Proteins are vital for human health and play a crucial role in food production. They are macromolecules made of amino acids, which are the building blocks of life. In food science, proteins contribute to texture, stability, and nutrition.
For example, they stabilize emulsions (mixtures of oil and water, like mayonnaise), form foams (as in whipped cream), and bind water in baked goods. For decades, animal proteins—derived from milk, eggs, and meat—have dominated the food industry due to their superior functionality and balanced amino acid profiles. However, the environmental cost of animal agriculture is staggering.
57% of greenhouse gas emissions from food production come from animal-based sources, contributing heavily to climate change. In contrast, plant-based proteins generate half the emissions, making them essential for building sustainable food systems. Among plant proteins, hemp seed protein has emerged as a standout candidate.
Hemp seeds are the seeds of the Cannabis sativa plant, which is distinct from marijuana due to its low THC content (the psychoactive compound). Hemp protein boasts a high protein content (over 85% in isolates), a complete amino acid profile (containing all nine essential amino acids), exceptional digestibility (91%), and low allergenic risk compared to soy or nuts.
Despite these advantages, hemp protein struggles in food applications due to poor surface hydrophobicity (a measure of how well proteins interact with fats) and large, clumped particles that reduce solubility. A groundbreaking 2025 study in Food Chemistry Advances tackles these limitations by combining roasting, high-pressure homogenization, and alkaline pH-shifting to transform hemp protein into a high-performance ingredient.
The Nutritional and Environmental Benefits of Hemp Seed Protein
Hemp seeds are a nutritional powerhouse. When dehulled (the outer shell removed), they contain over 50% protein by weight, and advanced processing techniques can refine this into isolates with over 85% purity. Protein isolates are concentrated forms of protein where most non-protein components (like fats and carbohydrates) are removed.
Unlike many plant proteins, hemp provides all nine essential amino acids, including lysine and leucine, which are often scarce in plant-based diets. Lysine supports collagen production and calcium absorption, while leucine is critical for muscle repair.
Its digestibility (91%) surpasses soy protein (around 80%) and matches animal proteins, making it ideal for athletes and health-conscious consumers. The two main proteins in hemp seeds are edestin and albumin.
Edestin, making up 60–80% of the total protein, is a globular protein rich in sulfur-containing amino acids like cysteine, which supports muscle repair and immune function.
Albumin, a water-soluble protein, contributes antioxidant properties, protecting cells from damage caused by free radicals. Despite these strengths, hemp protein’s tightly folded structure limits its functionality. For instance, in plant-based cheese, proteins must emulsify fats and water to create a smooth texture, while vegan desserts require proteins to foam like egg whites.
Traditional hemp protein fails here due to low surface hydrophobicity (a protein’s ability to attract and bind to fats) and large aggregates (clusters of proteins stuck together) that hinder solubility.
Science-Backed Protein Enhancement Methods
The 2025 study tested how roasting, high-pressure homogenization, and alkaline pH-shifting—alone and combined—alter hemp protein’s structure and performance. Below is a detailed explanation of each method and its scientific rationale:
1. Roasting involves heating dehulled hemp seeds at 220°C for 20 minutes using infrared technology. Roasting is a dry-heat treatment that disrupts hydrogen bonds and other weak interactions in proteins, partially unfolding their structure. This process exposes hidden hydrophobic (water-repelling) regions, which are crucial for interacting with fats.
For example, roasting peanut protein under similar conditions boosted emulsification activity by 30%, suggesting a similar mechanism for hemp.
2. High-pressure homogenization (HPH) is a mechanical process that blasts protein solutions through a narrow valve at 40 MPa (400 times atmospheric pressure) for three cycles. The intense shear forces (friction between fluid layers) and cavitation (formation and collapse of bubbles) physically break large protein clumps into nanoparticles.
For example, HPH reduced kidney bean protein aggregates from 10 micrometers to 200 nanometers, significantly improving solubility and functionality. Smaller particles have a larger surface area, allowing proteins to interact more effectively with water, oil, or air.
3. Alkaline pH-shifting involves soaking proteins in a high-pH solution (pH 12) for 10 minutes before neutralizing to pH 7. pH measures acidity or alkalinity on a scale of 0–14, with 7 being neutral. Extreme pH levels denature proteins (unfold their structure) by disrupting ionic bonds and electrostatic interactions.
Upon neutralization, proteins refold into a “molten globule” state—a flexible, partially unfolded structure with exposed hydrophobic patches. This state enhances functionality because the protein is more flexible and can bind to fats or air bubbles more easily.
Alkaline treatment is more effective than acidic methods, increasing soy protein’s emulsifying activity by 2.5-fold in prior research. The researchers tested five protein samples: untreated hemp protein (C), roasted hemp protein (R), roasted + homogenized protein (RH), roasted + pH-shifted protein (pH12-R), and roasted + homogenized + pH-shifted protein (pH12-RH).
Breakthrough Findings in Protein Modification
Using advanced tools like spectroscopy (studying light-matter interactions), microscopy (imaging tiny structures), and gel electrophoresis (separating proteins by size), the team uncovered how treatments modified hemp protein at molecular and functional levels.
1. Particle Size and Surface Charge
Mean Hydrodynamic Diameter (D): This measures the average size of protein particles in solution. Untreated hemp protein formed large aggregates due to weak repulsion between particles. Roasting reduced particle size to 2.4 micrometers, while combining roasting, homogenization, and pH-shifting shrank particles to 143 nanometers—35 times smaller than the control. Smaller particles dissolve more easily and stabilize emulsions by coating oil droplets uniformly.
ζ-Potential: This measures the electrical charge on protein surfaces. A higher absolute value (positive or negative) indicates stronger repulsion between particles, preventing clumping. Untreated protein had a slight positive charge (+3.56 mV), but pH12-RH dropped to -22 mV, creating strong repulsive forces that enhance stability.
2. Structural Changes at the Molecular Level
Secondary Structure: Proteins have four levels of structure. The secondary structure includes α-helices (coiled chains) and β-sheets (folded strands). Circular dichroism spectroscopy revealed that treatments reduced α-helix content from 24.04% in control to 11.94% in pH12-RH, while increasing β-sheets (from 19.06% to 28.74%) and random coils (flexible, disordered regions).
More β-sheets and random coils improve flexibility, allowing proteins to adapt to interfaces like oil-water boundaries. Tertiary Structure: This refers to the 3D shape of the protein. Fluorescence tests showed a 9 nm redshift (from 327 nm to 336 nm) and a 2.5-fold increase in intensity, indicating that buried hydrophobic amino acids like tryptophan became exposed.
Surface hydrophobicity, measured using a fluorescent dye called ANS (8-anilino-1-naphthalenesulfonic acid), surged from 137.86 in control to 472.44 in pH12-RH—a 3.4-fold increase. Hydrophobic regions are critical for binding to fats or air bubbles.
3. Functional Performance
- Foaming Capacity: This measures how much foam a protein can create. Untreated hemp protein (C) had poor foaming ability (10%), but pH12-RH reached 72.4%—comparable to egg whites. Foam stability (how long foam lasts) also improved from 15% after 60 minutes (C) to 68% (pH12-RH).
- Emulsifying Activity Index (EAI): This quantifies how well proteins stabilize oil-water mixtures. pH12-RH achieved 60 m²/g, a 5-fold increase over the control (12 m²/g).
- Emulsion Stability Index (ESI): This measures how long emulsions resist separation. pH12-RH extended stability from 4 minutes (C) to 22 minutes.
- Microscopy Insights: Untreated protein produced clumped, unstable droplets (10–50 micrometers), while pH12-RH created uniform, small droplets (5–14 micrometers) with no flocculation (clumping).
How Combined Treatments Create Synergistic Effects
The study highlights how roasting, homogenization, and pH-shifting work together to amplify results. Roasting acts as a “pre-treatment,” loosening protein structures and exposing hydrophobic regions. High-pressure homogenization then breaks these pre-treated proteins into nanoparticles, increasing surface area.
Finally, alkaline pH-shifting fully unfolds proteins, allowing them to refold into a molten globule state—a flexible, open conformation ideal for interacting with fats and water.
For example, combining all three treatments (pH12-RH) reduced particle size to 143 nanometers, outperforming individual treatments like roasting + pH-shifting (155 nanometers). Similarly, surface hydrophobicity reached 472.44 in pH12-RH, compared to 431.66 in pH12-R. This synergy is key to achieving the dramatic improvements in functionality.
Implications for the Food Industry and Beyond
The findings have far-reaching implications for plant-based food innovation. With 72% foaming capacity and 5-fold higher emulsifying activity, treated hemp protein can replace animal proteins in products like:
- Vegan Whipped Cream: Stable foams mimic dairy-based toppings.
- Salad Dressings: Emulsions stay mixed without separating.
- Plant-Based Meats: Improved water-binding creates juicier textures.
For instance, egg whites—prized for their foaming ability—could be substituted with pH12-RH hemp protein in meringues or cakes, reducing reliance on poultry farming. Environmentally, adopting hemp protein could significantly cut emissions.
Replacing 10% of global egg protein with hemp might reduce CO₂ emissions by 1.2 billion tons annually, based on FAO data. Additionally, hemp cultivation requires less water and pesticides than soy or almonds, making it a greener crop overall.
Challenges and Future Research Directions
While promising, scaling these methods requires addressing practical hurdles:
- Energy Costs: High-pressure homogenization consumes ~5 kWh per ton of protein. Optimizing pressure cycles or using renewable energy could reduce this.
- Sensory Properties: Roasting may impart a nutty flavor, which might clash with neutral-tasting products like plant-based milk. Blending with other proteins or flavor masking could help.
- Production Costs: Combined treatments may raise costs by 15–20%, but bulk processing and technological advances could lower expenses over time.
Future research could explore several promising directions to further enhance the functionality of hemp seed protein. One approach is enzymatic modification, where enzymes like proteases are used to partially pre-digest proteins, improving their solubility and digestibility.
Another area is the use of ultrasound technology, which offers a low-energy alternative to conventional homogenization for forming protein nanoparticles, potentially improving processing efficiency. Additionally, research should focus on the long-term stability of these modified proteins, assessing how they perform in real food systems over time to ensure consistent quality, texture, and nutritional value.
Conclusion
The 2025 study shows that with targeted physical and chemical treatments, hemp seed protein can match animal proteins in functionality. Key improvements include reduced particle size, increased hydrophobicity, and enhanced emulsifying ability. This positions hemp as a promising, eco-friendly protein source. As climate challenges grow, innovations like this are vital for creating sustainable, nutritious diets from underused crops.
Power Terms
Hemp Seed Protein: Proteins extracted from hemp seeds, known for being plant-based and rich in essential amino acids. These proteins are important for vegan diets and food products like protein powders or meat substitutes. Example: Hemp protein added to smoothies for nutrition.
Roasting: A heat treatment process (e.g., heating seeds at 220°C) that changes protein structure. It improves functionality, like emulsification, and enhances flavor. Example: Roasted peanuts used for better-tasting peanut butter.
High-Pressure Homogenization: A mechanical method where proteins are forced through a narrow space under high pressure. This breaks large particles into smaller ones, improving solubility and texture. Used in dairy products like milk to prevent fat separation.
Alkaline pH-Shifting: Adjusting a protein solution to a high pH (e.g., pH 12) to unfold proteins, then neutralizing it. This exposes hidden parts of the protein, improving its ability to mix with water or oil. Example: Making soy protein easier to digest.
ζ-Potential (Zeta Potential): A measure of the electrical charge on protein particles in liquid. A high ζ-potential (e.g., -30 mV) means particles repel each other, keeping mixtures stable. Important for preventing clumping in sauces or dressings.
Hydrodynamic Diameter (Dh): The size of a protein particle in liquid, including water attached to it. Smaller Dh (e.g., 150 nm) means proteins mix better. Measured using dynamic light scattering.
Electrophoresis: A lab technique to separate proteins by size or charge. For example, SDS-PAGE uses electricity to move proteins through a gel, creating bands that show different protein sizes.
Dynamic Light Scattering (DLS): Shines a laser on particles in liquid to measure their size. Used to check if proteins are clumped or evenly dispersed. Example: Testing nanoparticle sizes in medicines.
Fourier Transform Infrared Spectroscopy (FTIR): A tool that identifies protein structures by measuring how they absorb infrared light. Detects changes in bonds, like shifts in amide I bands (1600–1700 cm⁻¹), indicating protein unfolding.
Circular Dichroism Spectroscopy: Measures how proteins twist light to determine their shape (e.g., α-helix or β-sheet). Helps researchers see if treatments like heating damage protein structures.
SDS-PAGE: A type of electrophoresis that uses detergent (SDS) to separate proteins by size. Example: Checking if a protein isolate is pure or has contaminants.
Surface Hydrophobicity: How “water-repelling” a protein’s surface is. Higher hydrophobicity (e.g., measured with a fluorescent dye) helps proteins stabilize foams or emulsions.
Foaming Capacity: How much foam a protein can create when whipped. Calculated as: (Foam volume after whipping ÷ Original liquid volume) × 100. Important for desserts like mousse.
Foam Stability: How long foam lasts before collapsing. Formula: (Foam volume after 1 hour ÷ Initial foam volume) × 100. Critical for products like whipped cream.
Emulsifying Activity Index (EAI): Measures how well proteins mix oil and water. Formula: 2 × (Turbidity) ÷ (Protein concentration × Oil fraction × 1000). Higher EAI means better emulsions, like in mayonnaise.
Emulsion Stability Index (ESI): Tests how long an emulsion stays mixed. Formula: (Initial absorbance × 10) ÷ Change in absorbance over time. Used to predict shelf life of salad dressings.
Molten Globule State: A partially unfolded protein structure that retains some shape but is more flexible. Created by treatments like pH-shifting, it improves functionality for food applications.
α-Helix: A coiled protein structure (like a spring) stabilized by hydrogen bonds. Provides rigidity. Example: α-helix in hair keratin. Roasting reduces α-helix content, making proteins more flexible.
β-Sheet: A flat, zigzag protein structure. Adds strength but limits flexibility. Example: β-sheets in silk. Treatments like homogenization may increase β-sheets in hemp protein.
β-Turn: A tight U-shaped bend in a protein chain, linking secondary structures. Helps proteins fold into compact shapes.
Random Coil: Unstructured, flexible regions in proteins. More random coils (e.g., after pH-shifting) can improve mixing with other ingredients.
Greenhouse Gas Emissions: Gases like CO₂ that trap heat in the atmosphere. Plant proteins (e.g., hemp) produce fewer emissions than animal proteins, making them eco-friendly.
Plant-Based Proteins: Proteins from plants like soy, peas, or hemp. Used as sustainable alternatives to meat. Example: Vegan burgers made with pea protein.
Edestin: The main protein in hemp seeds (60–80% of total protein). A globular protein rich in essential amino acids, similar to animal proteins.
Albumin: A water-soluble protein in hemp seeds and egg whites. Helps transport nutrients and stabilizes emulsions.
Reference:
Zaaboul, F., Borah, P. K., & di Bari, V. (2025). Impact of roasting, high-pressure homogenization, and alkaline pH-shifting on hemp seed protein functionality. Food Chemistry Advances, 6, Article 100943. https://doi.org/10.1016/j.focha.2025.100943
