Efficiency of Innovative Extraction Technologies in Recovering Natural Pigments, Polyphenols, and Antioxidants from Sugar Beet Leaves

The growing demand for agri-food by-product valorisation has driven the adoption of innovative extraction techniques. This study evaluates and compares pulsed electric field (PEF), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE) for the recovery of total polyphenols (TPC), chlorophylls, and antioxidant activity (AA) from sugar beet leaves (SBL). The outcomes depended strongly on the applied technology and the properties of the target compounds. PEF treatment at 7.5 kV for 3 min resulted in a TPC of 11.41 mg GAE/g dry matter, while the highest chlorophyll content (0.393 mg/g dry matter) was obtained at 2 kV for 3 min. UAE using 80% methanol provided 8.23 mg GAE/g dry matter TPC after 5 min, whereas the highest chlorophyll content (0.601 mg/g dry matter) was achieved after 3 min. MAE resulted in the highest TPC (23.75 mg GAE/g dry matter) at 60 °C, 5 min, and a 1:40 solid-to-solvent ratio, while the highest AA (44.57 mg AAE/g dry matter) was obtained at 80 °C, 10 min, and the same 1:40 ratio. Overall, these findings demonstrate that target-specific extraction strategies are essential for SBL valorisation. These results represent the best-performing conditions within the investigated experimental ranges and provide an initial basis for further research into the potential of these technologies for SBL valorisation.