Hot-brewed coffee is the most popular hot beverage in the world, and its health properties have been published in the literature (1). Conversely, over the past decade, cold-brewed coffee has gained popularity, but its eventual nutritional properties are unclear (2). Both hot and cold brewed coffee produce over 6 million tons of spent coffee grounds (SCG) yearly disposed in landfills (3). Moreover, due to water content in SCG approximately 2 kilograms of SCG is produced for every kilogram of coffee beans used for coffee beverage (4). Studies have documented the anti-inflammatory effects of SCG in different intestinal cell lines (5) and antidiabetic effects when tested on different digestive enzymes (6). In metabolic parameters by changes in the gut microbiome in obese and diabetic rats (7, 8) and reduced energy consumption in overweight humans (9). However, studies investigating the nutritional properties of SCG are lacking in the literature. Furthermore, the composition of SCG remains unclear which implicates in the comprehension of the possible mechanisms of action behind the positive outcomes existing studies presented. Hence, the aims of this study were to characterize and quantify bioactive compounds found in SCG using pharmaceutical grade analogues. Therefore, providing a clearer pathway to investigate the potential use of SCG as an environmentally friendly functional food.

Experimental aims This study aimed to characterise bioactive compounds in SCG from two brewing methods, hot and cold brew, and then compare the bioactive compounds founds in SCG with cold- and hot-brewed coffee (beverage) and SCG extracts. Additionally, this study aimed to investigate the effects of SCG extracts in the E.A.hy926 cell line. The purpose of these experiments was to assess if SCG extracts inflict cell damage, influence cell viability, cytotoxicity prior in vitro studies. Finally, this study aimed to test SCG's antioxidant capacity compared to food sources of antioxidant, and antioxidant activity. [...]