The success of COVID-19 mRNA vaccines has drawn significant interest in developing lipid nanoparticles (LNPs) for gene delivery. Traditional LNP formulations employing polyethylene glycol-based stabilizers have been associated with potential limitations such as immunogenicity and accelerated clearance upon repeated administration. This study introduces LNPs incorporating choline-based ionic liquids (ILs) instead of PEGylated stabilizers for mRNA delivery, particularly to transfect alveolar macrophages. We systematically investigated LNPs incorporated with three choline-based ILs (choline hexanoate, choline aspartate and choline glutamate) including their physicochemical properties, stability and in vitro biological performance. It was found that ILs with amino acid anions, such as aspartate and glutamate, could lead to relatively stable LNP formulations in the absence of PEGylated stabilizers. These IL-incorporated LNPs exhibited notably improved intracellular mRNA transfection in alveolar macrophages compared to copolymer F127-stabilized LNPs. We revealed acidification-induced structural transitions into more ordered inverse lipid mesophases of IL-incorporated LNPs, which may facilitate endosomal escape and efficient mRNA transfection. This LNP property-biological performance relationship study provides valuable insights into designing next-generation nanocarriers for gene delivery. The incorporation of ILs offers a promising avenue to modify the property and performance of LNPs for nanomedicine and mRNA vaccines. This article is part of the discussion meeting issue 'Ionic liquids and the future of soft materials'.

Poly(hydroxyalkanoates) (PHAs) are biobased, compostable polyesters that offer a circular materials pathway for thin film applications, however their high crystallinity and mechanical brittleness limit their suitability for flexible material applications. In this study, 100 – 200 µm thick cast films were produced by blending poly(butylene adipate-co-terephthalate) (PBAT) with poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(3-hydroxybutyrate-co-3- hydroxyvalerate-co-4-hydroxybutyrate) (PHBV-co-P4HB) to improve flexibility. Three 50/50 wt% binary blends of PHA/PBAT were produced via cast film melt extrusion, while films containing 1 – 50 wt% PHBV-co-P4HB with PBAT and 10 wt% CaCO3 were produced to investigate filler effects. PBAT enabled successful melt processing of PHA based thin films. PHBV-co-P4HB/PBAT films exhibited lower crystallinity (12%) than PHB/PBAT (49%) and PHBV/PBAT (51%) blends. After one and a half year of storage, PHB/PBAT and PHBV/PBAT films became more brittle, with Young’s modulus increasing to 15 GPa and 25 GPa, respectively, accompanied by a loss of ductility (elongation at break ≤ 5%). PHBV-co-P4HB/PBAT blends retained flexibility over time, with elongation at break remaining stable (317 ± 66%) and Young’s modulus increasing from 0.36 GPa to 0.69 GPa. Addition of 10% CaCO3 to the PHBV-co-P4HB/PBAT blend increased the Young's modulus and crystallisation temperature, while reducing ductility. Optical photothermal infrared (O-PTIR) spectra obtained from 500 nm spot sizes revealed nanoscale structural heterogeneity not discernible by FTIR, including domain variations and filler effects. P4HB units in PHA copolymers reduced crystallinity and increased elongation at break relative to PHB based materials, with PBAT blending increased flexibility. This work establishes processing–structure–property relationships in cast film extruded PHA/PBAT blends, demonstrating that thin-film bioplastics can achieve mechanical performance and stability comparable to or exceeding polyethylene and polypropylene films.

Variability in the composition and properties of plant proteins presents challenges in developing plant-based meat analogues that have comparable texture to animal-based meats. This study investigated four plant protein isolates to understand the effects of protein source, pH, and salt addition on pasting properties, protein solubility, protein secondary structure, extruder response, and the resulting textural properties. The protein solubilities and paste viscosities of all investigated protein sources were lowest at pH 4. Calcium chloride addition also reduced protein solubility in all protein isolates at pH 6 and in water. Modulation of pH and salt concentration resulted in the tuning of extrudate texture for only one protein source, Yellow Pea UF (ultrafiltration) protein isolate. Higher die pressure and specific mechanical energy was found to correlate with higher extrudate cutting forces. Scanning electron microscopy of the extrudates showed a smooth structure formed by proteins with lower solubility and, in contrast, a more porous structure with the proteins with higher solubility. Notably, Yellow Pea and Faba Bean UF protein isolates with high solubility showed an increase in disordered structures after extrusion. This study demonstrates that plant protein source, pH, and salt addition can be used to modulate extruder response and meat analogue texture.

Memantine is a primary pharmacological treatment for moderate-to-severe Alzheimer's disease but its efficacy and brain delivery remain limited. Lipid bicontinuous cubic phases and their nanoparticle dispersions (cubosomes) offer platforms for enhancing central nervous system drug delivery, yet the rigid adamantane scaffold of memantine can destabilise lipid organisation. This study resolves how an amphiphilic, adamantane-containing drug interacts with non-lamellar lipid bilayers using monoolein-based bulk cubic mesophases and cubosomes formulated with biomimetic lipid compositions and multiple stabilisers. SAXS revealed that lipid composition primarily governed mesophase structure, while memantine induced only modest structural changes in bulk cubic phases. Following memantine incorporation, cubosomes retained cubic symmetry and colloidal stability across stabilisers, although they were more susceptible than bulk phases to additive-induced disorder, with cryo-TEM showing transitions toward less ordered, lower curvature sponge-like structures. Bulk mesophases exhibited 3-5-fold higher apparent drug retention than nanoparticle dispersions. Under excess hydration, however, even bulk phases released memantine rapidly, losing ∼65% of the drug within 24 h. SANS and molecular dynamics simulations revealed a mobile state of memantine with predominantly interfacial localisation rather than stable burial within the hydrophobic tails, providing a mechanistic explanation for its mesophase-dependent structural effects and its limited retention. These findings show that the adamantane scaffold alone is insufficient to ensure efficient incorporation into cubic phases. Localisation, accommodation, and retention are governed by the balance between hydrophobic anchoring and the hydration demands of attached functionalities, establishing a mechanistic framework for predicting the behaviour of amphiphilic adamantane-containing therapeutics in non-lamellar lipid nanocarriers.

Polyhydroxyalkanoates (PHAs) are biopolyesters that accumulate as cytosolic cell inclusions in many bacteria, enhancing resistance to environmental stresses. However, the structure, spatial localization, plasticization effects, and mechanical properties of PHA granules in vivo remain underexplored. Here, Cupriavidus necator H16 grown under nutrient-rich and limited conditions was investigated across a 72 hour accumulation cycle using orthogonal techniques including atomic force microscopy infrared (AFM-IR) spectroscopy, contact resonance mechanical analysis, optical photothermal infrared spectroscopy, nano-thermal analysis, and proteomics to map polyhydroxybutyrate (PHB) granule evolution. Across the PHB production cycle, the PHB content increased from 34 to 69% after 72 hours in minimal media, while in vivo crystallinity reached a maximum of 20% compared to 42-63% when extracted. Ester carbonyl band shifts (1720-1740 cm-1) indicated mostly amorphous PHB in vivo, while contact resonance mapping showed that the granules were mechanically softer than the surrounding cellular matrix. Notably, AFM-IR revealed membrane patterning consistent with spinodal decomposition, representing the first reported observation of spinodal-like membrane organization in C. necator. Proteomics identified increased production of PHB biosynthesis, regulation, and phasin proteins during the stationary phase, supporting phasin-assisted suppression of crystallization. Whole-pathway analysis further revealed stronger perturbations in formate oxidation and polyphosphate metabolism than in PHB biosynthesis alone, highlighting broader metabolic shifts. This study establishes a link between PHB accumulation, crystallinity, mechanical softness, and granule-associated protein production in C. necator, yielding a plasticized intracellular polymer state relevant to flexible bioplastic and biomedical material design.

Plastic waste, particularly polyethylene terephthalate (PET), poses serious environmental threats due to its non-biodegradability and accumulation in ecosystems. Glycolysis depolymerises PET using ethylene glycol (EG) to recover monomers for closed-loop recycling. However, its further adoption is restricted due to EG's high cost and sustainability concerns. Furthermore, water (H2O) carried in the PET feed and added during downstream monomer purification leaves the recovered solvent as an EG/H2O mixture that must be dehydrated before EG reuse. This study reports dual-layer nanocomposite membranes for efficient EG recovery by pervaporation (PV). These membranes consist of a thin, cross-linked polyvinyl alcohol (PVA) selective layer that incorporates solution-processable (SP) nanoparticle forms of covalent organic frameworks (SNW-1), polymeric organic frameworks (POF), hollow silica spheres, and metal-organic frameworks (AlFu and UiO-66-OH) on a polytetrafluoroethylene (PTFE) substrate. This fabrication strategy enables controlled interfacial chemistry between the selective layer and nanoparticles. Surface modification of the nanoparticles improved their solution processability, yielding highly homogeneous membranes with increased hydrophilicity, selectivity, and permeability for EG dehydration. Unlike previous EG dehydration PV studies that mainly focused on EG-rich feeds and higher operating temperatures, this work targets PET-glycolysis-relevant, high-H2O and low-temperature conditions. At 10 wt% loading of SP nanoparticles, the UiO-66-OH-SP-based nanocomposite membrane (PVA-PTFE-UiO-66-OH-SP10 wt%) demonstrated the highest performance, with total flux of 4.40 kg.m(-2).h(-1) and H2O/EG separation factor of 8937 with the same feed composition. This performance significantly surpassed the benchmark PVA-PTFE membrane (H2O/EG separation factor: 160) and exceeded both literature results and the commercial PERVAP (TM) 4101 membrane. These advances not only maximise the recovery efficiency of EG and decrease reliance on virgin EG but also enhance the environmental sustainability and cost-effectiveness of PET recycling. This highlights the potential of PV as an energy-efficient and practically relevant alternative to conventional thermal EG recovery processes by enabling high-purity EG (>99%) recovery. The results demonstrate the promise of SP nanocomposite membranes for sustainable PET recycling within a circular economy framework.

Alternative protein foods with desirable textural properties are of wide interest. Here we investigated the potential to improve pea protein isolate (PPI) gel strength by the addition of pea protein fibrils (PPF). Firstly, optimal conditions for PPF production were investigated, in particular whether the presence of salt (0.15 M NaCl) improved fibril quality when generated under acidic conditions. Pea protein fibrils were prepared in either water (PPFW) or 0.15 M NaCl (PPFS) at pH 2. Fibrils were formed when PPI proteins were hydrolyzed, unfolded, and aggregated into a fibrillar structure as determined by TEM, particle size analysis, CD, and SAXS. AFM-IR confirmed their long, thin morphology and revealed differences in the secondary structures composition of PPFS and PPFW, with high beta-sheet content and increased aggregation observed when adjusted to pH 7. Rheological examination of gels formed from either PPI or PPF individually showed very weak gel strengths at 60 degrees C. Fibrils mixed with PPI at either pH 2 (native fibril-forming condition) or pH 7 (typical for food applications) at a 1:1 ratio formed strong elastic gels. The highest value of the elastic modulus (G' similar to 30 kPa) resulted from PPFS forming a scaffold network for PPI entrapment at pH 2. The viscoelastic material response of all the gels is well described by the Scott Blair model for a critical gel. Analysis of the resulting model parameters indicated a strong and rigid network formed between PPI and PPFS at pH 2, consistent with an open, highly connected network of rigidly bonded flocs. SEM images showed dense interconnected networks with protein aggregates of PPI within a continuous fibrillar matrix. Overall, the incorporation of PPF formed in the presence of salt into PPI gels could significantly enhance the textural properties of pea protein.

Plant-based proteins are gaining attention in the food industry as a healthier and more sustainable alternative to animal proteins due to health concerns, growing global population, water scarcity and climate change. However, controlling their structural and textural characteristics is still a challenge. Combining plant-based proteins with other substances is an effective method for modifying their gelation and textural properties. An enzymatic crosslinking agent, transglutaminase (TG), was herein employed to enhance the gel strength of a mixture consisting of pea protein isolate (PPI) (50 mg/mL) and collagen (3 mg/mL). Rheological oscillatory time sweep analysis showed an enhancement in gel strength of the PPI and collagen gel compared to PPI alone, and even more so after treatment with the cross-linking enzyme. Scanning electron microscopy imaging provided evidence for the formation of gel networks and crosslinks when the protein mixture was treated with low concentrations (2.5 U/mL) of TG, whereas high TG loading (18 U/mL) caused protein phase separation. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis analysis also showed formation of higher molecular weight bands after TG crosslinking. Particle sizes of the PPI and collagen mixture after TG treatment were larger than without TG. In addition, sodium chloride (150 mM) addition significantly improved the gel strength of PPI collagen gels crosslinked by TG. In conclusion, TG with or without salt can be utilized to enhance the strength of PPI and low concentration collagen gels.

The bacterial production of polyhydroxyalkanoates (PHAs), a class of non-toxic, biodegradable, and bio-based polymers, has gained increasing attention as a sustainable alternative to petrochemical plastics. Among PHA producers, Cupriavidus necator H16 and Pseudomonas putida KT2440 are used for their ability to synthesise short- and medium-chain-length PHAs, respectively. While PHAs have been produced from simple hexoses like glucose and fructose, there remains a lack of systematic and integrated analysis linking carbon source, strain selection, monomer composition, and polymer crystallinity to blend behavior in ultrathin films. PHB and mcl-PHA production using Cupriavidus necator H16 and Pseudomonas putida KT2440 on glucose and fructose were compared herein. C. necator accumulated PHB up to 60 wt

Australian native fruits are unique in water-binding and agricultural properties. Optimal preservation for sustainable nutrient delivery is not well understood but essential for increased consumption. Water influences microbial and structural stability, so the anomalous behaviour of water in native fruits requires investigation. Dynamics of hydrocolloid-associated water in the native fruits finger lime, muntrie, riberry, and Kakadu plum, as well as apple, was studied with neutron spectroscopy. Native fruit matrix water featured self-diffusion constants slower than apple by up to 61 %, demonstrating strong monolayer water binding, which was also correlated with drought-tolerance markers. Free water self-diffusion was up to 24 % faster than apple and even 13 % faster than pure water, which in turn was related with diffusion-accelerating minerals e.g. potassium. Stronger water binding in native fruits may be due to more small starch polymers and fewer cellulose polymers. This work advances the sustainable processing of more climate-resilient crops.

Australian native fruits are well-adapted to local climate and have growing interest in their nutritional and sensory qualities. Among the most highly produced are finger limes and muntries. However, published literature on their characterisation and especially their processing is limited. How processing affects the water binding in foods is poorly understood but influences microbial activity and drying behaviour. This work utilised dynamic vapour sorption to study the water binding of apples compared with the native fruits muntries and finger limes, as well as how drying affected this water binding. Unlike in apple, water binding in native fruits was observed to increase after drying. By analysing associated changes to composition, cellular structure and carbohydrate structure, this was correlated to increased breakdown of complex carbohydrates into simple sugars in native fruits. It is suggested this may be a feature of their drought adaptation. Together with a newly proposed equation for the drying heat required, allowing for calculation of the drying heat, these findings can guide more sustainable processing of Australian native fruits as well as other foods.

Nanocomposite films based on TEMPO-mediated oxidized cellulose nanofiber (TOCNF), glycerol as a plasticizer, and lignin nanoparticle (LNP) were fabricated via a simple spray deposition technique to investigate the effect of LNP on the film properties. All films were transparent and flexible, and scanning electron microscopy observation confirmed that the LNPs were integrated into the TOCNF matrix structure. The presence of LNPs endowed the films with UV-shielding capability due to aromatic rings in the structure: Films containing LNPs at 10 wt% achieved 100 % UV-shielding at 378 nm, whereas films without LNPs showed only about 20 % shielding at the same wavelength. LNPs also enhanced surface hydrophobicity, as indicated by an increase in the static water contact angle from 58° to 99°. While LNPs maintained the Young's modulus and tensile strength of the plasticized TOCNF films, they slightly reduced the elongation at break. Water vapor and oxygen barrier performances were decreased by LNP addition, although the amount of LNPs in the film did not clearly affect the properties. Overall, this study demonstrates that bio-based nanocomposite films with excellent UV-shielding properties and improved surface hydrophobicity have the potential to replace conventional petroleum-based packaging materials.

The success of mRNA vaccines for the treatment of COVID-19 has generated enormous interest in mRNA therapeutics for various diseases, highlighting the need for robust delivery platforms. Combining the excellent transfection properties of lipids with the high stability of polymeric nanoparticles in a single hybrid system has become an attractive approach to generate next generation mRNA delivery systems. We introduce a modular lipid-polymer hybrid nanoparticle (LPHNP) design based on medium-chain-length polyhydroxyalkanoates (mcl-PHAs) as sustainable alternative to poly(lactic-co-glycolic acid) (PLGA), and a polymer-lipid (DMG-PEG, or poly(2-ethyl-2-oxazoline-myristic acid (PEtOx-MA)). A small library of LPHNPs containing the cationic lipid DOTAP were synthesized using a scalable microfluidic process. Physico-chemical and biological properties of mRNA-LPHNPs were studied. Results showed that the mcl-PHAs (PHAF10 and PHAGlu) derived from Pseudomonas putida can form distinct LPHNPs depending on polymer-to-lipid ratios, and mcl-PHA composition. Cell toxicity, transfection efficiency, serum stability, and the effect of protein interactions was investigated in HeLa cells and human brain endothelial (hCMEC/D3) cells. Importantly, the particles' biophysical properties and transfection efficacies were not affected after lyophilization and storage at various temperatures for two months. Reporter mRNA was identified across all major organs collected after intravenous injection into mice with limited protein expression in the blood, highlighting the excellent stability of hybrid nanoparticles against blood cell interactions. This approach holds promise for accelerating development of a novel sustainable polymer for mRNA delivery that differs from conventional lipid nanoparticle systems.

Protein gelation can provide texture in plant-based foods and can be influenced by many factors, including protein extraction method and salt addition. However, the protein gelation mechanism is still not well understood for plant proteins, especially for isolates obtained using commercial protein extraction processes. Therefore, the structural changes that legume sources such as yellow pea, faba bean, and soybeans undergo during the gelation process to understand the differences in their gelation mechanisms was investigated herein by using small-angle neutron scattering. Among these protein sources, the commercial extraction method was found to play a major part in the gelation pathway. Intensive protein extraction methods involving isoelectric precipitation led to lower protein solubility (-1-38% w/w), larger insoluble protein particle sizes (60-100 mu m), and a gelation pathway that is dependent on the changes of the insoluble protein particles. In contrast, extraction using ultrafiltration instead of precipitation resulted in higher protein solubility (-18-88% w/w) and smaller insoluble protein particle sizes (40-70 mu m), and the structural changes observed during gelation involved the structural changes of both soluble proteins and insoluble proteins. SEM imaging also showed different gel networks, with fractal networks formed by insoluble proteins (for sources with low solubility) or more homogenous networks formed by the interactions between the soluble proteins (for sources with high solubility). Despite the differences observed in the gelation network and the protein solubility, the gelation strength exhibited by protein sources at low protein solubility were similar to the ones by protein sources at high protein solubility, demonstrating the potential of fractal gel networks in providing texture.

The environmental challenges posed by conventional plastics can be addressed by using bioderived and biodegradable medium-chain-length polyhydroxyalkanoates (mcl-PHAs) produced by Pseudomonas putida KT2440, a microorganism renowned for its versatile biopolymer synthesis capabilities. This study evaluated mcl-PHA production and its properties for packaging and biomedical applications. We investigated the combined use of fatty acids and glucose, which can be derived from food waste, as a sustainable and cost-effective feedstock strategy. Substituting decanoic acid (F10) and dodecanoic acid (F12) with glucose maintains consistent monomer composition, and a 50% glucose substitution in the F12 feedstock boosts the PHA content to 66% in Pseudomonas putida, reducing cell dry weight to 6 g/L while keeping a similar PHA yield of 4 g/L. This approach offers a practical way to reduce costs and maintain polymer quality, boosting its appeal for industrial-scale production. The resulting mcl-PHA was able to form nanostructures via the formation of a nanoemulsion, with sizes between 120 and 350 nm and low dispersity (<0.2). Nanostructure size was influenced by the fatty acid feedstock's chain length, with higher C12 content from F12 producing smaller structures (154 nm), while lower C12 content from F10 resulted in larger structures (207 nm). These nanostructures remained stable for a week under physiological pH but exhibited changes at pH 2, indicating a pH-sensitive platform. This finding opens avenues for developing sustainable, functional biomaterials with potential applications in drug delivery. Overall, this study presents a novel, sustainable approach to high-quality mcl-PHA production. The use of feedstocks that can be derived from food waste and the development of pH-sensitive nanostructures highlight the potential for creating environmentally responsible and functional biomaterials.

The interactions of viral fusion peptides from influenza (E4K and Ac-E4K) and human immunodeficiency virus (gp41 and Ac-gp41) with planar lipid bilayers and monolayers was investigated herein. A combination of surfacesensitive techniques, including quartz crystal microbalance with dissipation (QCM-D), Langmuir-Blodgett areapressure isotherms with Micro-Brewster angle microscopy, and neutron reflectometry, was employed. Differences in the interactions of the viral fusion peptides with lipid bilayers featuring ordered and disordered phases, as well as lipid rafts, were revealed. The HIV fusion peptide (gp41) exhibited strong binding to the DOPC/DOPS bilayer, comprising a liquid disordered phase, with neutron reflectometry (NR) showing interaction with the bilayer's headgroup area. Conversely, negligible binding was observed with lipid bilayers in a liquid ordered phase. Notably, the influenza peptide (E4K) demonstrated slower binding kinetics with DOPC/DOPS bilayers and distinct interactions compared to gp41, as observed through QCM-D. This suggests different mechanisms of interaction with the lipid bilayers: one peptide interacts more within the headgroup region, while the other is more involved in transmembrane interactions. These findings hold implications for understanding viral fusion mechanisms and developing antimicrobials and antivirals targeting membrane interactions. The differential binding behaviours of the viral fusion peptides underscore the importance of considering membrane composition and properties in therapeutic strategy design.

The gelation behaviour of two different pea protein isolates and one soy protein isolate were investigated with a focus on the role of the protein properties. Protein solubility was the lowest in pH 3 citrate-phosphate buffer (<10% w/w), increased in pH 7.4 phosphate-buffered saline (12–21% w/w), and was the highest in pH 7.6 MilliQ water (~20–40% w/w). Heat-induced gelation conditions for the protein sources were sensitive to both the soluble and the insoluble fractions as obtained during extraction. At low protein concentrations (≤5% w/v), the proteins started to lose their viscoelastic behaviour and exhibited predominantly viscous properties. Fitting of the fractional Kelvin-Voigt model to the frequency sweeps showed an increase in the fractal gel strength with increasing protein concentration. Secondary structures of the soluble species showed mostly unordered proteins, suggesting that the proteins were denatured during the commercial extraction process although gelation has to date been suggested to be highly dependent on the denaturation of soluble proteins. Synchrotron Radiation Circular Dichroism measurements of the insoluble proteins showed a significant amount of ordered protein structures. SEM imaging of the gels also suggested a new gelation pathway in which insoluble proteins act as dispersed fillers within a continuous matrix of soluble proteins. The goal of this research is to elucidate the the role of different protein fractions, globulins and albumins, and their secondary structure in the formation of a gel network and how this affects their viscoelastic behaviour.

The partitioning of viral fusion peptides in lipid membranes with varying order was investigated due to the fusion mechanism being a potential therapeutic approach. Using a planar bilayer model and advanced techniques such as neutron reflectometry (NR) and quartz crystal microbalance with dissipation (QCM-D), the structural aspects of peptide-lipid interactions were explored. The study focused on two target membranes: one forming a liquid-ordered domain and the other forming a liquid-disordered domain. Surprisingly, the COVID fusion peptide did not bind significantly to either membrane, as demonstrated by both QCM-D and NR data, suggesting negligible or no interaction with the bilayers. However, the acetylated COVID fusion peptide showed distinct behaviour, indicating a crucial role of N-terminal acetylation in binding to cholesterol-rich liquid-ordered domains. The acetylated peptide induced changes in the structure and thickness of the ordered bilayer with cholesterol whereas proteins and peptides commonly only bind to disordered phases. This study provides valuable insights into the mechanisms of viral membrane fusion and highlights the importance of acetylation in influencing peptide-lipid interactions, laying the groundwork for potential antiviral therapeutic strategies.

Mungbean and lentil proteins are gaining attention for the production of high moisture extrusion (HME)-based meat- and dairy-analogues. However, understanding the mechanism of fibrous structure formation and molecular and higher-order changes in HME remains limited. Globulin protein isolates from mungbean (MBPI), green lentil (GLPI) and yellow pea (YPPI) along with commercial soy (CSPI) and yellow pea (CPPI) protein were investigated for their pasting properties using high-pressure rapid visco analyser (RVA), and the formation of anisotropic structures and molecular changes at constant HME conditions. Vicilin-rich MBPI showed higher viscosity on RVA, consumed higher specific mechanical energy (SME) during extrusion, and developed extrudates with higher textural strength and cutting force than proteins with both legumin and vicilin-like globulins, i.e. GLPI and YPPI. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and size-exclusion chromatography (SEC) of extrudates' soluble proteins showed dissociation of vicilin-like globulins into their smaller subunits. In contrast, legumin-like globulins were reaggregated into higher molecular weight soluble macromolecules. Further, SDS-PAGE of extrudates’ total protein revealed the involvement of legumin-like globulin in the macrostructure network of the extrudates. During HME, native unfolded structures were destroyed with conversion, predominately driving changes in the tertiary structure (thermal denaturation) and secondary structure with loss of helical structure to formation of random coil and beta-sheet structures. Protein extractability in different solvents was greatly reduced, with covalent and non-covalent interactions being majorly involved in the stabilisation of extrudates structure. Protein composition, and in particular vicilin-legumin ratio and protein conformation, determined the structural development and molecular changes in HME.

AbstractCellulose and lignin have been widely studied to develop a bio‐based alternative to replace fossil‐based packaging materials and coatings. Lignin can be used to improve the water vapor barrier properties of cellulose‐based sheets due to its hydrophobicity. In this study, composite sheets based on cellulose nanofiber (CNF) and lignin are formed via spray deposition the effects of lignin particle size and concentration on the properties of the composite sheets are investigated. Scanning electron microscopy and atomic force microscopy with infrared spectroscopy analysis show that lignin nanoparticles (LNPs, particle diameter <100 nm) migrate to the top surface during drying to form a dense layer. The water vapor permeability of the sheet including LNPs is reduced to 4.5 × 10−11 g·s−1·m−1·Pa−1, which is ≈20% lower than the value for CNF alone. This improvement is related to the dense LNP layer on the top surface. Water contact angle measurements indicate that the layer of LNPs also increases the surface hydrophobicity. Overall, this study provides a simple process to produce a fully bio‐based option for packaging material with enhanced water vapor barrier properties and surface hydrophobicity.