Novel food ingredients from Cyperus rotundus L.: an ancient famine food and the world's pernicious weed coming back on the table

The increasing vulnerability of global food systems has led to an interest in the rediscovery of underutilised plant species as alternative and resilient food resources. Among these species, edible weeds such as Cyperus rotundus L., may represent a promising resource. Even though C. rotundus has been considered as one of the most invasive weed species, it produces energy-rich tubers that have been traditionally consumed but remain poorly characterised from a nutritional and technological perspective. This study provides a comprehensive evaluation of the chemical and metabolomic profile, techno-functional properties, digestive behaviour, and phenolic content. Proximate analysis revealed high total dietary fibre content (39.05 ± 1.23 g/100 g FW), dominated by insoluble fibre, followed by starch (15.00 ± 0.53 g/100 g FW), alongside moderate protein levels (8.44 ± 0.14 g/100 g FW). Elemental analysis performed by ICP-MS revealed a mineral profile dominated by nutritionally relevant macronutrients, particularly Ca, K, P, and Mg, and allowed the determination of microelements and trace potentially toxic elements (PTEs), including As, Cd, Pb, and Ni, which were detected only at low concentrations. The untargeted 1H NMR metabolomic analysis identified 37 metabolites, including free sugars, organic acids, fatty acids, sterols, amino acids, and bioactive compounds such as arginine, γ-aminobutyric acid (GABA), and luteolin-7-O-glycoside. Techno-functional analysis showed favourable water- and oil-holding capacities, and stable pasting behaviour, moderate foaming capacity with high foam stability, and suitability for coarse emulsion systems. In vitro digestion demonstrated slow starch hydrolysis, with reducing sugar release closely matching that of the low-digestible starch fraction, suggesting a potential low-glycaemic response. Total phenolic content was 4.71 ± 0.04 mg GAE/g DW. Overall, these findings indicate C. rotundus tubers as a promising candidate for valorisation within modern food and feed systems, where resilient and underutilised species are increasingly essential to face future climate and security challenges.