engleski

Transformation of spent coffee grounds to high-value added products

Development of innovative transformation techniques of waste generated by agri-food industry into high-value added products, is one of pillars of circular economy oriented toward “zero- waste” approach. In this respect, we have examined the possibility of complete utilization of spent coffee grounds using sequential extraction by several solvents, followed by alkaline liquefaction of solid residue. Soxhlet extraction of spent coffee grounds with n-hexane has been used for the production of coffee oil, while continuous sequential subcritical extraction of defatted residue by 96% and 50% ethanol, and water for the production of targeted bioactive compounds. The solid residue remained after sequential subcritical extraction was subjected to alkaline liquefaction in order to produce possible carrier for enzyme immobilization. The complete utilization of 100 g of spent coffee ground containing 95 % of dry matter resulted with the production of 10.5 g of coffee oil rich in linoleic and palmitic acid, 330 mg of caffeine and 120 mg of chlorogenic acid, and with 20 g of chemically inert cellulose carrier for the enzyme immobilization. Based on the current evidence, it can be safely concluded that spent coffee grounds represent the valuable raw-material for the production of high value-added products, instead being discarded on landfills.

spent coffee grounds ; transformation ; coffee oil ; caffeine ; enzyme immobilization carriers

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