Coffee consumption decreases the risk of oxidative stress-related diseases. The byproduct
obtained after brewing process (spent coffee) also has antioxidant capacity. Spent
coffee and coffee brews (filter and espresso) extracts were obtained from Arabica and Robusta
coffees, respectively. Spent coffee showed slightly high amounts in chlorogenic acids, but
caffeine content was similar to their respective coffee brew. All samples exhibited strong
protection activity against indirect actingmutagen 2-AF (≤92%), whereas the protection against
NPD (direct mutagen) was 12–35% (Ames Test). The growth inhibition of common foodborne
pathogen and food spoilage microorganisms by coffee extracts was also studied. Spent
coffee showed antimicrobial activity, mainly against Gram-positive bacteria (Staphylococcus
aureus, Listeria monocytogenes) and yeast (Candida albicans). The role of phenolic acids, caffeine
and melanoidins in the antimutagenic and antimicrobial activities is discussed. Thus,
spent coffee extracts could be a potential source of bioactive compounds, thereby becoming
a promising new functional food ingredient.