In the quest for sustainable nutrition, a tiny aquatic plant with massive potential is making waves
Duckweed, often called "water lentil," is a tiny floating aquatic plant that grows on still or slow-moving freshwater surfaces worldwide. Despite its modest size, this plant is generating enormous excitement among scientists, nutritionists, and environmentalists. As the global population continues to grow—projected to reach 9.7 billion by 2050—the demand for sustainable protein sources is becoming increasingly urgent 6 .
Traditional animal-based proteins place tremendous strain on our environment, accounting for approximately 26% of ice-free land use and significant greenhouse gas emissions 6 . Meanwhile, popular plant proteins like soy have their own environmental drawbacks, including deforestation and soil erosion 9 .
Perhaps most impressively, duckweed species contain 16-45% protein by dry weight and provide all eight essential amino acids in proportions comparable to legumes and other high-quality protein sources 1 4 7 .
Despite its impressive nutritional profile, duckweed faces a significant hurdle: the bioavailability of its nutrients. Just because a plant contains protein doesn't mean our bodies can efficiently access and utilize it.
The rigid cell walls of plants can trap valuable proteins, making them difficult for our digestive systems to break down.
Like many plants, duckweed contains compounds that may interfere with nutrient absorption.
Research has shown that humans cannot fully utilize all available proteins from a single serving of boiled duckweed due to these structural barriers 7 .
One of the most promising approaches to improving duckweed's digestibility is enzymatic hydrolysis. This process uses specific enzymes to break down proteins into smaller peptides and amino acids, making them easier for our bodies to absorb.
A groundbreaking study published in 2024 demonstrated the potential of this approach by treating duckweed powder with four different enzymes: pepsin, chymotrypsin, papain, and trypsin . The results were impressive—even without prior extraction or concentration of proteins, these enzymes successfully hydrolyzed the duckweed, with degrees of hydrolysis ranging from 3% to 9% .
Most notably, the resulting hydrolysates showed significant ACE inhibitory activity, with some fractions increasing this activity by 6- to 8-fold. Since ACE (angiotensin-converting enzyme) plays a key role in regulating blood pressure, these findings suggest duckweed hydrolysates may offer antihypertensive benefits in addition to improved digestibility .
| Enzyme Used | Degree of Hydrolysis | ACE Inhibition (IC50 value) | Key Observations |
|---|---|---|---|
| Pepsin | Not specified | Not specified | Effective hydrolysis |
| Chymotrypsin | Not specified | 0.55-0.70 mg peptides/mL | Highest ACE inhibition |
| Papain | Not specified | 0.55-0.70 mg peptides/mL | High ACE inhibition |
| Trypsin | Not specified | Not specified | Effective hydrolysis |
Another powerful approach involves combining enzymatic hydrolysis with microbial fermentation 2 . This synergistic process not only breaks down complex proteins but can also:
This combined approach is particularly valuable for aquaculture applications, where duckweed shows great promise as a sustainable fish feed ingredient 2 .
Beyond enzymatic and fermentation approaches, researchers are exploring various physical and chemical processing methods to improve duckweed's digestibility, including:
These processing methods aim to break down duckweed's resilient cell structure while maintaining the nutritional quality of its proteins.
To better understand how scientific research is unlocking duckweed's potential, let's examine a key experiment in detail.
The 2024 study conducted by researchers at Université Laval focused on producing antihypertensive peptides from duckweed through enzymatic hydrolysis :
Defatted duckweed powder was suspended in distilled water and left to solubilize for 16 hours at 10°C under constant stirring
The solution was heated to 37°C and adjusted to specific pH levels optimal for each enzyme:
Proteases were added at a ratio of 1:100 (enzyme to substrate) and the hydrolysis proceeded for 4 hours with constant pH maintenance
After hydrolysis, samples were centrifuged to separate soluble supernatants from insoluble pellets
Researchers measured the degree of hydrolysis, identified peptide sequences, quantified phenolic compounds, and evaluated ACE inhibitory activity
| Reagent/Equipment | Function in Experiment | Significance |
|---|---|---|
| Defatted duckweed powder | Primary protein source | Ensures consistent starting material by removing fats that could interfere with hydrolysis |
| Proteases (pepsin, chymotrypsin, papain, trypsin) | Break down proteins into smaller peptides | Different enzymes target different cleavage sites, generating diverse peptide profiles |
| pH control systems (HCl, NaOH) | Maintain optimal enzyme activity | Enzyme function is highly pH-dependent; precise control ensures efficient hydrolysis |
| Centrifuge | Separate soluble and insoluble fractions | Allows researchers to analyze different components of the hydrolysate separately |
| UPLC-MS system | Identify peptide sequences | Advanced analytical technique that reveals the specific protein fragments generated |
The experiment yielded several important findings:
All four enzymes effectively broke down duckweed proteins without needing prior extraction or concentration steps
Researchers identified 485 distinct peptide sequences across the hydrolysates, with only 51 common to multiple hydrolysates
Enzymatic treatment released phenolic compounds at concentrations up to 11 mg gallic acid equivalent per gram of sample
The chymotryptic hydrolysate and papain supernatant showed the strongest ACE inhibitory activity—a 6- to 8-fold improvement
| Bioactivity | Findings | Potential Health Applications |
|---|---|---|
| ACE inhibitory activity | 6- to 8-fold increase in inhibition after hydrolysis | Hypertension management, cardiovascular health |
| Release of phenolic compounds | Up to 11 mg GAE/g sample released | Antioxidant protection, reduced oxidative stress |
| Bioactive peptide production | 485 distinct peptide sequences identified | Various health benefits including potential antimicrobial, antidiabetic effects |
As research progresses, duckweed is gradually making its way into commercial applications. Several companies are already exploring its potential:
Has developed a duckweed protein isolate with physical properties similar to egg whites, creating vegan products that replicate textures typically associated with animal-based ingredients 7 .
Companies are pursuing novel food authorization for duckweed species, though regulatory review is ongoing 9 .
The global duckweed-based protein market is projected to grow at a compounded annual growth rate of 11.0% over the next decade, potentially reaching USD 161.32 million 7 .
Duckweed represents a fascinating convergence of sustainability, nutrition, and food innovation. This humble aquatic plant, long overlooked in Western diets, offers a promising solution to multiple challenges: feeding a growing population sustainably, reducing environmental impact, and providing high-quality nutrition.
The scientific breakthroughs in improving duckweed's digestibility and bioaccessibility—particularly through enzymatic hydrolysis and fermentation—are unlocking its full potential as a versatile, efficient, and sustainable protein source. As research continues to address remaining challenges and expand applications, we may soon see this tiny green giant playing a significant role in our global food system.
In the words of researchers exploring this promising plant, duckweed species with good properties could be selected through ongoing research and included in human diets after thorough safety testing 6 . The journey from laboratory research to mainstream adoption may still be underway, but the path forward is increasingly clear—and undoubtedly green.