Scientists Turn Hemp Protein Into Stronger Bioplastic

Hemp seed oil leaves behind more than an empty press. The remaining oil cake still contains substantial amounts of protein, but this material is often treated as a low-value by-product rather than a feedstock for advanced manufacturing. New research suggests that changing the structure of those proteins could help turn this overlooked residue into biodegradable films for packaging and other products.

In a 2026 study published in Industrial Crops and Products, researchers extracted protein from industrial hemp seed oil cake and chemically modified it with decanoyl chloride, a fatty acid derivative.¹ The treatment produced films that were stronger, more flexible, more thermally stable, and better able to resist moisture than films made from unmodified hemp protein.

The results do not mean that hemp protein is ready to replace conventional plastic. The films were produced under laboratory conditions, and their moisture barrier remained far below that of low-density polyethylene. Still, hemp processors may eventually be able to derive both oil and an engineered material from the same seed crop.

Why Hemp Oil Cake Is an Interesting Raw Material

Hemp is already being evaluated for construction, foods, specialty chemicals, and engineered materials. MyCannabis has examined how hemp fibre is becoming an engineering material and how hemp composites could offer a lower-impact alternative to fiberglass. Protein creates another pathway based on a food-processing by-product rather than the stalk.

After hemp seeds are pressed for oil, the residual cake can contain approximately 34% to 47.9% protein, according to the researchers. Proteins are natural polymers, meaning their long molecular chains can interact to form continuous films. Hemp proteins are particularly interesting because their amino acids provide reactive sites capable of forming hydrogen bonds, hydrophobic interactions, and disulfide linkages.

That chemistry gives hemp protein film-forming ability, but untreated protein films absorb water more readily and possess less mechanical strength than synthetic packaging plastics. They may soften, swell, or lose integrity when exposed to moisture.

The research team therefore did not simply cast hemp protein into a film. It altered the protein itself.

How Chemical Modification Changed the Protein

The researchers used acylation, a reaction that attaches fatty-acid-derived groups to reactive amino groups in the protein. Hemp protein was treated with three concentrations of decanoyl chloride: 2.8, 5, and 7.5 millimoles per gram of protein. An untreated formulation served as the control.

The degree of modification increased with the dose, reaching 60.53% at the highest concentration. Spectroscopy confirmed changes involving the protein’s amide regions, while measurements of particle size and electrical charge indicated that treatment changed how protein particles interacted in solution.

Microscopy showed that the modified films generally had smoother surfaces, smaller pores, and more compact internal structures. With fewer open pathways through the material, water vapour had a more difficult route across the film.

More Modification Was Not Always Better

The results reveal a useful engineering lesson: there was no single formulation that maximized every property. The 5 mM/g treatment produced the greatest tensile strength at 3.9 MPa, compared with 2.1 MPa for the control. Its Young’s modulus, a measure of stiffness, reached 37.6 MPa, more than twice the control value of 18.1 MPa.

At 7.5 mM/g, tensile strength and stiffness declined from their peaks, although both remained above the untreated film. The researchers attributed this partly to bulky hydrophobic groups interfering with hydrogen bonding and promoting some aggregation. At the same time, the highest treatment produced the most flexible film, with elongation at break increasing from 206% in the control to 384%.

This tradeoff could become commercially useful. A rigid tray, flexible wrapper, and agricultural film do not require identical properties. Manufacturers could adjust the modification level around a specific application.

The main performance changes included:

• Higher strength and stiffness, particularly at the intermediate treatment
• Greater flexibility as the level of modification increased
• Lower moisture content, swelling, solubility, and water vapour permeability
• Higher thermal denaturation temperatures in the more heavily modified films

Moisture Resistance Improved, but a Large Gap Remains

Water vapour permeability declined from 2.17 × 10^-10 in the untreated film to 1.34 × 10^-10 g m^-1 s^-1 Pa^-1 at the highest treatment, a reduction of approximately 38%. Moisture content, water solubility, and swelling also fell as more decanoyl chloride was used.

However, all samples still had water contact angles below 90 degrees, meaning their surfaces remained hydrophilic rather than truly water-repelling. The modified film’s water vapour permeability was also much higher than the 0.009 × 10^-10 value the paper cited for low-density polyethylene.

That gap does not make the research irrelevant. It narrows the credible application range. A hemp protein film may be more suitable for products with limited moisture exposure, multilayer packaging where another material supplies the primary barrier, agricultural products, pharmaceutical coatings, or disposable items designed for short service lives. It is less convincing as a direct drop-in replacement for polyethylene around moisture-sensitive food.

This is why broad terms such as bioplastic can be misleading. The European Commission distinguishes between biobased, biodegradable, and compostable plastics. A material can belong to one category without satisfying the others, and its environmental value depends on production, use, collection, and disposal.

Soil Disintegration Is Promising but Not Certification

All hemp protein films lost more than 60% of their weight after 40 days in soil and no longer retained their original integrity. The untreated film began breaking apart sooner, while modified films initially resisted degradation because their greater hydrophobicity slowed microbial colonization and moisture penetration. By the end of the trial, however, every hemp formulation had substantially disintegrated. The polyethylene comparison remained intact.

That finding supports biodegradability under the conditions tested, but it should not be described as proof of universal compostability. The experiment measured weight loss during indoor soil burial at an average temperature of 15 degrees Celsius. It did not establish complete conversion into carbon dioxide, water, biomass, and minerals, nor did it test toxicity, home composting, marine degradation, landfill behaviour, or compliance with a packaging standard.

Materials that fragment are not necessarily fully biodegraded. Commercial claims would require standardized testing across defined environments. This is an early materials-development result, not an end-of-life certification.

The Bigger Opportunity Is Whole-Crop Manufacturing

The most important aspect of this research may be its feedstock strategy. Many bioplastics rely on crops or sugars cultivated specifically for polymer production. Hemp oil cake already exists after another product has been made. Using that by-product could distribute agricultural and processing costs across multiple revenue streams while reducing the amount of material treated as waste.

A hemp-processing facility could theoretically produce seed oil, food-grade protein, lower-grade protein for films, and fibrous residues for composites or energy. This cascading use is more compelling than growing hemp solely for disposable packaging.

Related work is already exploring industrial hemp residues for functional packaging systems. Together, these research paths point toward a hemp sector in which processors sell standardized material inputs rather than depending on one volatile end market.

What Must Happen Before Hemp Protein Packaging Scales

The next challenge is translating cast laboratory films into repeatable industrial production. The paper notes that hemp protein composition can vary with cultivar, seed origin, and oil-extraction method. Those differences could change how the protein reacts, making quality control essential.

Researchers must also evaluate oxygen permeability, aroma transfer, food-contact safety, shelf life, chemical recovery, and realistic humidity cycles. Industrial extrusion or coating may yield different properties from laboratory casting. A lifecycle assessment must determine whether the energy, solvents, chemicals, and washing steps preserve a meaningful environmental advantage.

Cost may be the decisive factor. The process extracted protein under alkaline conditions, precipitated it with acid, freeze-dried it, modified it chemically, and used hexane to remove unreacted material. That is appropriate for controlled research, but a commercial process would need fewer steps, solvent recovery, high yields, and consistent inputs.

Even with those limitations, the study expands the conversation around industrial hemp. The crop’s future may not rest on a single miracle product. It may depend on extracting more value from every part of the harvest. If protein left after oil pressing can become a tunable film rather than a low-value residue, hemp could contribute to sustainable packaging through circular processing, not merely through replacing petroleum with another raw material.

References:

¹ Mirpoor, S. F., Cueva Camacho, E., Avitabile, M., Park, M.-K., & Charalampopoulos, D. (2026). Modified hemp protein with fatty acid chloride, an innovative biopolymer for sustainable bioplastic development. Industrial Crops and Products, 252, 124292. https://doi.org/10.1016/j.indcrop.2026.124292