Duckweed (Lemna minor) is a fast growing aquatic plant rich in proteins and other nutritional compounds. Ultrasonic extraction is used as a highly efficient and reliable processing technology to release proteins, lipids and phyto-nutrients from duckweed. Sonication allows for the simple and rapid treatment of duckweed for food-grade products.

Duckweed for Nutritional Purposes

Duckweed (genus Lemna), a flowering aquatic plant, is the smallest flowering plants known. Also known as Wolffia, water lentils, or water lenses, duckweed grows in freshwater environments and can be found worldwide. In the duckweed genera, various species such as Spirodela, Landoltia, Lemna, Wolffiella and Wolffia are known. Since the Lemna plant has a rapid growth capacity able to double in size on a daily basis, duckweed has caught interest from scientists and food engineers working in the field of nutrition, food security, and functional foods. In parts of Southeast Asia, duckweed is known since long times for its nutrient-density and is known under the nickname “vegetable meatball” due to its high protein content (more than 45% of dry mass). Duckweed offers the complete protein profile (such as hen eggs), containing all nine essential and six conditional amino acids.

Lipids and Proteins from Duckweed

Duckweed contains 20–35% protein, 4–7% fat, and 4–10% starch per dry weight. Interestingly, the amino acid distributions in duckweed are close to the WHO recommendations, having e.g., 4.8% lysine, 2.7% methionine and cystein, and 7.7% phenylalanine and tyrosine. The content of polyunsaturated fatty acids was between 48 and 71% and the high content of n3 fatty acids resulted in a favourable n6/n3 ratio of 0.5 or less.” (Appenroth et al. 2017)

Ultrasonic Extraction of Duckweed

Ultrasonic extraction is used to extract duckweed compounds, especially proteins and lipids as food products. Lemna protein meal and Lemna lipids are efficiently released and isolated from the aquatic duckweed plant.

How Is Sonication Applied for Duckweed Extraction?

After harvesting the Lemna, excess water is removed (e.g., by centrifugation). For ultrasonic extraction, a biomass-rich (i.e, Lemna-dense) slurry is preferrable as it makes the ultrasonic process more efficient. The duckweed slurry can be consist of duckweed and water or another solvent of choice. This slurry is them fed into an ultrasonic reactor, where acoustic cavitation breaks the cell matrix up and releases the intracellular compounds into the water- or solvent-based extraction medium.

Choose your Extraction Solvent

Ultrasonic extraction is compatible with (almost) any kind of solvent. In research setting, duckweed compounds have been extracted using solvents such as the polar solvent ethanol as well as various non-polar solvent mixtures including methanol-ethanol, chloroform-ethanol, hexane-ethanol, diethyl ether-ethanol, petroleum ether-ethanol at different volume ratio.
The right solvent in combination with ultrasonication intensifies the phyto-nutrient release of duckweed biomass. Ultrasonication homogenizes and disrupts the plant cell structures resulting in cell disruption and disintegration. Ultrasonic extraction is used widely for the production of botanical, fungi, and algae extracts.

The Mechanism of Ultrasonic Extraction

Power ultrasound coupled into liquids or slurries results in energy-intense effects such as acoustic cavitation, shear and vibration. These effects of power ultrasound are successfully applied to disintegrate and destruct cellular structures. Additionally, sonication breaks molecular bondings of lipids, proteins and carbohydrates so that the targeted macronutrients and phyto-chemicals are released from the cell interior of the botanical raw material, e.g. duckweed. Thereby, ultrasonication intensifies and shortens the extraction considerably.

Ultrasonic Extractors for Duckweed Proteins and Lipids

High-performance ultrasonic extraction systems from Hielscher Ultrasonics are used worldwide on R&D, small, mid-size and fully-commercial production levels. High-performance ultrasonic extractors intensify the extraction process and increase yield and overall-efficiency of high-quality extract production. Hielscher Ultrasonics offers extraction equipment for any volume / process capacity. Having experience in botanical extraction for more than 25 years, Hielscher Ultrasonics is your trusted partner for high-performance ultrasonic extraction!

High-Performance, State-of-the-Art Ultrasonicators

The smart features of Hielscher ultrasonicators are designed to guarantee reliable operation, reproducible outcomes and user-friendliness. Operational settings can be easily accessed and dialled via intuitive menu, which can be accessed via digital colour touch-display and browser remote control. Therefore, all processing conditions such as net energy, total energy, amplitude, time, pressure and temperature are automatically recorded on a built-in SD-card. This allows you to revise and compare previous sonication runs and to optimize the duckweed extraction process to highest efficiency.
Hielscher Ultrasonics systems are used worldwide for the manufacturing of high-quality botanical extracts. Hielscher industrial ultrasonicators can easily run high amplitudes in continuous operation (24/7/365). Amplitudes of up to 200µm can be easily continuously generated with standard sonotrodes (ultrasonic probes / horns). For even higher amplitudes, customized ultrasonic sonotrodes are available. Due to their robustness and low maintenance, our ultrasonic extraction systems are commonly installed for heavy duty applications and in demanding environments.

Contact us now to learn more about ultrasonic duckweed extraction, our ultrasonic extraction systems and price information! Our well-experienced staff will be glad to discuss your application and processing requirements with you!
The table below gives you an indication of the approximate processing capacity of our ultrasonicators: