Elemental and metabolomic characterization of coffee plant by-products for functional beverage development

Coffee is one of the most widely consumed beverages worldwide. Currently, only the beans are commercially exploited in the food industry, making them the sole source of income for coffee growers. This limited use is critical in terms of sustainability, as the entire coffee production chain is associated with a significant environmental footprint, largely due to the intensive use of water, land, fertilizers, pesticides, and fossil energy. The production process also generates substantial amounts of waste: it is estimated that approximately 0.9 kg of waste is produced for every kilogram of harvested coffee cherries. Among the various by-products are residues from plant pruning and the extraction of bean from the berry. In this context, the valorization of coffee by-products within a circular economy framework is essential for reducing environmental impact. Consequently, in the present study, through chemical and metabolomic approaches, freeze-dried leaves and fruit skins derived from two Caturra varieties (Rojo and Amarillo) of Coffea arabica were analyzed, in order to assess their content of essential nutrients (macro- and microelements) and the presence of potential bioactive compounds for the development of functional beverages. More in detail, elemental analysis using inductively coupled plasma atomic emission spectroscopy (ICP-AES) revealed a comparable elemental profile across both tissues and varieties. In parallel, liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) metabolomic analysis on the polar fraction was performed using both targeted and untargeted approaches, with methanolic and aqueous extractions to simulate the overall biochemical profile and the brewing process, respectively. Thus, a better understanding of the elemental profile and presence of phytochemical constituents could provide valuable insights into processing and extraction methods in order to preserve these compounds to better enhance the use of coffee leaves and berries in the formulation of new functional beverages. Acknowledgement: This work has been supported by METROFOOD-IT project which received funding from the European Union - NextGenerationEU, PNRR - Mission 4 “Education and Research” Component 2: from research to business, Investment 3.1: Fund for the realisation of an integrated system of research and innovation infrastructures – CLP IR0000033, CUP I83C22001040006 (D.M. Prot. n.120 del 21/06/2022).