A group of researchers from the University of Navarra (Spain) examined the antioxidant content of the coffee waste and they found that a large amount of the antioxidants from coffee remain in the waste product. Thus waste from brewing coffee could be a valuable resource for the production of antioxidants for dietary supplements. The Journal of Agriculture and Food Chemistry reports the novel findings of this study.
The main hydrophilic antioxidant compounds (3-, 4-, and 5-monocaffeoylquinic and 3,4-, 3,5-, and 4,5-dicaffeoylquinic acids, caffeine, and browned compounds, including melanoidins) and the antioxidant capacity (Folin-Ciocalteu, ABTS, DPPH, Fremy’s salt, and TEMPO) were evaluated in Arabica and Robusta spent coffee obtained from the preparation of coffee brews with filter, espresso, plunger, and mocha.
The researchers reported that all spent coffee grounds, with the exception of those from the mocha coffeemaker, had relevant amounts of total caffeoylquinic acids (6.22-13.24 mg/g of spent coffee), mainly dicaffeoylquinic acids (3.31-5.79 mg/g of spent coffee), which were 4-7-fold higher than in their respective coffee brews. Caffeine ranged from 3.59 to 8.09 mg/g of spent coffee. The antioxidant capacities of the aqueous spent coffee extracts were 46.0-102.3% (filter), 59.2-85.6% (espresso), and <42% (plunger) in comparison to their respective coffee brews.
In conclusion, the scientists suggest that coffee waste may be a rich source antioxidant for supplements. bioactive compounds.