Influence of plasticizers on the water sorption isotherms and water vapor permeability of chicken feather keratin films

Nutritional and technological potential of chicken feathers for the food industry

1. The production of chicken meat has resulted in high volumes of byproducts, such as feathers, bones, skin, viscera, and feet. The structure of feathers is one of the most complex among vertebrates, with a central axis and lateral filamentary structures, providing rigidity, lightness, and flexibility. Chicken feathers are composed of proteins, lipids, and water, with the highest protein content, especially keratin, which is responsible for the material's rigidity.2. Industries still make little use of feathers, which are generally intended for the production of flour or organic fertilisers. These are low added value products, and discarded feathers can harm the environment.3. Keratin extraction techniques and resulting protein hydrolysates have been studied in chicken feathers. Acid, alkaline or enzymatic hydrolysis is the most commonly used method for obtaining molecules with functional properties such as antioxidant, antimicrobial, antihypertensive and antidiabetic activity.4. The development of keratin-based biodegradable films represents an area of interest for reducing the economic and environmental impacts caused by inappropriate disposal of feathers.

Valorization of feather waste in Brazil: structure, methods of extraction, and applications of feather keratin

This systematic review presents the potential of using feather waste as a β-keratin source, including the Brazilian scenario in the generation of this byproduct. The structure and properties of α- and β-keratin, the methods commonly reported to extract keratin from poultry feathers, and applications of feather keratin-based materials are also covered in this review. The literature search for poultry production data in Brazil was conducted for the last 2 years, for the period 2021-2022. A broad literature search for extraction methods and applications of feather keratin was done for the period 2001-2022. The poultry industry is one of the largest sectors of the food industry, and Brazil was the third-largest world producer of chicken meat with more than six billion chickens slaughtered in 2021. Poultry feathers constitute about 7% weight of broilers; thus, it can be estimated that about one million tons of poultry feathers were generated in Brazil in 2021, and the improper disposal of this byproduct contributes to environmental problems and disease transmission. The most common method of reusing feathers is the production of feather meal. From economic and environmental points of view, it is advantageous to develop processes to add value to this byproduct, including the extraction of keratin. Among natural biodegradable polymers, keratin-based materials have revolutionized the field of biomaterials due to their biocompatibility and biodegradability, allowing their application in biomedical, pharmaceutical, chemical, and engineering areas.

Preparation and Characterization of Chinese Leek Extract Incorporated Cellulose Composite Films

This study aimed to prepare microcrystalline cellulose (MCC) films with good mechanical properties via plasticization using a Chinese leek (CL, Allium tuberosum) extract. The microstructure, crystal structure, mechanical properties, barrier ability, and thermal properties of the films were investigated. The chemical structure analysis of CL extract showed the existence of cellulose, lignin, and low-molecular-weight substances, such as polysaccharides, pectins, and waxes, which could act as plasticizers to enhance the properties of MCC:CL biocomposite films. The results of scanning electron microscopy and atomic force microscopy analyses indicated the good compatibility between MCC and CL extract. When the volume ratio of MCC:CL was 7:3, the MCC:CL biocomposite film exhibited the best comprehensive performance in terms of water vapor permeability (2.11 × 10^-10 g/m·s·Pa), elongation at break (13.2 ± 1.8%), and tensile strength (24.7 ± 2.5 MPa). The results of a UV absorption analysis demonstrated that the addition of CL extract improved the UV-shielding performance of the films. Therefore, this work not only proposes a facile method to prepare MCC films with excellent mechanical properties via plasticization using CL extract but also broadens the potential applications of MCC films in the packaging area.

Ductile keratin films from deep eutectic solvent-fractionated feathers

Feathers, an industrial by-product, are a valuable source of keratin that could be used, for example, in the preparation of films for biomedical and packaging applications. However, the utilisation of feather keratin requires scalable processes to convert feathers into a feasible keratin stream. This paper shows how deep eutectic solvent (DES) fractionated feathers could be converted into strong films. In the DES fractionation process, two keratin fractions with different molecular weights were obtained. The films made of the high molecular weight keratin fraction had better mechanical properties and stability against moisture than the films made of the low molecular weight keratin fraction. The strength properties were further improved by cross-linking the keratin with diglycidyl ether enabling the formation of a uniform keratin network, whereas glutaraldehyde did not show a clear cross-linking effect. These keratin films could be used, for example, in food packaging or medical applications such as wound care.

Effects of Nopal Mucilage (Opuntia ficus-indica) as Plasticizer in the Fabrication of Laminated and Tubular Films of Extruded Acetylated Starches

Normal and acetylated rice and waxy maize starches with a blend of nopal mucilage (Opuntia ficus-indica) and glycerol were used for the preparation of laminated and tubular films by extrusion and blown extrusion, respectively. The composition of the formulation was 70% starch (normal or acetylated), 20% glycerol, and 10% nopal mucilage ( $w/w$ ). The degrees of substitution (DS) for acetylated rice starch (0.94) and waxy maize starch (0.76) present high potential for use as a polymeric matrix in packing materials. The use of nopal mucilage can improve the processability of extruded and tubular films by favoring the increase of some mechanical and functional properties. The films elaborated with nopal mucilage and glycerol present a homogeneous relief without breaking, adhesiveness, and contraction once formed. The elongation values of acetylated waxy maize starch films (33%) were higher than those of rice acetylated films (17%), while the blown films presented a 30% decrease in tensile strength, compared to the laminated films. Acetylation generated more hydrophobic material for the rice starch sample, which can be evidenced by a decreased solubility of the laminated films. Films of both sources of acetylated starch showed a significant decrease in water vapor permeability and showed a plasticized starch disposition-type layer without unmelted starch granules.

Fabrication and characterization of chicken feather keratin/polysaccharides blended polymer coated nonwoven dressing materials for wound healing applications

In this research work, three kinds of nonwoven wound dressings were developed from chicken feather keratin (CFK-NW), keratin‑sodium alginate (CFK-SA-NW) and keratin-chitosan (CFK-CS-NW) and characterized using FTIR and SEM. The physical characteristics such as air permeability, thickness and areal density test results revealed the suitability of fabricated materials for wound dressing applications. CFK-SA-NW and CFK-CS-NW indicated a positive antibacterial effect against Gram's positive Staphylococcus aureus and Gram's negative Klebsiella pneumoniae and Escherichia coli bacteria with the zone of inhibition enhanced over >2.0 cm. Moreover, the biomedical potentials of dressing materials has been investigated by cell viability and cytotoxicity tests. Further, the wound healing ability was demonstrated using in vivo model (Albino Wistar rat). The fabricated materials exhibited good support for cell viability and a strong cytocompatibility. Furthermore, the hundred percent wound healing ability of CFK-CS-NW, CFK-SA-NW, CFK-NW and untreated control rats was observed at 15, 17, 21 and 23 days, respectively, Moreover, the wound healing potential of CFK-CS-NW and CFK-SA-NW was found to be better than that of CFK-NW and control group of rats. The outcome of the present study discloses the prospective applications of the developed materials as wound dressing biomaterial.

Keratin: dissolution, extraction and biomedical application

Keratinous materials such as wool, feathers and hooves are tough unique biological co-products that usually have high sulfur and protein contents. A high cystine content (7-13%) differentiates keratins from other structural proteins, such as collagen and elastin. Dissolution and extraction of keratin is a difficult process compared to other natural polymers, such as chitosan, starch, collagen, and a large-scale use of keratin depends on employing a relatively fast, cost-effective and time efficient extraction method. Keratin has some inherent ability to facilitate cell adhesion, proliferation, and regeneration of the tissue, therefore keratin biomaterials can provide a biocompatible matrix for regrowth and regeneration of the defective tissue. Additionally, due to its amino acid constituents, keratin can be tailored and finely tuned to meet the exact requirement of degradation, drug release or incorporation of different hydrophobic or hydrophilic tails. This review discusses the various methods available for the dissolution and extraction of keratin with emphasis on their advantages and limitations. The impacts of various methods and chemicals used on the structure and the properties of keratin are discussed with the aim of highlighting options available toward commercial keratin production. This review also reports the properties of various keratin-based biomaterials and critically examines how these materials are influenced by the keratin extraction procedure, discussing the features that make them effective as biomedical applications, as well as some of the mechanisms of action and physiological roles of keratin. Particular attention is given to the practical application of keratin biomaterials, namely addressing the advantages and limitations on the use of keratin films, 3D composite scaffolds and keratin hydrogels for tissue engineering, wound healing, hemostatic and controlled drug release.

Prediction of Mold Spoilage for Soy/Polyethylene Composite Fibers

Mold spoilage was determined over 109 days on soy/PE fibers held under controlled temperatures (T) ranging from 10°C to 40°C and water activities(aw)from 0.11 to 0.98. Water activities were created in sealed containers using saturated salt solutions and placed in temperature-controlled incubators. Soy/PE fibers that were held at 0.823awor higher exhibited mold growth at all temperatures. As postulated, increased water activity (greater than 0.89) and temperature (higher than 25°C) accelerated mold growth on soy/PE fibers. A slower mold growth was observed on soy/PE fibers that were held at 0.87awand 10°C. A Weibull model was employed to fit the observed logarithmic values ofT, aw, and an interaction termlog⁡T×log⁡awand was chosen as the final model as it gave the best fit to the raw mold growth data. These growth models predict the expected mold-free storage period of soy/PE fibers when exposed to various environmental temperatures and humidities.

Environmentally sustainable fibers from regenerated protein

Concerns for the environment and consumer demand are driving research into environmentally friendly fibers as replacements for part of the 38 million tonnes of synthetic fiber produced annually. While much current research focuses on cellulosic fibers, we highlight that protein fibers regenerated from waste or byproduct sources should also be considered. Feather keratin and wheat gluten may both be suitable. They are annually renewable, commercially abundant, of consistent quality, and have guaranteed supply. They contain useful amino acids for fiber making, with interchain cross-linking possible via cysteine residues or through the metal-catalyzed photocrosslinking of tyrosine residues. Previous commercially produced fibers suffered from poor wet strength. Contemporary nanoparticle and cross-linking technology has the potential to overcome this, allowing commercial production to resume. This would bring together two existing large production and processing pipelines, agricultural protein production and textile processing, to divert potential waste streams into useful products.