Rapeseed Cake Valorization into Bioplastics Based on Protein Amyloid Fibrils

Abstract

Biodegradable polymers obtained from renewable resources are urgently needed to help mitigating the environmental burden of plastic pollution. Herein, a green process is developed to obtain protein‐based bioplastics through valorization of rapeseed cake. First, the effects of different protein extraction protocols are investigated, including water extraction at pH values from 1 to 12 and salt extraction with isoelectric point precipitation (IP), on proteins profile and sample composition. It is demonstrated that alkaline extraction at pH 12 results in the highest extraction yields of proteins (≈70%) and total solutes (≈50%). The IP results in lower yields but in highest protein purity of ≈80%. Alkaline extraction at pH 10.5 results in the extraction of 36% total solutes and ≈50% of proteins, with a protein profile similar to that obtained by IP, rich in α and β polypeptides chains of cruciferin. AFM analysis shows that samples containing cruciferin allow self‐assembly into mature amyloid fibrils upon incubation. Rapeseed amyloids are blended with polyvinyl alcohol and glycerol to develop bioplastics films that are characterized by decreased water absorption, higher water contact angle, and elongation at break >600%, more than double compared to films obtained from native monomers.

From Soy Waste to Bioplastics: Industrial Proof of Concept

“…The mechanical properties measured here are similar to those reported previously in other systems based on protein nanofibrils from other protein sources. [21][22][23]37 The soy-based film, however, has a lower tensile strength in both directions compared with the other materials, suggesting its suitability in those packaging applications that require high flexibility and elongation but not necessarily high mechanical strength.…”

“…We use these soy nanofibrils as building blocks to fabricate sustainable bioplastic films in combination with a biodegradable polymer, methylcellulose (MC), and a plasticizer, glycerol. Amyloids’ intrinsic attributes, including their distinctive aspect ratio and an abundance of functional group terminals, allow hydrogen-bond interaction formation within the films, reinforcing their mechanical properties. − …”

“…These include the high costs related to both raw materials and production processes, particularly when compared with their petroleum-based counterparts. Additionally, protein-based bioplastics often exhibit inferior mechanical and barrier properties, along with low water stability, due to the intrinsic hydrophilic nature of most native proteins. − To surmount these limitations, researchers are trying to enhance the water stability, mechanical strength, and processability of protein-based materials, using different techniques ranging from cross-linking to protein monomer hydrolysis. − Moreover, recent research has demonstrated that the conversion of protein monomers into self-assembled amyloid fibrils offers a gateway to the creation of bioplastic films endowed with extraordinary properties. − These amyloid fibrils, characterized by unique functionalities and mechanical, thermal, and chemical stabilities, can be obtained from a broad range of proteins, including some abundantly available in industrial side streams . These features altogether make protein nanofibrils ideal candidates for engineering versatile biomaterials with a broad range of applications, including membranes for water purification, aerogels, and composite materials. , …”

Hybrid Amyloid–Chitin Nanofibrils for Magnetic and Catalytic Aerogels

“…In the quest for solutions to this crisis, biopolymers emerge as a promising alternative, particularly when derived from food waste, aligning with the principles of a circular economy. , Biopolymers such as proteins and polysaccharides, abundant in agri-food biomass and sidestreams, offer a compelling opportunity to engineer sustainable advanced materials for addressing global challenges. ,− …”

Functional Amyloids: The Biomaterials of Tomorrow?

“…The obtained rapeseed cake amyloids‐based bioplastics rendered films that displayed improved properties when blended with polyvinyl alcohol and glycerol. [ 99 ]…”