Peas (Pisum sativum L.) are not just a common vegetable but a nutritional powerhouse driving the global shift toward plant-based proteins. With rising concerns about environmental sustainability, food allergies, and the demand for affordable protein, scientists are unlocking peas’ full potential.
A groundbreaking 2025 study by Sonia Kumar and Marianne Su-Ling Brooks at Dalhousie University, published in Separation and Purification Technology, introduces two-stage foam fractionation, a method that efficiently recovers and purifies pea proteins while boosting their functional properties.
The Growing Demand for Sustainable Plant-Based Proteins
The global demand for plant-based proteins is surging due to their lower environmental impact compared to animal-derived proteins. Peas, in particular, are gaining attention for being low-allergenic, water-efficient, and rich in essential nutrients like lysine.
However, traditional extraction methods like wet fractionation (using chemicals and high energy) and dry milling (mechanical separation) face significant challenges.
- For instance, commercial pea protein flour contains only 19.8% protein, and wet fractionation loses up to 30% of proteins in wastewater.
These methods also yield proteins with poor solubility, limiting their use in products like vegan cheeses or protein drinks. This is where pea protein foam fractionation shines.
Unlike conventional techniques, foam fractionation uses air bubbles to concentrate proteins without chemicals, achieving 86.7% recovery and 5.8-fold purity improvement.
This method not only addresses efficiency gaps but also enhances the proteins’ functionality, making it a game-changer for the food industry.
How Pea Protein Foam Fractionation Works
Foam fractionation relies on a simple principle: proteins act as natural surfactants, sticking to air bubbles in liquid solutions.
When air is bubbled through a protein-rich solution, proteins cling to the bubbles, rise as foam, and are collected as a concentrated liquid. The Dalhousie team optimized this into a two-stage process to maximize both recovery and purity.
- In the first stage, researchers focused on extracting maximum protein from diluted pea flour. They tested variables like protein concentration, pH, airflow rate, and liquid volume.
A concentration of 1.0 g/L, pH 4.5 (the isoelectric point where proteins are least soluble), airflow of 800 mL/min, and a liquid volume of 4000 mL delivered the best results: 86.7% recovery and doubled protein concentration.
- The second stage further purified the extracted proteins. By reducing airflow to 300 mL/min and using a smaller liquid volume (1500 mL), the team achieved a 5.8-fold purity increase, reaching 57.8% protein content—close to commercial pea protein isolates.
This two-step approach not only improves yield but also reduces water and energy use, making it environmentally friendly.
Transforming Functional Properties of Pea Proteins
The study’s most exciting outcome is how foam fractionation enhances pea proteins’ functional properties—traits that determine their performance in foods. By exposing proteins to air bubbles, the process alters their structure, revealing hidden hydrophobic and hydrophilic regions.
This structural shift leads to remarkable improvements in solubility, foaming, emulsification, and water/oil binding. For example, untreated pea protein flour dissolves poorly, especially at neutral pH.
After foam fractionation, solubility at pH 8 jumped from 2.60 mg/mL to 4.90 mg/mL, an 88% increase. This improvement allows smoother textures in plant-based beverages.
Similarly, foaming capacity doubled from 98.3% to 210.0%, enabling fluffier vegan desserts. Emulsification—critical for products like mayonnaise—also improved, with emulsion stability rising to 74.6% after 90 minutes.
Oil and water binding saw dramatic boosts too. The treated proteins could hold 8.5 grams of oil per gram of protein, a 4x increase, reducing sogginess in baked goods.
Water retention tripled, enhancing juiciness in meat alternatives. These advancements position foam-fractionated pea proteins as versatile ingredients for diverse food applications.
The Science Behind Structural Changes
To understand why foam fractionation works, the team used SDS-PAGE gel electrophoresis, a technique that separates proteins by size. They discovered that key pea proteins like legumin (11S) and vicilin (7S) broke into smaller subunits during the process.
- Legumin, a large hexameric protein, split into fragments (60 kDa, 38–40 kDa, and 18–24 kDa), while vicilin fragmented into lighter subunits (25–30 kDa).
These structural changes exposed hydrophobic regions, allowing proteins to form stronger networks at air-water or oil-water interfaces. This explains the enhanced emulsification and foaming properties.
Essentially, foam fractionation “unlocks” hidden traits in pea proteins, transforming them into high-performance ingredients.
Environmental and Economic Benefits of Foam Fractionation
Traditional protein extraction methods like wet fractionation and dry milling are resource-heavy, relying on chemicals, high energy, and large water volumes. In contrast, pea protein foam fractionation operates at room temperature, uses no harsh chemicals, and recycles residual liquids, slashing water waste.
For instance, the Stage 2 residual solution (1.04 g/L protein) can be reused in Stage 1, minimizing freshwater use. Economically, this method reduces costs by eliminating expensive steps like centrifugation or membrane filtration.
Manufacturers gain access to premium, functional proteins at lower production costs, making plant-based foods more affordable. Additionally, upcycling dilute protein streams from existing processes cuts waste, aligning with circular economy principles.
Challenges and Future Directions
While promising, scaling pea protein foam fractionation faces hurdles. Proteins from damaged peas or mixed crops may behave unpredictably, requiring tailored adjustments. Industrial-scale systems need precise airflow control to maintain foam stability. Regulatory approval for food-grade use also demands rigorous safety and consistency testing.
To address these challenges, researchers suggest combining foam fractionation with techniques like pH-shifting or ultrasound to further enhance functionality.
Hybrid models integrating traditional and foam-based methods could maximize yield and adaptability. These innovations could extend beyond peas to lentils, chickpeas, and even algae, broadening the impact on sustainable food systems.
Conclusion: Pioneering Sustainable Food Systems
The Dalhousie study marks a milestone in sustainable protein processing. By transforming a simple, eco-friendly technique into a protein-enriching powerhouse, foam fractionation redefines how we approach plant-based ingredients.
As lead researcher Sonia Kumar notes, “The proteins we recovered weren’t just purer—they worked better than anything we’ve seen before.” For consumers, this means tastier, healthier plant-based foods. For the planet, it’s a leap toward resource-efficient agriculture.
As the demand for sustainable proteins grows, innovations like foam fractionation will play a pivotal role in shaping greener, more equitable food systems.
Power Terms
Pea Protein Flour (PPF): A powder made by grinding dried peas, containing about 19.8% protein. It’s important because it’s a plant-based protein source used in foods, especially for people who avoid animal products or allergens like soy or gluten.
Foam Fractionation: A method to separate proteins by bubbling air through a liquid, causing proteins to stick to bubbles and form foam. This is important because it’s a low-energy way to concentrate proteins from dilute solutions, like pea flour mixtures.
Enrichment Ratio (E): Measures how much more concentrated the protein becomes in the foam compared to the original liquid. A higher ratio means more protein is collected, which is useful for making purer protein ingredients.
Recovery Percentage (R): The amount of protein successfully collected from the original solution. High recovery means less waste, making the process efficient for industries.
Functional Properties: Traits like solubility, foaming, and emulsifying that determine how proteins behave in food (e.g., making vegan cheese creamy). Improving these helps pea proteins work better in recipes.
pH: A scale measuring how acidic or alkaline a solution is. Proteins behave differently at different pH levels; for example, pea proteins clump at pH 4.5 (their isoelectric point), which helps separate them.
Isoelectric Point (pI): The pH where a protein has no net charge and becomes insoluble. For pea protein, this is pH 4.5. It’s important because proteins are easiest to separate at this pH.
Air Flow Rate: How fast air is bubbled into the liquid during foam fractionation. Faster airflow can recover more protein but may reduce purity, so balancing speed is key.
Liquid Loading Volume: The amount of liquid processed in the foam column. Larger volumes improve protein recovery but may dilute the foam, affecting enrichment.
Emulsification: The ability to mix oil and water (e.g., in salad dressings). Pea proteins with good emulsification can replace eggs or dairy in vegan foods.
Foaming Capacity: How well proteins create foam (important for desserts like mousse). Foam fractionation improves this by exposing proteins to air bubbles.
Oil Holding Capacity (OHC): How much oil a protein can absorb. High OHC is useful for fatty foods like plant-based meats, giving them a juicier texture.
Water Holding Capacity (WHC): A protein’s ability to retain water. Foods with high WHC stay moist, like veggie burgers or baked goods.
Soluble Protein Content: The amount of protein that dissolves in water. Higher solubility means proteins mix better into drinks or smoothies.
Alkaline Extraction: Using a high-pH solution to dissolve proteins from pea flour. This step separates protein from starch but uses lots of water and energy.
Dry Fractionation: Separating proteins by milling and air instead of water. It’s eco-friendly but yields less pure protein than wet methods.
Wet Fractionation: Using water to extract proteins, often with chemicals. It’s efficient but creates wastewater, making foam fractionation a greener alternative.
Surface-Active Compounds: Molecules (like proteins) that gather at liquid-air interfaces. This property lets them stabilize foams or emulsions in foods.
Bovine Serum Albumin (BSA): A protein used as a reference in lab tests. Comparing pea proteins to BSA helps measure their concentration accurately.
SDS-PAGE Electrophoresis: A lab technique to separate proteins by size. It showed pea proteins in the foamate were purer than in the original flour.
Legumin and Vicilin: The two main proteins in peas. They affect texture and solubility; foam fractionation concentrates them for better food applications.
Freeze-Drying: Removing water from proteins by freezing and vacuuming. It preserves protein quality for storage without losing functionality.
pH Shifting: Changing pH to unfold and refold proteins, improving solubility. Combined with foam fractionation, it boosts pea protein performance.
Protein Yield: The amount of protein extracted from raw material. High yield means more product from less input, saving costs.
Two-Stage Process: First, recover proteins (Stage 1); then, concentrate them further (Stage 2). This method balances high recovery and purity, ideal for industry.
Reference:
Kumar, S., & Brooks, M. S.-L. (2025). Enrichment and recovery of pea (Pisum sativum L.) proteins using foam fractionation for simultaneous enhancement of their functional properties. Separation and Purification Technology, 364, 132578. https://doi.org/10.1016/j.seppur.2025.132578
