Subcritical water extraction of tiger nut by-products: Assessment of nutritional value and safety

This work tackles a chemical valorization of tiger nut by-products using subcritical water treatment (SWE, Subcritical Water Extraction). The process intensification mechanisms generated in this system enable the recovery of targeted compounds in a cleaner and more efficient manner through enhanced mass transfer. In particular, the combination of high pressures (100 bar) and temperatures (100-200 ºC) enables a more direct extraction, saving time and avoiding the use of organic solvents. After an exhaustive chemical characterization of the matrix, the recovered extracts by SWE were structurally characterized. Particularly, the presence of mono- and disaccharides was detected by Nuclear Magnetic Resonance (NMR), which points out the potential prebiotic activity of tiger nuts extracts towards novel, healthier food products. In turn, a nutritional and safety evaluation of these SWE crude extracts was carried out. Firstly, the mineral and heavy metals profile was evaluated through ICP-MS. In parallel , the antioxidant activity was determined by means of TEAC and DPPH assays. Cell viability assessed by MTT assay in CaCo-2 cell lines was maintained around 100% until 500 mg/mL concentration. Overall, the results reveal that tiger nut by-products represent a suitable alternative for their subsequent application in the development of healthier and safer foods. In addition, it should be highlighted the value of extraction methodologies aligned with Green Chemistry principles and Sustainable Developments Goals (SDGs).