Effect of ultrasound on keratin valorization from chicken feather waste: Process optimization and keratin characterization

Chemical composition and techno-functional properties of high-purity water-soluble keratein and its enzymatic hydrolysates

This study compared the effectiveness of urea-containing and urea-free L-cysteine solutions in extracting high-quality feather keratin and evaluated commercial proteases for producing keratin-derived bioactive peptides. The urea-assisted extraction was crucial for achieving high structural integrity and yield of soluble keratin. The keratin isolate exhibited oil-holding capacity of 9.37 g/g, foaming capacity of up to 127 %, and emulsifying capacity of up to 49 %. Its proteolysis with trypsin, chymotrypsin, pepsin and subtilisin resulted in peptides with average molecular weight between 2.10 and 5.96 kDa and degree of hydrolysis from 6 to 36 %. The subtilisin hydrolysate had the highest degree of hydrolysis, 63 % of peptides <1 kDa, and excellent solubility across a wide pH range, but negligible water and oil-binding, foaming, and emulsifying properties. This study highlights the need to optimize each step in keratin extraction and hydrolysis processes to produce high-quality bioactive keratin preparations for diverse applications, including food and pharmaceutical.

Systematic preparation of animal-derived glycosaminoglycans: Research progress and industrial significance

Impurities and isomerized polysaccharides affect the analytical accuracy of glycosaminoglycans (GAGs) structure and bioactivity, hindering their application in food and medicine. Preparing homogeneous GAGs components is essential for exploring structure-potency relationships and facilitating industrial production. This review primarily summarizes research on animal-derived GAGs preparation over the past five years, standardizing the preparation process into four operational units: pre-extraction treatment, extraction of crude polysaccharides, refinement of crude polysaccharides, and separation of GAGs components. Analyzed for scientific research and industrial production, the principles and application conditions of traditional means and novel techniques to preparing GAGs are comprehensively emphasized, exploring the effects of different treatments on biological activity and structure. Current challenges and development trends are illuminated. This review aims to lay a foundation for the in-depth study of GAGs structure, bioactivity, and function, providing theoretical references for the comprehensive utilization of animal raw materials and the development of animal polysaccharide deep-processing industries.

Keratin/chitosan film promotes wound healing in rats with combined radiation-wound injury

Human hair keratin, a natural protein derived from human hair, has emerged prominently in the field of wound repair, showcasing its unique regenerative capabilities and extensive application potential. However, it is a challenge for the keratin to efficiently therapy the impaired wound healing, such as combined radiation-wound injury. Here, we report a keratin/chitosan (KRT/CS) film for skin repair of chronic wounds in in rats with combined radiation-wound injury. In brief, the KRT/CS film was characterized by scanning electron microscopy (SEM), mechanical property analysis, water absorption, and swelling analysis. A rat model of combined radiation-wound injury was employed to evaluate the therapeutic efficacy of the KRT/CS film. Finally, the systemic biotoxicity of KRT/CS film was assessed through histological analysis. The surface of KRT/CS film was uniform and smooth compared with the KRT film, and the mechanical property, swelling rate and water absorption rate of KRT/CS film were significantly improved, which can meet the application requirements of wound excipient dressing. Furthermore, the combined radiation-wound injury in rats was established that the wound closure rate was achieved 74.46% after 14 days of treatment with KRT/CS film, comparing to the single KRT membrane and commercially available Band-Aids. Histological analysis demonstrated that the amount of angiogenesis and collagen deposition in wounds treated with KRT/CS were significantly improved. These findings demonstrate the KRT/CS film as a promising therapeutic agent for combined radiation-wound injury.

Unlocking the Potential of Keratin: A Comprehensive Exploration from Extraction and Structural Properties to Cross-Disciplinary Applications

The rapid expansion of the livestock and poultry industry has led to a considerable increase in slaughter byproducts; however, exploring their potential applications still needs to be improved. These underutilized byproducts, which include nails, hides, skins, and bones, represent a significant loss of valuable biological resources. Among these materials, keratin has garnered considerable attention due to its unique properties as a natural biopolymer. Keratin exhibits outstanding mechanical properties and biocompatibility and has attracted increasing attention for its recovery and conversion into relevant application materials. However, natural keratin typically has a high sulfur content, complex 3D structure, and abundant hydrogen and disulfide bonds, which cause challenges in application. Current extraction for keratin includes physical, chemical, biological, and hybrid approaches. Combining multiple methods synergistically enhances protein extraction efficiency and purity, and facilitates the exploration of structure and functional properties. This review encompasses the structural characteristics, properties, extraction methods, and research progress related to keratin. The preparation and application of keratin composite materials in different forms, such as fibers, films, hydrogels, and scaffolds, are illustrated. Applications in several fields, including biomedicine, flexible electronic components, environmental materials and food packaging are discussed. Hopefully, this paper will provide a comprehensive understanding and guidance for further development and application of keratin materials.

Recovery of keratin from feather meal: a new route to valorize an agro-industrial co-product

The valorization of agro-industrial by-products/co-products represents a sustainable pathway to produce high-value biomaterials. Feather meal is an agro-industrial co-product derived from clean and undecomposed poultry feathers processed under high heat and pressure that offers an economically viable and scalable alternative for keratin extraction compared to native feathers. This study explores the recovery of keratin from feather meal through an optimized alkaline hydrolysis process, achieving a yield of 20 wt.% at 15°C and 90 min of extraction by using 2 mol L-1 sodium hydroxide solution. A negative temperature dependence was observed in keratin extraction yield, suggesting the occurrence of thermal degradation at elevated temperatures. Protein analyses by different techniques confirmed the characteristic diffraction peaks, functional groups, and elemental composition (carbon, nitrogen, oxygen, and sulphur) of feather keratin. The extracted keratin presented a low molar mass of 9 kg mol-1. Considering the circular economy principles, this work proposes a novel valorization route for feather meal and highlights its potential in creating value-added materials for several applications in medicine, pharmaceuticals, and engineering areas.

Effects of ultrasonic waves of different powers on the physicochemical properties, functional characteristics, and ultrastructure of bovine liver peptides

In recent years, ultrasound has emerged as a widely used technology for modifying proteins/peptides. In this study, we focused on the intrinsic mechanism of ultrasound-induced modification of bovine liver peptides, which were treated with ultrasound power of 0, 100, 200, 300, 400, and 500 W, and their physicochemical and functional properties, as well as ultrastructures, were investigated. The results show that ultrasound mainly affects hydrogen bonding and hydrophobic interactions to change the conformation of proteins and unfolds proteins through a cavitation effect, leading to an increase in biological activity. Fourier infrared spectroscopy showed that ultrasound inhibited the formation of hydrogen bonds and reduced intermolecular cross-linking. Molecular weight distribution showed that the antioxidant components of bovine liver polypeptides were mainly concentrated in fractions of 500-1,000 Da. Maximum values of ABTS (82.66 %), DPPH (76.02 %), chelated iron (62.18 %), and reducing power (1.2447) were obtained by treating bovine liver polypeptides with 500 W ultrasound. Combined with the scanning electron microscopy results, with the intervention of ultrasound, the impact force generated by ultrasonication may lead to the loosening of the protein structure, which further promotes the release of antioxidant peptides, and these findings provide new insights into the application of ultrasound in the release of antioxidant peptides from bovine liver.

Enhanced Delivery of Biomolecules into Caco2 Cells Based on the Cell-Penetrating Ability of Keratin Peptides

Keratin, as a promising bioresource, possesses significant potential for diverse biological applications due to its favorable biocompatibility, low toxicity, biodegradability, and cell adhesion ability. However, there are few studies on the cell-penetrating ability of keratin peptides (KEPs) for biomolecule delivery. Therefore, this study explored the cell-penetrating ability of KEPs with different molecular weights (Mw) on Caco2 cells using fluorescein-labeled insulin (FITC-INS) as the target intracellular biomolecule. The potential cell-penetrating mechanism was elaborated by combining cellular investigation with the physicochemical characterization of KEPs. The result shows that the KEPs <3 kDa (KEP1) exhibited the highest cell-penetrating ability at 2 mg/mL, allowing efficient delivery of FITC-INS into Caco2 cells without covalent bonding. The cellular uptake mechanism was energy-dependent, mainly involving macropinocytosis. The further fractionation of KEP1 reveals that the most effective components consisted of 8-19 amino acids, including specific hydrophobic peptides (e.g., RVVIEPSPVVV and IIIQPSPVVV), PPII amphipathic peptides (e.g., PPPVVVTFP and FIQPPPVVV), and Cys-rich peptides (e.g., LCAPTPCGPTPL and CLPCRPCGPTPL). Additionally, analysis of the secondary and tertiary structure and amino acid composition illustrated that KEP1 exhibited rich hydrophobic residues and disulfide bonds, which probably contributed to its cell-penetrating ability, as opposed to its small particle size and electrostatic interactions. This study reveals the cell-penetrating ability of KEPs, thus highlighting their potential as biomaterials for noncovalently delivering biomolecules.

Waste chicken feather biofiller reinforced bioepoxy resin based biocomposites - A waste to wealth experimental approach

Utilizing poultry wastes, particularly chicken feathers, in biopolymer composites is seen as an important aspect in lowering the environmental pollution and paving a new path to sustainability. The main objective of this experimental study is to develop polymer composites reinforced with waste chicken feather fillers and evaluate their physical, mechanical, and thermal characteristics. The composites were fabricated through an open mold casting process using bio epoxy (SR-33 Greenpoxy) as the matrix and chicken feather filler as a reinforcement in three distinct weight fractions (2.5, 5, and 7.5 wt%). To evaluate the effects of filler content on the mechanical properties of the fabricated bio-epoxy composites, they were subjected to tensile, flexural, impact, and hardness tests. The findings from the experimental studies demonstrated that the composites containing 2.5 wt% of chicken feather filler had improved mechanical properties, thermal stability, and crystallization behaviour. The thermal attributes of samples included a greater melting point, lower recrystallization temperature, higher glass transition temperature, and quicker crystallization rates. The Scanning Electron Microscope analysis of the fracture surface morphology of the biocomposites showed a better interfacial adhesion between the filler and matrix. It could be concluded from the results that the waste chicken feather can be used as potential filler reinforcements for begetting natural composites for various low- and medium-density structural and non-structural applications.