Understanding the dissolution of α-zein in aqueous ethanol and acetic acid solutions

Assembly of foxtail millet prolamin/chitosan hydrochloride/carboxymethyl-beta-cyclodextrin in acetic acid aqueous solution for enhanced curcumin retention

The aim of this work is to investigate the assembly of foxtail millet prolamin (FP) with chitosan hydrochloride (CHC) and carboxymethyl-beta-cyclodextrin (CMCD) in acetic acid aqueous solutions. The proportion of acetic acid has a positive impact on the disintegration of FP. With the use of 91.0 % (v/v) acetic acid, FP forms smaller particles of approximately 45 nm (naked FP particles) and 220 nm (FP - CHC - CMCD hybrid particles). In the case of using 61.5 % (v/v) acetic acid, the microstructures of bare FP particles and 570 nm composite FP nanoparticles (NPs) are looser, about 485 nm. Acetic acid inhibits the noncovalent bonds, including the hydrophobic interactions, hydrogen bonding and electrostatic attractions between FP and polysaccharides. Therefore, 3.8 % (v/v) acetic acid can nucleate FP to form more compact FP hybrid particles for delivering curcumin (Cur) with higher encapsulation efficiency, storage stability and release performance, and improve the antibacterial and anticancer activity of Cur.

Zein-based nanostructured coatings: A green approach to enhance virucidal efficacy of protective face masks

Face masks represent a valuable tool to prevent the spreading of airborne viruses; however, they show poor comfort and scarce antiviral efficacy. Zein-based coatings are herein exploited to enhance antiviral performance. Zein functionalization is done through acidifying agents (lactic acid, LA). Coatings are characterized in terms of morphological, mechanical, breathability, and cytotoxicity analyses. The antiviral efficacy is tested in vitro against four viruses (Human Coronavirus OC43, Herpes Simplex Virus type 1, Human Adenovirus type 5, and MPox Virus) according to a biological assay on cell cultures. Zein/Zein LA antiviral activity seems to be linked to its positive surface charge that enables to form electrostatic interactions with negatively charged-viruses, resulting in the highest activity (reduction >2 Log) on Human Coronavirus OC43 and Herpes Simplex Virus type 1, with efficacy comparable or higher than that of copper/copper oxide-based- coatings. No significant activity is observed against Human Adenovirus type 5 and MPox Virus, due to their high resistance to inactivating treatments. Zein-based systems are not cytotoxic and their water vapor permeability is reduced of 26 % compared to that of not-coated systems. These promising results offer interesting insights into design of antiviral and sustainable coatings for personal protective equipment.

Caseinate-coated zein nanoparticles as potential delivery vehicles for guavinoside B from guava: Molecular interactions and encapsulation properties

Guavinoside B (GUB) is a characteristic constituent from guava with strong antioxidant activity; however, its low water solubility limits its utilization. Herein, we investigated the interaction between GUB and zein, a prolamin with self-assembling property, using multiple spectroscopic methods and fabricated GUB-zein-NaCas nanoparticles (GUB-Z-N NPs) via the antisolvent coprecipitation approach. GUB caused fluorescence quenching to zein via the static quenching mechanism. Fourier-transform infrared spectroscopy and computational analysis revealed that GUB bound to zein via van der Waals interaction, hydrogen bond, and hydrophobic forces. The GUB-Z-N NPs were in the nanometric size range (< 200 nm) and exhibited promising encapsulation efficiency and redispersibility after freeze-drying. These particles remained stable for up to 31 days at 4 °C and great resistance to salt and pH variation, and displayed superior antioxidant activity to native GUB. The current study highlights the potential of zein-based nanoparticles as delivery vehicles for GUB in the food industry.

A sustainable zein-based adhesive for various substrates with improved adhesion and stability

Biomass-based adhesives are gaining attention as environmentally friendly alternatives to toxic petroleum-based adhesives. However, biomass-based adhesives exhibit poor adhesive properties and are highly susceptible to failure in humid environments. In this study, a zein-based adhesive with high adhesive strength and good water resistance was prepared by optimizing the solvent composition and adding tannic acid. Adding 10 wt% acetic acid to an aqueous ethanol solvent increased the shear strength by 45.4 % to 3.09 MPa. Moreover, the addition of 6 wt% tannic acid improved the shear strength of the zein-based adhesive in humid environments from 0.63 to 1.58 MPa. The tannic acid-reinforced zein-based adhesive exhibited good adhesive strength in both humid and dry environments, which was maintained for 30 days on glass, and could be applied to a wide range of substrates. Moreover, the adhesive showed an antioxidant activity >94 %, excellent thermal stability, biocompatibility, and antibacterial effect. Therefore, this adhesive has great application prospects in medical, packaging, and other fields.

Lutein encapsulation into dual-layered starch/zein gels using 3D food printing: Improved storage stability and in vitro bioaccessibility

The ability of 3D printing to encapsulate, protect, and enhance lutein bioaccessibility was investigated under various printing conditions. A spiral-cube-shaped geometry was used to investigate the effects of printing parameters, namely zein concentration (Z; 20, 40, and 60 %) and printing speed (PS; 4, 8, 14, and 20 mm/s). Coaxial extrusion 3D printing was used with lutein-loaded zein as the internal flow material, and corn starch paste as the external flow material. The viscosities of the inks, microstructural properties, storage stability, and bioaccessibility of encapsulated lutein were determined. The sample printed with a zein concentration of 40 % at a printing speed of 14 mm/s (Z-40/PS-14) exhibited the best shape integrity. When lutein was entrapped in starch/zein gels (Z-40/PS-14), only 39 % of lutein degraded after 21 days at 25 °C, whereas 78 % degraded at the same time when crude lutein was studied. Similar improvements were also observed after storing at 50 °C for 21 days. Furthermore, after simulated digestion, the bioaccessibility of encapsulated lutein (9.8 %) was substantially higher than that of crude lutein (1.5 %). As a result, the developed delivery system using 3D printing could be an effective strategy for enhancing the chemical stability and bioaccessibility of bioactive compounds (BCs).

Sustainable bioactive food packaging based on electrospun zein-polycaprolactone nanofibers integrated with aster yomena extract loaded halloysite nanotubes

Compostable zein-polycaprolactone (PZ) electrospun nanofiber integrated with different concentrations of Aster yomena extract loaded halloysite nanotubes (A. yomena-HNT) as bioactive nanofibrous food packaging is reported. SEM micrographs reveal heterogeneous nanofibers. A. yomena extract used in the study showed weak antioxidant activity with AAI and TEAC values of 0.229 and 0.346. In vitro, release profile over 7 days of A. yomena indicates a controlled, sustained, and prolonged release. The prepared nanofibers were effective against both gram-positive and gram-negative bacteria. The prepared composite nanofibers were rendered biocompatible and nontoxic when subjected to WST-1 and LDH assay after incubating with NIH 3T3 mouse fibroblast cell line. PZ-15 nanofiber packaging showed the best postharvest quality preservation in Black mulberry fruits after 4 days of storage at 25 °C and 85 % Rh. Moreover, the in vitro decomposition test reveals that the fabricated nanofibers decompose in the soil and do not pose as a threat to the environment.

Impacts of ethanol-plasticization and extrusion on development of zein network and structure of zein-starch dough

To improve the viscoelasticity of zein in gluten-free dough, ethanol-plasticization and extrusion modification were employed. The peak viscosity of UZS (unextruded zein-starch) flour and EZS (extruded zein-starch) flour with ethanol (10 %, v/v) increased from 1340.0 to 1996.5 mPa·s and 1336.3 to 2291.5 mPa·s, and the bound bromophenol blue increased from 7.1 μg to 10.6 μg and 5.3 μg to 5.9 μg, respectively. Ethanol-plasticization enhanced zein's hydrophobic interactions and promoted zein network development, thus improving dough compatibility. However, the dense structure of the extruded zein made ethanol inaccessible to the interior, and the structural improvement on extruded zein-starch dough was limited. A model was developed to explain the influences of extrusion and ethanol-plasticization on the behavior of zein in the dough. Extrusion reduces the fiber-forming ability of zein, while ethanol-plasticization facilitates extensive fibrous network formation. This study provides a sound basis for the development of zein in gluten-free foods.

Short-Stranded Zein Fibers for Muscle Tissue Engineering in Alginate-Based Composite Hydrogels

Cultivated meat is a nascent technology that aims to create an environmentally and animal-friendly alternative to conventional meat. Producing skeletal muscle tissue in an animal-free system allowing for high levels of myofusion and maturation is important for the nutritional and sensorial value of cultivated meat. Alginate is an attractive biomaterial to support muscle formation as it is food-safe, sustainable and cheap and can be crosslinked using non-toxic methods. Although alginate can be functionalized to promote cell attachment, limitations in its mechanical properties, including form, viscosity, and stress relaxation, hinder the cellular capacity for myogenic differentiation and maturation in alginate-based hydrogels. Here, we show that the addition of electrospun short-stranded zein fibers increased hydrogel degradation, resulting in faster compaction, improved cell-gel interaction, and enhanced alignment of bovine muscle precursor cells. We conclude that fiber-hydrogel composites are a promising approach to support optimal formation of 3D constructs, by improving tissue stability and thus prolonging culture duration. Together, this improves muscle-related protein content by facilitating myogenic differentiation and priming muscle organoids for maturation.

Porous Thermoformed Protein Bioblends as Degradable Absorbent Alternatives in Sanitary Materials

Protein-based porous absorbent structures can be processed and assembled into configurations suitable for single-use, biodegradable sanitary materials. In this work, a formulation based on a mixture of proteins available as industrial coproducts is processed into continuous porous structures using extrusion and assembled using conventional thermal methods. The experimental design led to formulations solely based on zein-gluten protein bioblends that could be manufactured as liquid absorbent pellets, compressed pads, and/or porous films. The processing versatility is attributed to the synergistic effect of zein as a low viscosity thermoformable protein with gluten as a readily cross-linkable high molecular weight protein. The capillary-driven sorption, the biodegradability of the materials, and the possibility to assemble the products as multilayer components provide excellent performance indicators for their use as microplastic-free absorbents. This work shows the potential of biopolymers for manufacturing sustainable alternatives to current nonbiodegradable and highly polluting disposable items such as pads and diapers.

Succinylation of zein and gelatin hydrolysates improved their ice recrystallization inhibition activity

The goal of this research was to enhance the ice recrystallization inhibition (IRI) activity of zein and gelatin hydrolysates (ZH and GH, respectively) by succinylation modification. ZH was prepared by Alcalase treatment for 3 h and then modified by succinic anhydride (SA); whereas GH was made by Alcalase hydrolysis for 0.25 h and succinylated by n-octylsuccinic anhydride (OSA). After 0.5 h of annealing at -8 °C at 40 mg/mL, modified hydrolysates decreased the average Feret's diameter of ice crystal from 50.2 μm (polyethylene glycol, negative control) to 28.8 μm (SA modified ZH) and 29.5 μm (OSA modified GH) in comparison to the unmodified hydrolysates, which had the crystal size of 47.2 μm (ZH) and 45.4 μm (GH). Also, the two succinylated samples had altered surface hydrophobicity, which potentially contributed to their enhanced IRI activity. Our results indicate that succinylation of food-derived protein hydrolysates can improve their IRI activity.

Iron-Containing Protein-Mimic Supramolecular Iron Delivery Systems for Ferroptosis Tumor Therapy

Ferroptosis provides an innovative theoretical basis and method for tumor therapy but is limited by the low efficiency of conventional iron delivery systems. Herein, an efficient supramolecular iron delivery system (SIDS) is demonstrated upon the hydrolysis of FeCl₃, condensation of amino acids, and self-assembly of iron-containing components. The as-assembled SIDS possesses a shuttle-like core/shell structure with β-FeOOH as the core and Fe³⁺/polyamino acid coordinated networks as shells. The iron content of SIDS is up to 42 wt %, which is greatly higher than that of ferritin. The iron-containing protein-mimic structure and shuttle-like morphology of SIDS facilitate tumor accumulation and cell internalization. Once exposed to the tumor microenvironment with overexpressed glutathione (GSH), the SIDS will disassemble, accompanied by the depletion of GSH and the release of Fe²⁺, leading to dual amplified ferroptosis. Primary studies indicate that SIDS exhibits outstanding antitumor efficacy on bladder cancer.

Hierarchically Porous Films Architectured by Self-Assembly of Prolamins at the Air-Liquid Interface

Artificial recapitulation of hierarchically porous films gained great interest due to their versatile functionalities and applications. However, the development of novel eco-friendly and nontoxic biopolymer-based porous films is still limited by the time-consuming fabrication processes and toxic organic reagents involved. Here, we reported a novel approach to rapidly (within 5 s) fabricate biopolymer-based hierarchically porous films via inducing the laterally occurring interfacial self-assembly of prolamins at the air-liquid interface during an antisolvent dripping procedure. The as-prepared films exhibited a hierarchically porous microstructure (with sizes of about 500 nm to 5 μm) with location-graded and Janus features. The formation mechanism involved the solvent gradient controlled self-assembly of prolamin into an anisotropic defect structure in longitudinal and lateral directions. Accordingly, the macroscopic morphologies together with the porosity and pore size could be precisely tuned by solvents and operating parameters in a convenient way. Furthermore, alcohol-soluble but water-insoluble bioactive compounds could be incorporated simultaneously via a one-step loading procedure, which endowed films with large loading efficiency and sustained release features suitable for controlled release applications. The effect of the curcumin-loaded porous film on skin wound healing, as one of the potential applications of this novel material, was then investigated in vivo in a full-thickness wound model, wherein satisfying wound healing effects were achieved through multitarget and multipathway mechanisms. This pioneering work offers a novel strategy for the rapid architecture of biopolymer-based hierarchically porous film with versatile application potentials.

Zein-based nano-delivery systems for encapsulation and protection of hydrophobic bioactives: A review

Zein is a kind of excellent carrier materials to construct nano-sized delivery systems for hydrophobic bioactives, owing to its unique interfacial behavior, such as self-assembly and packing into nanoparticles. In this article, the chemical basis and preparation methods of zein nanoparticles are firstly reviewed, including chemical crosslinking, emulsification/solvent evaporation, antisolvent, pH-driven method, etc., as well as the pros and cons of different preparation methods. Various strategies to improve their physicochemical properties are then summarized. Lastly, the encapsulation and protection effects of zein-based nano-sized delivery systems (e.g., nanoparticles, nanofibers, nanomicelles and nanogels) are discussed, using curcumin as a model bioactive ingredient. This review will provide guidance for the in-depth development of hydrophobic bioactives formulations and improve the application value of zein in the food industry.

Explore the Interaction between Ellagic Acid and Zein Using Multi-Spectroscopy Analysis and Molecular Docking

With the increasing interest in value-added maize products, the interaction of zein with bioactive molecules to become more nutritional and beneficial to human health has gained a lot of attention. To broaden the application of ellagic acid (EA) in maize flour products, we investigated the interaction between zein and EA. The fluorescence quenching type of zein interacting with EA was mainly static quenching through hydrophobic interaction, as demonstrated by quenching behavior modeling, and ultraviolet-visible spectroscopy confirmed the formation of zein–EA complexes. Synchronous fluorescence spectroscopy showed that EA reduced the polarity of zein around tyrosine residues, which were exposed to a more hydrophobic microenvironment. Meanwhile, circular dichroism suggested that EA noticeably changed the secondary structure of zein, which was mainly reflected in the increase of α-helix and β-sheet content and the decrease of random coil content. Finally, the molecular docking simulation found that zein could have five active sites binding to EA and there was hydrogen bond interaction besides hydrophobic interaction. The findings of this study provided a basis for a theory for the interaction mechanism between zein and EA, which could be essential for developing value-added plant-derived protein products using EA as a functional component.

Development of a Method for Fast Assessment of Protein Solubility Based on Ultrasonic Dispersion and Differential Centrifugation Technology

Protein solubility is very important for protein crystallization, bioprocess development, and protein application. In this study, a method based on the stability of a protein dispersion system is proposed for fast assessment of protein solubility, which mainly involves ultrasonic dispersion, differential centrifugation, and spectral measurement (UDDCS) and curvature estimation. The appropriate ultrasonic time and centrifugal time were experimentally determined at first. The results show that the relationship between the standard deviation and the protein concentrations originally added accords with the modified exponential equation, and the corresponding concentration of the maximum curvature point is defined as the solubility of the protein. Lysozyme solubility data in NaCl aqueous solutions and zein solubility data in ethanol aqueous solutions are selected to verify the UDDCS method by comparing the data obtained by the UDDCS method and the results from references, and the results indicate that the UDDCS method is reliable, universal, and time-saving. Finally, measurements of zein solubility in NaOH solution and casein solubility in urea aqueous solution were conducted as test cases by the UDDCS method.

Modification of zein dough functionality using kafirin as a coprotein

Kafirin, sorghum prolamin, was investigated as a coprotein for zein as visco-elastic masses and in starch-based model doughs. Regular kafirin and kafirins from waxy and high protein digestibility (HD) sorghum crosses were studied. HPLC revealed that waxy-HD kafirin was of smaller molecular size and low in β-kafirin. It also had greater surface hydrophobicity. Kafirin addition to zein increased visco-elastic mass elasticity up to ≈50% stress-recovery, similar to wheat gluten. Waxy-HD kafirin gave the highest elasticity, possibly due to its hydrophobicity. Kafirin inclusion at 2:8 parts zein increased the tensile strength of model doughs. Maximum strength was, however, only 60% that of gluten-based dough. Kafirin from regular sorghum gave the highest strength, possibly because of greater disulphide-bonded polymerisation. Confocal laser scanning microscopy showed that zein-kafirin copolymers formed fairly linear fibrils in stretched doughs, indicating excellent compatibility between the proteins. Future research should establish how kafirin-zein copolymer performs in non-wheat flour products.

Reducing synthetic colorants release from alginate-based liquid-core beads with a zein shell

An innovative method to reduce hydrophilic synthetic colorant release at interface was presented in this work, based on the anti-solvent effect at the membrane outside surface of liquid-core beads manufactured by reverse spherification between alginate and calcium ion. Zein, a hydrophobic protein which formed precipitation shell ensured the stability of colorant. Acidification of solvent made zein particles more kinetically stable, allowed zein stretching and collated more orderly secondary structures even in high polarity solvents. Colorants that hydrogen bonded or electrostatically interacted with zein could have optimized release properties. The zein/erythrosine samples had the most orderly secondary structure from circular dichroism and had the highest stability among all zein/colorant systems. The release rate of erythrosine was only 2.76% after 48 h storage after soaking in zein shell solution. This study demonstrated a promising clean and scalable strategy to encapsulate hydrophilic compounds in zein-based shells of liquid-core beads for food, supplement and pharmaceutical applications.

Enhancing Intestinal Permeability of Theaflavin-3,3'-digallate by Chitosan-Caseinophosphopeptides Nanocomplexes

Low intestinal permeability is an unfavorable feature that limits the bioavailability of many hydrophilic polyphenols. In this study, chitosan (CS) was used to complex with caseinophosphopeptides (CPPs), aiming to improve the intestinal permeability of theaflavin-3,3'-digallate (TF-3), a characteristic polyphenol in black tea with poor intestinal permeability. Complexation between CS and CPPs was systemically investigated by turbidimetric titration under various conditions, revealing that electrostatic interaction was the dominant force. The sizes, PDIs, and ζ potentials of CS-CPP nanocomplexes varied with their compositions. The optimized CS-CPP nanocomplex was subsequently used to encapsulate TF-3, which showed high encapsulation efficiency and low cytotoxicity. Microstructural studies showed strong intermolecular associations between CS, CPPs, and TF-3. Encapsulation of TF-3 maintained the globular unit structure of CS-CPP nanocomplexes, but high concentrations of TF-3 resulted in aggregation. Importantly, as proved using the Caco-2 monolayer model, the intestinal permeability of TF-3 was significantly enhanced by the CS-CPP nanocomplexes.

Plant protein-based fibers: Fabrication, characterization, and potential food applications

Proteins from plants have been considered as safer, healthier, and more sustainable resources than their animal counterparts. However, incomplete amino acid composition and relatively poor functionality limit their applications in foods. Structuring plant proteins to fibrous architectures enhances their physicochemical properties, which can favor various food applications. This review primarily focuses on fabrication of fibers from plant proteins via self-assembly, electrospinning, solution blow spinning, wet spinning, and high-temperature shear, as well as on several applications where such fibrous proteins assemble in quality foods. The changes of protein structure and protein-protein interactions during fiber production are discussed in detail, along with the effects of fabrication conditions and protein sources on the morphology and function of the fibers. Self-assembly requires proteolysis and subsequent peptide aggregation under specific conditions, which can be influenced by pH, salt and protein type. The spinning strategy is more scalable and produces uniformed fibers with larger length scales suitable for encapsulation, food packaging and sensor substrates. Significant progress has been made on high-temperature shear (including extrusion)-induced fibers responsible for desirable texture in meat analogues. Structuring plant proteins adds values for broadened food applications, but it remains challenging to keep processes cost-effective and environmentally friendly using food grade solvents.

Controlled self-assembly of plant proteins into high-performance multifunctional nanostructured films

The abundance of plant-derived proteins, as well as their biodegradability and low environmental impact make them attractive polymeric feedstocks for next-generation functional materials to replace current petroleum-based systems. However, efforts to generate functional materials from plant-based proteins in a scalable manner have been hampered by the lack of efficient methods to induce and control their micro and nanoscale structure, key requirements for achieving advantageous material properties and tailoring their functionality. Here, we demonstrate a scalable approach for generating mechanically robust plant-based films on a metre-scale through controlled nanometre-scale self-assembly of water-insoluble plant proteins. The films produced using this method exhibit high optical transmittance, as well as robust mechanical properties comparable to engineering plastics. Furthermore, we demonstrate the ability to impart nano- and microscale patterning into such films through templating, leading to the formation of hydrophobic surfaces as well as structural colour by controlling the size of the patterned features.

Towards the Enhancement of Essential Oil Components' Antimicrobial Activity Using New Zein Protein-Gated Mesoporous Silica Microdevices

The development of new food preservatives is essential to prevent foodborne outbreaks or food spoilage due to microbial growth, enzymatic activity or oxidation. Furthermore, new compounds that substitute the commonly used synthetic food preservatives are needed to stifle the rising problem of microbial resistance. In this scenario, we report herein, as far as we know, for the first time the use of the zein protein as a gating moiety and its application for the controlled release of essential oil components (EOCs). The design of microdevices consist of mesoporous silica particles loaded with essential oils components (thymol, carvacrol and cinnamaldehyde) and functionalized with the zein (prolamin) protein found in corn as a molecular gate. The zein protein grafted on the synthesized microdevices is degraded by the proteolytic action of bacterial enzymatic secretions with the consequent release of the loaded essential oil components efficiently inhibiting bacterial growth. The results allow us to conclude that the new microdevice presented here loaded with the essential oil component cinnamaldehyde improved the antimicrobial properties of the free compound by decreasing volatility and increasing local concentration.

The Effect of Electrophoretic Deposition Parameters on the Microstructure and Adhesion of Zein Coatings to Titanium Substrates

Zein coatings were obtained by electrophoretic deposition (EPD) on commercially pure titanium substrates in an as-received state and after various chemical treatments. The properties of the zein solution, zeta potential and conductivity, at varying pH values were investigated. It was found that the zein content and the ratio of water to ethanol of the solution used for EPD, as well as the process voltage value and time, significantly influence the morphology of coatings. The deposits obtained from the solution containing 150 g/L and 200 g/L of zein and 10 vol % of water and 90 vol % of ethanol, about 4-5 μm thick, were dense and homogeneous. The effect of chemical treatment of the Ti substrate surface prior to EPD on coating adhesion to the substrate was determined. The coatings showed the highest adhesion to the as-received and anodized substrates due to the presence of a thick TiO2 layer on their surfaces and the presence of specific surface features. Coated titanium substrates showed slightly lower electrochemical corrosion resistance than the uncoated one in Ringer's solution. The coatings showed a well-developed surface topography compared to the as-received substrate, and they demonstrated hydrophilic nature. The present results provide new insights for the further development of zein-based composite coatings for biomedical engineering applications.

Incorporation of Plasticizers and Co-proteins in Zein Electrospun Fibers

As a means to alter the physical properties of electrospun zein fibers, plasticizers (glycerol, lactic acid, and oleic acid) or co-proteins (casein, whey protein, rice protein) were mixed with zein using the solvents acetic acid or aqueous ethanol with or without sodium hydroxide. Incorporating plasticizers or co-proteins had a negligible impact on solution viscosity, solution surface tension, and fiber formation, although electron microscopy of fiber mats showed an increase in bead formation with added co-proteins. Gel electrophoresis identified casein and whey protein in spun mats. Infrared spectra demonstrated the inclusion of plasticizers in fiber mats. Glycerol, lactic acid, and oleic acid reduced the glass transition temperature of bulk fibers. Nanoindentation tests of individual fibers found reduced Young's moduli with added lactic or oleic acids but increased moduli with added casein. Thus, electrospinning zein with food-grade plasticizers or proteins physically modifies fibers, yet incorporating significant protein quantities remains a challenge.

Air-jet spinning corn zein protein nanofibers for drug delivery: Effect of biomaterial structure and shape on release properties

Nanofiber materials are commonly used as delivery vehicles for dermatological drugs due to their high surface-area-to-volume ratio, porosity, flexibility, and reproducibility. In this study air-jet spinning was used as a novel and economic method to fabricate corn zein nanofiber meshes with model drugs of varying solubility, molecular weight and charge. The release profiles of these drugs were compared to their release from corn zein films to elucidate the effect of geometry and structure on drug delivery kinetics. In film samples, over 50% of drug was released after only 2 h. However, fiber samples exhibited more sustained release, releasing less than 50% after one day. FTIR, SEM, and DSC were performed on nanofibers and films before and after release of the drugs. Structural analysis revealed that the incorporation of model drugs into the fibers would transform the zein proteins from a random coil network to a more alpha helical structure. Upon release, the protein fiber reverted to its original random coil network. In addition, thermal analysis indicated that fibers can protect the drug molecules in high temperature above 160 °C, while drugs within films will degrade below 130 °C. These findings can likely be attributed to the mechanical infiltration of the drug molecules into the ordered structure of the zein fibers during their solution fabrication. The slow release from fiber samples can be attributed to this biophysical interaction, illustrating that release is dictated by more than diffusion in protein-based carriers. The controlled release of a wide variety of drugs from the air-jet spun corn zein nanofiber meshes demonstrates their success as drug delivery vehicles that can potentially be incorporated into different biological materials in the future.

Formation and Characterization of Zein-Based Oleogels

Oleogels are interesting as a result of their ability to hold large amounts of oil in a semi-solid gel structure. In the food industry, oleogels are most often investigated as substitutes for saturated and trans fats. In this work, the lyotropic formation of ethanol/zein/oleic acid gels was observed qualitatively and ternary phase diagrams were constructed to map the observations. The viscoelastic parameters G' and G'' were measured to confirm gel formation as observed in phase diagrams. Ultrasmall X-ray scattering was used to study the microstructural organization of ethanol/zein/oleic acid gels. Data suggested that the primary unit or building block for gel network structures was the rod-shaped zein molecule. Ultrasmall X-ray data suggested that zein/oleic acid gels have a highly organized microstructure, possibly the result of zein self-assembly. Zein was considered an effective oleogelator in ethanol/zein/oleic acid systems.

Corn Oil-Water Separation: Interactions of Proteins and Surfactants at Corn Oil/Water Interfaces

Purification and collection of industrial products from oil-water mixtures are commonly implemented processes. However, the efficiencies of such processes can be severely influenced by the presence of emulsifiers that induce the formation of small oil droplets dispersed in the mixtures. Understanding of this emulsifying effect and its counteractions which occur at the oil/water interface is therefore necessary for the improvement of designs of these processes. In this paper, we investigated the interfacial mechanisms of protein-induced emulsification and the opposing surfactant-induced demulsification related to corn oil refinement. At corn oil/water interfaces, the pH-dependent emulsifying function of zein protein, which is the major storage protein of corn, was elucidated by the surface/interface-sensitive sum frequency generation (SFG) vibrational spectroscopy technique. The effective stabilization of corn oil droplets by zein protein was illustrated and correlated to its ordered amide I group at the oil/water interface. Substantial decrease of this ordering with the addition of three industrial surfactants to corn oil-zein solution mixtures was also observed using SFG, which explains the surfactant-induced destabilization and coalescence of small oil droplets. Surfactant-protein interaction was then demonstrated to be the driving force for the disordering of interfacial proteins, either by disrupting protein layers or partially excluding protein molecules from the interface. The ordered zein proteins at the interface were therefore revealed to be the critical factor for the formation of corn oil-water emulsion.

Encapsulation Using Plant Proteins: Thermodynamics and Kinetics of Wetting for Simple Zein Coacervates

Traditionally, complex coacervates of oppositely charged biopolymers have been used to form coatings around oil droplets for encapsulation of oil-soluble payloads. However, many proteins can form coacervates by themselves under certain conditions. Here, we revisit the well-known simple coacervates of prolamins such as zein in mixed solvents to explore whether they can be used for plant-based encapsulation systems. We show that, for zein in mixed water/propylene glycol (PG) solvents, we can encapsulate limonene droplets but only under specific conditions. We illustrate that this limitation is due to the very different physical properties of the simple zein coacervates as compared to those of the more extensively studied complex coacervates. Droplets of simple coacervates of zein can carry a significant net charge, whereas complex coacervates are usually close to being charge-balanced. In particular, we demonstrate that the spreading of zein coacervates at the interface of the droplets is thermodynamically favorable due to their extremely low interfacial tensions in both the dispersed (∼0.24 mN/m) and oil phases (∼0.68 mN/m), but the kinetics of coacervate droplet deposition and the interactions among coacervate droplets that oppose coacervate droplet coalescence are highly pH-dependent, leading to a sharp pH optimum (around pH 8) for capsule formation.

Electrospun Polymer Nanofiber from Moringa Oleifera Kernel Oil with Coaxial Electrospinning Method

Background:

Moringa oleifera kernel oil consist of monounsaturated fatty acid with high percentage of oleic acid. The oil consist of phytochemicals, bioactive compounds and nutrients that have several application in health industries. However, the oil degrades on exposure to light, heat and oxygen overtime. In addition, rancidity cause the oil quality to defect and reduce the shelf-life. Therefore, microencapsulation techniques are uniquely applied to oil to preserve their native quality and prolong their shelf life.

Objective:

This study examines different polymer concentrations and injection flowrates of zein nanofiber from Moringa oleifera kernel oil using coaxial electrospinning method.

Methods:

A 40% w/v zein polymer was the optimal loading concentration and 0.7 mL/hour of zein polymer with 0.1 mL/hour of Moringa oleifera kernel oil was the optimal injection flowrates for electrospun nanofiber. Analysis of the Moringa oleifera kernel oil and polymer sample micromorphology, were investigated with Field Emission Scanning Electron Microscopy (FESEM) and transmission electron microscopy (TEM).

Result:

result shows uniformly layered nanofiber. The nanofiber has no beads formation and the fiber strands are continuous with no entanglement. The polymer encapsulated the oil efficiently. Furthermore, thermal analysis through Differential Scanning Calorimetry (DSC) showed consistency in the nanofiber thermal behavior. Thermogravimetric (TGA) analysis revealed the weight loss and thermal dissociation of the polymer structure. The electrospun nanofiber average diameter was 450 ± 24 nm and exhibited hydrophobicity.

Conclusion:

The co-axial electrospine technique was effective in fabricating electrospune nanofibers.