Extraction and characterization of functional duckweed proteins using alkaline, enzymatic, and ultrasound-assisted...

The urgent need for sustainable, plant-based protein sources has brought aquatic crops like duckweed (Lemnaceae) into focus due to their high protein content, fast growth, and minimal resource requirements. This study aims to optimize and compare alkaline, enzyme-assisted, and ultrasound-assisted extraction techniques to produce high-yield, functional protein concentrates from Lemna minor. Key extraction parameters-pH, temperature, and solvent-to-solid ratio-were systematically optimized, identifying pH 9, 55 °C, and 5 mL/g as ideal conditions. Ultrasound treatment (100 % amplitude, 10 min) and Alcalase L enzyme application significantly enhanced protein yields. Ultrasound-assisted extraction proved most effective, increasing protein yield by more than fivefold compared to conventional alkaline methods, reaching 60.09 % protein content on a dry basis. The resulting protein concentrates displayed desirable functional properties, including excellent solubility (92.19 % at pH 9), foaming capacity (92.62 %), and emulsion activity, all of which are critical for food applications. Comprehensive structural and compositional analyses confirmed the presence of essential amino acids, high mineral content (notably calcium and phosphorus), and acceptable techno-functional behavior. SEM and FTIR analyses supported the structural integrity of the extracted proteins, while flowability assessments suggested suitability for powder-based formulations. This research demonstrates that ultrasound-assisted protein isolation from duckweed offers a scalable and efficient strategy for producing high-quality protein concentrates. These findings position duckweed as a promising, sustainable protein source with strong potential for incorporation into functional foods and novel plant-based formulations.