Fast-dissolving antioxidant nanofibers based on Spirulina protein concentrate and gelatin developed using needleless electrospinning

A novel gelatin/chitosan-based "sandwich" antibacterial nanofiber film loaded with perillaldehyde for the preservation of chilled chicken

Quality deterioration caused by microorganisms is a crucial problem in food industry. Herein, to enhance the antibacterial effect and extend the storage life of chilled chicken, a gelatin/chitosan (GC)-based "sandwich" nanofiber film was prepared by sandwiching GP2 (gelatin nanofibers loaded with 2 % (v/v) perillaldehyde) between two layers of GC nanofibers. The diameter of GP nanofibers was positively correlated with perillaldehyde concentration. However, the thermal stability of GP nanofibers was negatively correlated. The thermal degradation temperature (Tm) of GP2 was the lowest. Fortunately, GC nanofibers improved Tm of GP2 from 98.91 °C to 111.60 °C. Besides, FTIR absorption bands at 1636 and 1442 cm-1 indicated that perillaldehyde was successfully embedded. Moreover, poor water resistance of gelatin nanofibers was also improved. Specifically, benefiting from the synergy between perillaldehyde and chitosan, the shelf-life of chilled chicken was efficiently prolonged (over 10 days). Thus, this "sandwich" nanofiber film shows promise for food packaging.

Novel functional carriers based on Spirulina protein for the delivery of curcumin with improved stability and antioxidant efficiency

The potential of sustainably sourced Spirulina protein (SP), and SP nanoparticles (SPNP) obtained by heating gelation and ultrasound treatment as functional carriers for curcumin (Cur) was studied. The antioxidant activity, encapsulation performance, stability and digestive properties of the delivery system were analyzed. Compared with SP, SPNP exhibited higher hydrophobicity, and its antioxidant capacity was enhanced due to increased exposure of chromophores. The encapsulation performance of Cur-loaded complexes was influenced by the protein-Cur mass ratio, and the encapsulation efficiency of SPNP was significantly higher than that of SP (p < 0.05). Because of the better binding affinity, SPNP-Cur complexes showed improved thermal stability and UV protection effect. SP and SPNP all exhibited antioxidant synergism with Cur, and the antioxidant efficiency was closely related to pH, dissociating solvents, UV irradiation and digestion. The bioaccessibility of Cur was also greatly improved. It suggests that Spirulina protein may be an ideal carrier for delivering nutraceutical compounds.

Recent trends in edible algae functional proteins: Production, bio-functional properties, and sustainable food packaging applications

In recent years, there has been a notable surge in the development and adoption of edible algae protein-based sustainable food packaging, which presents a promising alternative to traditional materials due to its biodegradability, renewability, and minimal environmental impact. Hence, this review aims to emphasize the sources, cultivation, and downstream potential of algal protein and protein complexes. Moreover, it comprehensively examines the advancements in utilizing protein complexes for smart and active packaging applications, while also addressing the challenges that must be overcome for the widespread commercial adoption of algal proteins to meet industry 4.0. The review revealed that the diversity of algae species and their sustainable cultivation methods offers a promising alternative to traditional protein sources. Being vegan source with higher photosynthetic conversion efficiency and reduced growth cycle has permitted the proposition of algae as proteins of the future. The unique combination of techno-functional combined with bio-functional properties such as antioxidant, anti-inflammatory and antimicrobial response have captured the sustainable groups to invest considerable research and promote the innovations in algal proteins. Food packaging research has increasingly benefited by the excellent gas barrier property and superior mechanical strength of algal proteins either stand alone or in synergy with other biodegradable polymers. Advanced packaging functionality such as freshness monitoring and active preservation techniques has been explored and needs considerable characterization for commercial advancement. Overall, while algal proteins show promising downstream potential in various industries aligned with Industry 4.0 principles, their broader adoption hinges on overcoming these barriers through continued innovation and strategic development.

Response surface optimization of protein extraction from cold-pressed terebinth (Pistacia terebinthus L.) oil byproducts: Physicochemical and functional characteristics

The current study focused on optimizing the extraction parameters of terebinth seed proteins from cold-pressed terebinth oil byproducts to maximize protein purity and protein yield. The isolated proteins were characterized to evaluate their properties; thus revealing the valorization potential of these byproducts. Response surface methodology was used to detect the effect of three extraction parameters (pH, temperature, and time). The protein isolates were studied for their physicochemical and functional characteristics. The results indicated that an extraction pH of 8, a temperature of 50°C, and an extraction period of 60 min are optimum conditions for obtaining protein isolates with the highest purity. On the other hand, it was demonstrated that an extraction pH of 12, a temperature of 46.4°C, and an extraction duration of 102.4 min were optimum conditions for the maximum protein yield. The proteins produced under these two sets of conditions, referred to as TRP (terebinth protein with maximum purity) and TRY (terebinth protein with maximum yield), respectively, exhibited comparable oil absorption capacity (OAC), foaming, emulsifying capabilities, and stability. Both proteins showed the highest solubility at pH 11, and their zeta potentials approached zero at pH 4, indicating proximity to their isoelectric points. However, FRAP and DPPH assays showed that TRP and TRY offered low antioxidative capacity. The high β-sheet content in TRP and TRY suggests enhanced thermal stability but reduced digestibility of these proteins. Therefore, in addition to protein enrichment, TRP and TRY protein isolates can be utilized in muffins and other food applications thanks to their favorable oil absorption, foaming and emulsifying capacities, and thermal stabilities.

Electrospun gelatin/tea polyphenol@pullulan nanofibers for fast-dissolving antibacterial and antioxidant applications

Bio-based active food packaging materials have a high market demand. We use coaxial electrospinning technology to prepare core-shell structured nanofibers with sustained antibacterial and antioxidant properties. The fiber core layer was composed of gelatin and tea polyphenols, whereas tea polyphenols provide antibacterial and antioxidant properties; the fiber sheath was composed of pullulan polysaccharides with antioxidant properties. By using a scanning electron microscope, it can be seen that the diameter distribution of the prepared nanofibers was uniform and the surface is smooth; using a transmission electron microscope, it can be clearly seen that the nanofibers have a core-shell structure; Fourier Transform Infrared and X-ray diffraction analysis indicate that the nanofibers have an amorphous structure; the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging shows that nanofibers have higher antioxidant properties with the addition of tea polyphenols; antibacterial test showed that nanofibers had obvious inhibitory effect on the growth of Staphylococcus aureus and Escherichia coli; and the nanofiber film dissolution test shows that nanofibers can be used as fast soluble active packaging. Finally, core-sheath-structured nanofibers can serve as active packaging for instant food, possessing both rapid water solubility and excellent antibacterial and antioxidant activity, making water-soluble nanofibers interesting applications in the field of food packaging.

Electrospun nanofibers incorporating lactobionic acid as novel active packaging materials: biological activities and toxicological evaluation

In this study, lactobionic acid (LBA) was incorporated into poly(vinyl alcohol) (PVA) and poly(ε-caprolactone) (PCL) by electrospinning. The antimicrobial effects of the nanofibers were tested using the agar diffusion method. Only the PVA formulations showed antimicrobial activity against Staphylococcus aureus. The PVA and PCL nanofibers containing LBA showed antioxidant activity ranging from 690.33 to 798.67 µM TEAC when tested by the ABTS method. The characterization of nanofibers was performed by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and mechanical analysis. The nanofibers showed a uniform morphology and their average diameters ranged from 295.5 to 2778.2 nm. The LBA addition induced a decrease in the enthalpy of fusion (ΔHm) of PVA and PCL nanofibers, while the Young's modulus was reduced from 20 to 10 MPa in PCL and PCL-LBA nanofibers, respectively. No relevant differences were observed between the FTIR spectra of the control nanofibers and the nanofibers containing LBA. All nanofibers presented hemolysis rate below 2%, thus can be considered as non-hemolytic materials. Further toxicological assessment was performed with the selected formulation PVA10 + LBA. The evaluations by mutagenicity assay, cell survival measurement, cell viability analysis and agar diffusion cytotoxicity test indicated that there are no significant toxic effects. Electrospun nanofibers PVA-LBA and PCL-LBA were successfully produced, showing good thermal and mechanical properties and non-toxic effects. Furthermore, the nanofibers showed antimicrobial activity and antioxidant activity. The findings of this study indicate that PVA and PCL electrospun nanofibers incorporating LBA are promising for use in packaging applications.

Electrospun Poly-ε-Caprolactone Nanofibers Incorporating Keratin Hydrolysates as Innovative Antioxidant Scaffolds

This manuscript describes the development and characterization of electrospun nanofibers incorporating bioactive hydrolysates obtained from the microbial bioconversion of feathers, a highly available agro-industrial byproduct. The electrospun nanofibers were characterized using different instrumental methods, and their antioxidant properties and toxicological potential were evaluated. Keratin hydrolysates (KHs) produced by Bacillus velezensis P45 were incorporated at 1, 2.5, and 5% (w/w) into poly-ε-caprolactone (PCL; 10 and 15%, w/v solutions) before electrospinning. The obtained nanofibers were between 296 and 363 nm in diameter, showing a string-like morphology and adequate structural continuity. Thermogravimetric analysis showed three weight loss events, with 5% of the mass lost up to 330 °C and 90% from 350 to 450 °C. Infrared spectroscopy showed typical peaks of PCL and amide bands corresponding to keratin peptides. The biological activity was preserved after electrospinning and the hemolytic activity was below 1% as expected for biocompatible materials. In addition, the antioxidant capacity released from the nanofibers was confirmed by DPPH and ABTS radical scavenging activities. The DPPH scavenging activity observed for the nanofibers was greater than 30% after 24 h of incubation, ranging from 845 to 1080 µM TEAC (Trolox equivalent antioxidant capacity). The antioxidant activity for the ABTS radical assay was 44.19, 49.61, and 56.21% (corresponding to 972.0, 1153.3, and 1228.7 µM TEAC) for nanofibers made using 15% PCL with 1, 2.5, and 5% KH, respectively. These nanostructures may represent interesting antioxidant biocompatible materials for various pharmaceutical applications, including wound dressings, topical drug delivery, cosmetics, and packaging.

The Application of Protein Concentrate Obtained from Green Leaf Biomass in Structuring Nanofibers for Delivery of Vitamin B12

Nanofibers made of natural proteins have caught the increasing attention of food scientists because of their edibility, renewability, and possibility for various applications. The objective of this study was to prepare nanofibers based on pumpkin leaf protein concentrate (LPC) as a by-product from some crops and gelatin as carriers for vitamin B12 using the electrospinning technique. The starting mixtures were analyzed in terms of viscosity, density, surface tension, and electrical conductivity. Scanning electron micrographs of the obtained nanofibers showed a slight increase in fiber average diameter with the addition of LPC and vitamin B12 (~81 nm to 109 nm). Fourier transform infrared spectroscopy verified the physical blending of gelatin and LPC without phase separation. Thermal analysis showed the fibers had good thermal stability up to 220 °C, highlighting their potential for food applications, regardless of the thermal processing. Additionally, the newly developed fibers have good storage stability, as detected by low water activity values ranging from 0.336 to 0.376. Finally, the release study illustrates the promising sustained release of vitamin B12 from gelatin-LPC nanofibers, mainly governed by the Fickian diffusion mechanism. The obtained results implied the potential of these nanofibers in the development of functional food products with improved nutritional profiles.

Optimization of extraction parameters of protein isolate from milk thistle seed: Physicochemical and functional characteristics

In the current study, optimization of milk thistle protein extraction parameters was carried out in terms of purity and yield. In addition, the characterization of proteins isolated from milk thistle seeds was conducted. The optimal conditions for achieving the highest purity of protein (MTP) from milk thistle seeds were identified as extraction pH 9.47, temperature 30°C, and extraction time 180 min. Conversely, optimal values for overall protein yield (MTY) were determined at extraction pH 12, temperature 50°C, and extraction time 167 min. The proteins obtained under these two sets of conditions (MTP and MTY) demonstrated comparable oil absorption capacity (OAC), foaming, and emulsifying capabilities, as well as stability, aligning with findings from previous studies on seed protein. Both proteins had the highest protein solubilities at pH 11. Both proteins' zeta potentials were closest to zero at pH 4, demonstrating their closeness to the isoelectric point. MTP and MTY had poorer antioxidant capabilities than the other protein isolates/concentrates. MTP and MTY contain high β sheet concentrations that might enhance thermal stability and lower the digestibility of proteins. In conclusion, the protein extraction process demonstrated a high potential for achieving both substantial yield and remarkable purity with some decent technological and functional properties, thus holding promise for various applications in diverse fields.

Development of Vitamin C-Loaded Electrospun Nanofibers of Mixture of Polysaccharides of Pullulan/Xanthan Gum for Fast Dissolving Oral Film Applications

In this study, polysaccharide-based nanofibrous fast dissolving oral films (FDOFs) were developed using pullulan (PUL) and xanthan gum (XG) via electrospinning. The edible, continuous, and bead-free nanofibers with average diameters ranging from 181.17 nm to 260.84 nm were prepared. The morphological, thermal, mechanical, and water-soluble properties of the nanofibrous FDOFs were characterized. For prospective future applications of the developed PUL/XG FDOFs, a model nutrient of vitamin C (VC) was encapsulated into the FDOFs. The success of VC encapsulation was confirmed by Fourier transform infrared spectroscopy. The encapsulation efficiency of VC was above 85% by ultraviolet-visible spectrophotometer. The amorphous structure of PUL/XG in the nanofibers film was demonstrated by X-ray diffractometer. In addition, the edible FDOFs could dissolve in water within 3 s. The nanofibers film we prepared could be used as nutrient or drug carriers and edible packaging film.

Multifunctional electrospun membranes with hydrophilic and hydrophobic gradients property for wound dressing

Achieving sustained and stable release of macromolecular antibacterial agents and unidirectional transport of liquids in targeted environment is still a challenge to be addressed in the management of wounds with large amounts of tissue exudates. In this work, a multilayer electrospun membrane (ethylcellulose-ethylcellulose/gelatin-quercetin/Eudragit L-100/polyethylene glycol, EC-EC/Gel-Q/EL/PEG) was designed with hydrophobic-hydrophilic gradients and drug sustained-release properties controlled by self-pumping effect and prepared using sequential electrospinning technology. The capillary force of different layers in the multilayer membrane could be controlled by precisely tuning the polymer concentrations of the inner and middle layers to extract water directly from hydrophobic inner ethylcellulose (EC) layer to hydrophilic middle ethylcellulose/gelatin (EC/Gel) layer. The droplets could not penetrate the hydrophobic side, but the drug molecules in the outer layer quercetin-loaded Eudragit L-100 (Q/EL/PEG) membrane moved after absorbing a large amount of water. The drug release behavior of multilayer wound dressing mainly followed the Korsmeyer-Peppas model. This multifunctional electrospun membrane could rapidly drive the biofluid outflow, effectively block the invasion of external contaminants and continuously release anti-inflammatory drugs, without any obvious cytotoxicity to mouse fibroblast cells. Hence, the above results indicate the excellent therapeutic potential of the proposed biomaterial as a wound dressing for diabetic patients.