using different polymer matrices. The results show the reasonable mechanical, thermal, and rheological properties of SCG to support their applications, from food packaging to the automotive industry.

Study on Physicochemical Properties of Biocomposite Films with Spent Coffee Grounds as a Filler and Their Influence on Physiological State of Growing Plants

“…Besides the application in agriculture [20], spent coffee grounds can be a source of energy, as well as used for oil, biodiesel and bioethanol production or be applied as adsorptive filters [16]. Moreover, they can be used as precursors for biopolymer production [21]. Coffee grounds have been added also as a filler into polymeric matrix both to bio-based and oil-based materials [21,22].…”

Zeleni biokompoziti na bazi otpada taloga kave

“…5,6 S obzirom na to da je globalna potrošnja kave prema statistikama Međunarodne organizacije za kavu u razdoblju od 2019. do 2020. godine dostigla vrijednost čak 10 milijardi kilograma, upravo je otpad taloga kave postao predmet od interesa kao jedno od potencijalnih punila. 7,8 Naime, kava koja se upotrebljava za kuhanje i konzumiranje kao pića, iskoristiva je tek u nekoliko posto, što znači da industrije snose veliku odgovornost prema nekontroliranom odlaganju nastalog otpada kave. S druge strane, otpad taloga kave izvor je različitih resursa, poput lipida, proteina i ugljikohidrata te se može prevesti u neki drugi oblik pogodan za uporabu.…”

Organic waste valorisation towards circular and sustainable biocomposites

“…It has been shown that carbohydrates ( polysaccharides) can be extracted and fermented to produce lactic acid, succinic acid, or polyhydroxyalkanoate (PHA) and, in parallel, it is possible to successfully use it as a filler for composite production using the same matrix (or different biobased polymers). 129 Biopolymeric composite performance is also undoubtedly correlated to compositions and phase morphologies, which need to be optimized by using compatibilisation methods or a nanocomposite approach. 130 Naturally derived materials with hierarchical organization are also attractive candidates for high-performance and functional bionanocomposites because of their renewability, biocompatibility, biodegradability, flexibility, and availability of multiple reactive sites for introducing novel functionalities.…”