Gelatins as emulsifiers for oil-in-water emulsions: Extraction, chemical composition, molecular structure, and molecular modification

Effect of protein oxidation on the structure and emulsifying properties of fish gelatin

This study aimed to investigate the effect of oxidation on fish gelatin and its emulsifying properties. Fish gelatin was oxidized with varying concentrations of H2O2 (0-30 mM). Increased concentrations of the oxidant led to a decrease in amino acids in the gelatin, including glycine, lysine, and arginine. Additionally, the relative content of ordered secondary structure and triple helix fractions decreased. Zeta potential decreased, while particle size, surface hydrophobicity, and water contact angle increased. Regarding emulsifying behavior, oxidation promoted the adsorption of gelatin to the oil-water interface and reduced interfacial tension. With increased degrees of oxidation, the zeta potential and size of the emulsion droplets decreased. The oxidized gelatin exhibited better emulsifying activity but worse emulsifying stability. Based on these results, a mechanism for how oxidation affects the emulsifying properties of gelatin was proposed: the increase in gelatin's hydrophobicity and the decrease in triple helix structure induced by oxidation reduced the interfacial tension at the oil-water interface. This promoted protein adsorption at the oil-water interface, allowing the formation of smaller oil droplets and enhancing gelatin's emulsifying activity. However, the decrease in electrostatic repulsion between emulsion droplets and the decrease in solution viscosity increased the flocculation and aggregation of oil droplets, ultimately weakening the emulsifying stability of gelatin.

Comprehensive review on the application of omics analysis coupled with Chemometrics in gelatin authentication of food and pharmaceutical products

Gelatin is a protein molecule that can be hydrolyzed from collagen, animal bones, skin and it easily soluble in water. Source animals for gelatin ingredients must be evaluated, as well as their halal status. The omics method towards gelatin authentication in food and pharmaceutical products has several advantages, including high sensitivity and reliable data. Omics investigation employs the process of breaking down substances into small particles, hence enhancing the ability to detect a greater number of compounds. Omics study has the capability to identify substances at the subclass level, which makes it highly suitable for gelatin authentication. Gelatin lipids, metabolites, proteins, and volatile chemicals can be utilized as references to authenticate gelatin. In adopting gelatin authentication, lipidomics, metabolomics, proteomics, and volatilomics must be combined with chemometrics for data interpretation. Chemometrics can convert omics analysis data into easily viewable data. Chemometric approaches capable of presenting omics analysis data for gelatin authentication include PCA, HCA, PLS-DA, PLSR, SIMCA, and FACS. Visually chemometrically explain the differences in gelatin from different animal sources. The combination of omics analysis and chemometrics is a very promising technology for gelatin authentication in food and pharmaceutical products.

Robust holocellulose barrier films from agricultural byproduct of Camellia Oleifera shells through dilute acid and ultrasonic treatments

Camellia oleifera shells (COS) are commonly discarded as an agricultural by-product. Effective utilization of COS can not only reduce environmental pollution but also enhance the value of the tea-oil industry. The unique composition of COS, with high hemicellulose and low cellulose content, makes it suitable for the production of film materials. In this study, COS holocellulose (COSH) was isolated and treated with four different types of dilute acids (15 % acetic acid, gallic acid, citric acid, and 0.5 % sulfuric acid, 1-24 h, 75°-105 °C) to produce barrier films. Among these, citric acid treatment resulted in the strongest and toughest film. By incorporating a brief ultrasonic pretreatment (15 min, 300 w) prior to the citric acid reaction, translucent films were achieved with impressive mechanical properties, showing tensile strength, Young's modulus and elongation at break up to 75.72 MPa, 3306.11 MPa and 8.01 %, respectively. Through a comprehensive analysis of the structure-property relationships, it was discovered that the combined effects of ultrasonic and citric acid treatments disrupted the integrated holocelluose fiber structure and facilitated the formation of a robust hydrogen bond network during the film preparation process. The resulting films exhibited enhanced water vapor barrier properties, antioxidant capacity, and complete decomposition in soil, suggesting the potential application as wraps for fresh fruits.

A Review of Modified Gelatin: Physicochemical Properties, Modification Methods, and Applications in the Food Field

Gelatin is a significant multifunctional biopolymer that is widely utilized as a component in food, pharmaceuticals, and cosmetics. Numerous functional qualities are displayed by gelatin, such as its exceptional film-forming ability, gelling qualities, foaming and emulsifying qualities, biocompatibility and biodegradable qualities. Due to its unique structural, physicochemical, and biochemical characteristics, which enhance nutritional content and health benefits as well as the stability, consistency, and elasticity of food products, gelatin is utilized extensively in the food business. Additionally, gelatin has demonstrated excellent performance in encapsulating, delivering, and releasing active ingredients. Gelatin's various modifications, such as chemical, enzymatic, and physical processes, were analyzed to assess their impact on gelatin structures and characteristics. Hopefully, gelatin will be more widely used in various applications after modification using suitable methods.

Preparation of 1,2-benzenedialdehyde-crosslinked oligo-gelatin conjugates and poly-gelatin nanoparticles to stabilize traditional and Pickering emulsions, respectively

This research aimed to develop a desolvation and 1,2-benzenedialdehyde crosslinking method to prepare crosslinked gelatin substances for emulsion stabilization. The oligo-gelatin conjugates and poly-gelatin nanoparticles could be formed at the 1,2-benzenedialdehyde concentration of 50 g/L and ≥ 150 g/L, respectively. The formation mechanism involved intra/inter-molecular amine-benzenedialdehyde-thiol and amine-benzenedialdehyde-amine crosslinking reactions. With increasing 1,2-benzenedialdehyde preparation concentrations (50-450 g/L), the crosslinked gelatin substance sizes increased from 81.5 ± 20.1 nm to 105.5 ± 20.8 nm in the dried state, and increased (from 35 ± 8 nm to 220 ± 36 nm) then decreased to 115 ± 28 nm in the water. Furthermore, the fish oil emulsions stabilized by the crosslinked gelatin substances showed different creaming stability: 250 g/L (43.5 ± 1.5 %) > 350 g/L (41.4 ± 1.0 %) > 450 g/L (37.5 ± 2.2 %) > 150 g/L (11.2 ± 0.4 %) > 50 g/L (0.0 ± 0.0 %). The results suggested this method was useful for preparing oligo-gelatin conjugates and poly-gelatin nanoparticles to stabilize traditional and Pickering emulsions, respectively.

High internal phase emulsion stabilized by soy protein isolate-Rutin complex: Rheological properties, bioaccessibility and in vitro release kinetics

High internal phase emulsions (HIPEs) are promising carrier materials for encapsulating and delivering hydrophobic bioactive compounds. By strategically adjusting the composition, particle size, or charge of HIPEs, it is possible to enhance both their stability and the bioaccessibility of hydrophobic polyphenols encapsulated within them. In this study, different soy protein isolate (SPI)-rutin (SPI-R) complexes (formed under various preheating temperatures) were used to stabilize HIPEs, while the particle size, and charge of HIPEs was further adjusted through different homogenization rates. The results demonstrated that an optimal preheating temperature of 70 °C for the complex and a homogenization rate of 15,000 rpm for HIPEs enhanced the stability of the entire emulsion system by producing more uniform and smaller droplet distribution with improved rheological properties. Furthermore, in vitro digestion experiments showed that HIPEs stabilized by the SPI-R complexes (HSR) at optimal homogenization rate had better loading efficiency (98.68 %) and bioaccessibility compared to other groups. Additionally, fitting results from release kinetics confirmed that rutin encapsulated by HSR could achieve sustained release effect. Overall, these findings suggest that HSR has great potential as an effective vehicle for delivering hydrophobic bioactive compounds like rutin within the food industry.

Fluorogenic in-situ Labelling of Gelatin Polymer in Aqueous Solution and Hydrogel

Gelatin polymers made from partially degraded collagen are important biomaterials, but their in-situ analysis suffers from uncontrollable covalent labelling and poor spatial-temporal imaging resolution. Herein, three tetrazolate-tagged tetraphenylethylene fluorophores (TPE-TAs) are introduced for practical fluorogenic labelling of gelatin in aqueous phase and hydrogels. These probes with aggregation-induced emission characteristics offer negligible background and elicit turn-on fluorescence by simply mixing with the gelatin in aqueous phase, giving a detection limit of 0.15 mg/L over a linear dynamic range up to 100 mg/L. This method does not work for collagens and causes minimal interference with gelatin properties. Mechanistic studies reveal a key role for multivalent electrostatic interactions between the abundant basic residues in gelatin (e. g., lysine, hydroxylysine, arginine) and anionic tetrazolate moieties of the lipophilic fluorophore synergistically in spatially rigid macromolecular encapsulation to achieve fluorogenic labelling. The AIE strategy by forming non-covalent fluorophore-gelatin complexes was developed for novel hydrogels that exhibited reversible fluorescence in response to dynamic microstructural changes in the hydrogel scaffold upon salting-in/out treatments, and enabled high spatial-temporal imaging of the fiber network in lyophilized samples. This work may open up avenues for in-situ imaging analysis and evaluation of gelatin-based biomaterials during processes such as in vivo degradation and mineralization.

Exploring Protein-Based Carriers in Drug Delivery: A Review

Drug delivery systems (DDSs) represent an emerging focus for many researchers and they are becoming progressively crucial in the development of new treatments. Great attention is given to all the challenges that a drug has to overcome during its journey across barriers and tissues and all the pharmacokinetics modulations that are needed in order to reach the targeting sites. The goal of these pathways is the delivery of drugs in a controlled way, optimizing their bioavailability and minimizing side effects. Recent innovations in DDSs include various nanotechnology-based approaches, such as nanoparticles, nanofibers and micelles, which provide effective targeted delivery and sustained release of therapeutics. In this context, protein-based drug delivery systems are gaining significant attention in the pharmaceutical field due to their potential to revolutionize targeted and efficient drug delivery. As natural biomolecules, proteins offer distinct advantages, including safety, biocompatibility and biodegradability, making them a fascinating alternative to synthetic polymers. Moreover, protein-based carriers, including those derived from gelatin, albumin, collagen, gliadin and silk proteins, demonstrate exceptional stability under physiological conditions, and they allow for controlled and sustained drug release, enhancing therapeutic efficacy. This review provides a comprehensive overview of the current trends, challenges, and future perspectives in protein-based drug delivery, focusing on the types of proteins adopted and the techniques that are being developed to enhance their functionality in terms of drug affinity and targeting capabilities, underscoring their potential to significantly impact modern therapeutics.

Oleogel Systems for Chocolate Production: A Systematic Review

In response to the growing demand for healthier food options, this review explores advances in oleogel systems as an innovative solution to reduce saturated fats in chocolates. Although appreciated for its flavor and texture, chocolate is high in calories, mainly due to cocoa butter (CB), which is rich in saturated fats. Oleogels, three-dimensional structures formed by structuring agents in edible oils, stand out in terms of mimicking saturated fats' physical and sensory properties without compromising the quality of chocolate. This study reviews how oleogels could improve chocolate's stability and sensory quality, exploring the potential of pectin-rich agro-industrial by-products as sustainable alternatives. It also explores the need for physicochemical evaluations of both oleogel and oleogel-based chocolate.

Fish Gelatin-Based Flexible and Self-Healing Hydrogel Modified by Fe2(SO4)3

The application of fish gelatin (FG) is limited due to its poor mechanical properties and thermal stability, both of which could be significantly improved by gellan gum (GG) found in previous research. However, the FG/GG composite hydrogel was brittle and easily damaged by external forces. It was found that the composite hydrogel with Fe2(SO4)3 showed good flexibility and self-healing properties in the pre-experiment. Thus, the synergistic effect of FG, GG and Fe2(SO4)3 on the mechanical properties of the composite hydrogel was investigated in this study. According to one-way experiments, response surface tests and Texture Profile Analysis, it was found that under the optimum condition of FG concentration 186.443 g/L, GG concentration 8.666 g/L and Fe2(SO4)3 concentration 56.503 g/L, the springiness of the composite cylindrical hydrogel with the height of 25 mm formed in 25 mL beakers (bottom diameter 30 mm) was 7.602 mm. Determination of the rheological properties, compression performance, adhesive performance and self-healing properties showed that the composite hydrogel had good thermal stability, flexibility and self-healing properties with good adhesion, skin compliance and compressive strength, and it was easy to remove. The composite hydrogel showed strong antimicrobial activity against A. salmonicida and V. parahaemolyticus. All hydrogels showed a uniform and porous structure. The 3D structure of the composite hydrogel was much looser and more porous than the pure FG hydrogel. The flexible and self-healing composite hydrogel with some antimicrobial activity is suitable for the development of medical dressings, which broadens the applications of the composite hydrogel.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Effects of polyphenol and gelatin types on the physicochemical properties and emulsion stabilization of polyphenol-crosslinked gelatin conjugates

Herein, six types of polyphenol-crosslinked gelatin conjugates (PGCs) with ≥ two gelatin molecules were prepared using a covalent crosslinking method with two types of polyphenols (tannic acid and caffeic acid) and three types of gelatins (bovine bone gelatin, cold water fish skin gelatin, and porcine skin gelatin) for the emulsion stabilization. The structural and functional properties of the PGCs were dependent on both polyphenol and gelatin types. The storage stability of the conjugate-stabilized emulsions was dependent on the polyphenol crosslinking, NaCl addition, and heating pretreatment. In particular, NaCl addition promoted the liquid-gel transition of the emulsions: 0.2 mol/L > 0.1 mol/L > 0.0 mol/L. Moreover, NaCl addition also increased the creaming stability of the emulsions stabilized by PGCs except tannic acid-crosslinked bovine bone gelatin conjugate. All the results provided useful knowledge on the effects of molecular modification and physical processing on the properties of gelatins.

Effect of low-frequency ultrasound-assisted acid extraction on gel properties and structural characterization of sheep's hoof gelatin

In this study, we investigated the effects of various low-frequency ultrasound-assisted extraction processes, including ultrasound-assisted acid-soaked water bath extraction (UAW), ultrasound-assisted water bath extraction after acid soaking (AUW), acid-soaked water bath extraction followed by ultrasonics (AWU), and acid-soaked water bath extraction without ultrasound (CON), on the structural properties, thermal stability, gel properties, and microstructure of sheep's hoof gelatin. The results revealed that the primary components of sheep's hoof gelatin consisted of α1-chain, α2-chain (100-135 kDa), and β-chain. In addition, it was observed that among the three sonication groups, sheep's hoof gelatin extracted in the AUW group exhibited the highest yield (27.16 ± 0.41 %), the best gel strength (378.55 ± 7.34 g), and higher viscosity at the same shear rate. The gelling temperature (25.38 ± 0.45 °C) and melting temperature (32.28 ± 0.52 °C) of sheep's hoof gelatin in the AUW group were significantly higher than those in the other groups (p > 0.05). Moreover, our experiments revealed that the sequence of low-frequency ultrasonic pretreatment processes was a crucial factor influencing the gel properties and structural characteristics of sheep's hoof gelatin. Specifically, the acid treatment followed by the ultrasound-assisted approach in the AUW group yielded high-quality and high-yield sheep's hoof gelatin.

Tilapia head gelatins to stabilize fish oil emulsions and the effect of extraction methods

The preparation and use of gelatins from fish by-products have attracted much attention in the field of food science. Herein, four types of tilapia head gelatins were extracted and characterized: hot water-pretreated gelatin (HWG), acetic acid-pretreated gelatin (AAG), sodium hydroxide-pretreated gelatin (SHG), and pepsin enzyme-pretreated gelatin (PEG). The gel strength values followed the order: PEG (74 ± 1 Bloom) > AAG (66 ± 1) > HWG (59 ± 1) > SHG (34 ± 1). The foaming properties, fish oil emulsion viscosity, emulsion activity, and emulsion stabilization ability followed this order: PEG > HWG ≥ AAG > SHG. The effect mechanisms of extraction methods and gelatin concentrations on the emulsion stability involved the interfacial tension, emulsion viscosity, and fat-binding capacity. This work provided important knowledge for analyzing the relations between the structure and function of gelatin. It also provided a high-value application method of fish wastes.

Encapsulation of grape seed oil in oil-in-water emulsion using multilayer technology: Investigation of physical stability, physicochemical and oxidative properties of emulsions under the influence of the number of layers

Many studies have shown that grape seed oil (GSO) is one of the vegetable fats that are plentiful in essential fatty acids and can be used as a fat substitute or to modify fat in food products to reduce saturated fatty acids. However, due to its low solubility and high sensitivity to oxidation, it is necessary to develop delivery systems that can distribute GSO in food more effectively. Recently, the preparation of emulsions using the layer-by-layer (LBL) method has many advantages in delivering lipid-soluble functional compounds. This research was used to check the formation of GSO oil-loaded primary, secondary and tertiary multilayer emulsions stabilized by mixture of anionic gelatin, cationic chitosan, and anionic basil seed gum (BSG) as the aqueous phase at pH 5, prepared using a layer-by-layer electrostatic deposition technique. Multilayer emulsions prepared by GSO and a mixture of gelatin, chitosan, and BSG as the aqueous phase at pH 5. Finally, the effect of the number of layers on the physicochemical properties (particle size, viscosity, turbidity, refractive index, and physical stability) and oxidative stability (peroxide value, thiobarbituric acid value, and fatty acid profile) during the storage time (30 days) at two temperatures 25 °C & 4 °C was investigated. Also, the zeta potential and Fourier transform infrared spectroscopy (FTIR) of mono-layer and multi-layer emulsions were investigated. The results revealed that by increasing the number of layers of multi-layer emulsion of GSO, the stability has improved. Thus, the tertiary emulsion has been more effective than the other two emulsions in maintaining the physicochemical characteristics and stability over time (P < 0.001). Morphological characterization and FTIR spectroscopy results confirmed that gelatin, chitosan, and BSG were successfully loaded into the LBL emulsions. This study can improve the original percept of multilayer emulsions and promulgate their potential applications for the entire encapsulation of essential fatty acids to enrich and prevent peroxide attack.

Multifunctional hydrogel dressing based on fish gelatin/oxidized hyaluronate for promoting diabetic wound healing

Non-healing chronic diabetic wound treatment remains an unsolved healthcare challenge and still threatens patients' lives. Recently, hydrogel dressings based on natural biomaterials have been widely investigated to accelerate the healing of diabetic wounds. In this study, we introduce a bioactive hydrogel based on fish gelatin (FG) as a candidate for diabetic wound treatments, which is a recently emerged substitute for mammalian derived gelatin. The composite hydrogel simply fabricated with FG and oxidized hyaluronate (OHy) through Schiff base reaction could successfully accelerate wound healing due to their adequate mechanical stability and self-healing ability. In vitro studies showed that the fabricated hydrogels exhibited cytocompatibility and could reduce pro-inflammatory cytokine expression such as NO, IL-1β, TNF-α, and PGE2 in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. In addition, the production of reactive oxygen species (ROS), a key marker of free radicals producing oxidative stress, was also reduced by fabricated hydrogels. Furthermore, in vivo experiments demonstrated that the hydrogel could promote wound closure, re-epithelialization, collagen deposition, and protein expression of CD31, CD206, and Arg1 in diabetic mice models. Our study highlights the advanced potential of FG as a promising alternative material and indicates that FOHI can be successfully used for diabetic wound healing applications.

Fish oil-loaded multicore submillimeter-sized capsules prepared with monoaxial electrospraying, chitosan-tripolyphosphate ionotropic gelation, and Tween blending

In order to load fish oil for potential encapsulation of fat-soluble functional active substances, fish oil-loaded multicore submillimeter-sized capsules were prepared with a combination method of three strategies (monoaxial electrospraying, chitosan-tripolyphosphate ionotropic gelation, and Tween blending). The chitosan-tripolyphosphate/Tween (20, 40, 60, and 80) capsules had smaller and evener fish oil cores than the chitosan-tripolyphosphate capsules, which resulted from that Tween addition induced smaller and evener fish oil droplets in the emulsions. Tween addition decreased the water contents from 56.6 % to 35.0 %-43.4 %, increased the loading capacities from 10.4 % to 12.7 %-17.2 %, and increased encapsulation efficiencies from 97.4 % to 97.8 %-99.1 %. In addition, Tween addition also decreased the highest peroxide values from 417 meq/kg oil to 173-262 meq/kg oil. These properties' changes might result from the structural differences between the chitosan-tripolyphosphate and chitosan-tripolyphosphate/Tween capsules. All the results suggested that the obtained chitosan-tripolyphosphate/Tween capsules are promising carriers for fish oil encapsulation. This work also provided useful knowledge to understand the preparation, structural, and physicochemical properties of the chitosan-tripolyphosphate capsules.

Delivery systems designed to enhance stability and suitability of lipophilic bioactive compounds in food processing: A review

Lipophilic compounds, such as flavors, fat-soluble vitamins, and hydrophobic nutrients possess vital properties including antioxidant effects, functional attributes, and nutritional value that can improve human health. However, their susceptibility to environmental factors including heat, pH changes, and ionic strength encountered during food processing poses significant challenges. To address these issues, diverse bioactive delivery systems have been developed. This review explores delivery systems designed to optimize the stability and suitability of lipophilic bioactive compounds in food processing. Extensive literature analysis reveals that tailoring delivery systems with various biopolymers can protect bioactives through steric hindrance and formation of thick interfacial layers on the emulsion surfaces. Thus, the access of oxygen, prooxidants, and free radicals at the emulsion interface could be inhibited, resulting in enhanced processing suitability of bioactives as well as chemical stability under diverse environmental conditions. The insights presented in this review hold immense value for the food and beverage industries.

The Incorporation of Graphene Nanoplatelets in Tung Oil-Urea Formaldehyde Microcapsules: A Paradigm Shift in Physicochemical Enhancement

Tung oil (TO) microcapsules (MCs) with a poly(urea-formaldehyde) (PUF) shell were synthesized via one-step in situ polymerization, with the addition of graphene nanoplatelets (GNPs) (1-5 wt. %). The synergistic effects of emulsifiers between gelatin (gel) and Tween 80 were observed, with gel chosen to formulate the MCs due to its enhanced droplet stability. SEM images then displayed an increased shell roughness of the TO-GNP MCs in comparison to the pure TO MCs due to the GNP species on the shell. At the same time, high-resolution transmission electron microscopy (TEM) images also confirmed the presence of GNPs on the outer layer of the MCs, with the stacked graphene layers composed of 5-7 layers with an interlayer distance of ~0.37 nm. Cross-sectional TEM imaging of the MCs also confirmed the successful encapsulation of the GNPs in the core of the MCs. Micromanipulation measurements displayed that the 5% GNPs increased the toughness by 71% compared to the pure TO MCs, due to the reduction in the fractional free volume of the core material. When the MCs were dispersed in an epoxy coating and applied on a metallic substrate, excellent healing capacities of up to 93% were observed for the 5% GNP samples, and 87% for the pure TO MC coatings. The coatings also exhibited excellent corrosion resistance for all samples up to 7 days, with the GNP samples offering a more strenuous path for the corrosive agents.

Preparation of food-grade EDC/NHS-crosslinked gelatin nanoparticles and their application for Pickering emulsion stabilization

Herein, a safe desolvation and crosslinking method was developed to prepare food-grade bovine bone gelatin (BBG) nanoparticles for Pickering emulsion stabilization. The nanoparticle-like structures were formed by adjusting pH 9.0 and adding ethanol, and then stable nanoparticles were formed by using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) as crosslinker. Compared with other pH (2.5, 5.0, 7.0, and 12.0), pH 9.0 was the appropriate pH to prepare BBG nanoparticles. Individual nanoparticles (6.50 nm in height), oligomeric nanoparticles (13.42-22.52 nm in height), and polymeric nanoparticles (obvious liquid-precipitate separation) were formed at EDC·HCl/NHS concentrations of 6, 9-12, and 15-20 mg/mL, respectively. The oligomeric nanoparticles induced the highest emulsion creaming stability. The emulsion creaming ability increased with the increase of BBG nanoparticle concentrations. Low NaCl concentration (e.g., 100 mmol/L) could increase the emulsion creaming stability. Finally, 4 °C was the best storage temperature for fish oil-loaded Pickering emulsions.

Chemical and Structural Engineering of Gelatin-Based Delivery Systems for Therapeutic Applications: A Review

As a biodegradable and biocompatible protein derived from collagen, gelatin has been extensively exploited as a fundamental component of biological scaffolds and drug delivery systems for precise medicine. The easily engineered gelatin holds great promise in formulating various delivery systems to protect and enhance the efficacy of drugs for improving the safety and effectiveness of numerous pharmaceuticals. The remarkable biocompatibility and adjustable mechanical properties of gelatin permit the construction of active 3D scaffolds to accelerate the regeneration of injured tissues and organs. In this Review, we delve into diverse strategies for fabricating and functionalizing gelatin-based structures, which are applicable to gene and drug delivery as well as tissue engineering. We emphasized the advantages of various gelatin derivatives, including methacryloyl gelatin, polyethylene glycol-modified gelatin, thiolated gelatin, and alendronate-modified gelatin. These derivatives exhibit excellent physicochemical and biological properties, allowing the fabrication of tailor-made structures for biomedical applications. Additionally, we explored the latest developments in the modulation of their physicochemical properties by combining additive materials and manufacturing platforms, outlining the design of multifunctional gelatin-based micro-, nano-, and macrostructures. While discussing the current limitations, we also addressed the challenges that need to be overcome for clinical translation, including high manufacturing costs, limited application scenarios, and potential immunogenicity. This Review provides insight into how the structural and chemical engineering of gelatin can be leveraged to pave the way for significant advancements in biomedical applications and the improvement of patient outcomes.

Effects of gelatin type and concentration on the preparation and properties of freeze-dried fish oil powders

The effects of gelatin type (porcine skin gelatin, PSG; bovine skin gelatin, BSG; fish gelatin, FG; or cold-water fish skin gelatin, CFG) and concentration on the preparation and properties of fish oil powders were investigated in this work. The oil powders were prepared using the combination method of gelatin-sodium hexametaphosphate complex coacervation with starch sodium octenyl succinate (SSOS)-aided freeze-drying. Compared with the other gelatins, CFG-with an unobvious isoelectric point, a lower molecular weight, more hydrogen bonds, and longer gel formation time-could not form complex coacervates, which are necessary to prepare oil powders. For oil powders obtained from the other gelatins, gelatin type and concentration did not have obvious effects on microscale morphologies; they did, however, have significant effects on physicochemical properties. The highest peroxide values of the oil powders were mainly dependent on the gelatins, expressed in the following manner: PSG (153 ± 5 - 168 ± 3 meq/Kg oil) < BSG (176 ± 5 - 188 ± 1 meq/Kg oil) < FG (196 ± 11 - 201 ± 22 meq/Kg oil). Acidic and neutral pH could not dissolve the complex coacervates. However, the oil powders could be quickly dissolved to form emulsion droplets in the gastric phase, and that SSOS increased coacervate stability and promoted oil digestion during the in vitro gastrointestinal process. In sum, this study contributes fundamental information to understanding the development of fish oil solid encapsulation preparations.

Gelatin-containing porous polycaprolactone PolyHIPEs as substrates for 3D breast cancer cell culture and vascular infiltration

Tumour survival and growth are reliant on angiogenesis, the formation of new blood vessels, to facilitate nutrient and waste exchange and, importantly, provide a route for metastasis from a primary to a secondary site. Whilst current models can ensure the transport and exchange of nutrients and waste via diffusion over distances greater than 200 μm, many lack sufficient vasculature capable of recapitulating the tumour microenvironment and, thus, metastasis. In this study, we utilise gelatin-containing polymerised high internal phase emulsion (polyHIPE) templated polycaprolactone-methacrylate (PCL-M) scaffolds to fabricate a composite material to support the 3D culture of MDA-MB-231 breast cancer cells and vascular ingrowth. Firstly, we investigated the effect of gelatin within the scaffolds on the mechanical and chemical properties using compression testing and FTIR spectroscopy, respectively. Initial in vitro assessment of cell metabolic activity and vascular endothelial growth factor expression demonstrated that gelatin-containing PCL-M polyHIPEs are capable of supporting 3D breast cancer cell growth. We then utilised the chick chorioallantoic membrane (CAM) assay to assess the angiogenic potential of cell-seeded gelatin-containing PCL-M polyHIPEs, and vascular ingrowth within cell-seeded, surfactant and gelatin-containing scaffolds was investigated via histological staining. Overall, our study proposes a promising composite material to fabricate a substrate to support the 3D culture of cancer cells and vascular ingrowth.

Collagen and gelatin: Structure, properties, and applications in food industry

Food-producing animals have the highest concentration of collagen in their extracellular matrix. Collagen and gelatin are widely used in food industry due to their specific structural, physicochemical, and biochemical properties, which enable them to improve health and nutritional value as well as to increase the stability, consistency, and elasticity of food products. This paper reviews the structural and functional properties including inherent self-assembly, gel forming, water-retaining, emulsifying, foaming, and thickening properties of collagen and gelatin. Then the colloid structures formed by collagen such as emulsions, films or coatings, and fibers are summarized. Finally, the potential applications of collagen and gelatin in muscle foods, dairy products, confectionary and dessert, and beverage products are also reviewed. The objective of this review is to provide the current market value, progress as well as applications of collagen and its derivatives in food industry.

Photothermal Conversion of Hydrogel-Based Biomaterial

Traditional energy from fossil fuels like petroleum and coal is limited and contributes to global environmental pollution and climate change. Developing sustainable and eco-friendly energy is crucial for addressing significant challenges such as climate change, energy dilemma and achieving the long-term development of human society. Biomass hydrogels, which are easily synthesized and modified, have diverse sources and can be designed for different applications. They are being extensively researched for their applications in artificial intelligence, flexible sensing, biomedicine, and food packaging. The article summarizes recent advances in the preparation and applications of biomass-based photothermal conversion hydrogels, discussing the light source, photothermal agents, matrix, and preparation methods in detail. It also explores the use of these hydrogels in seawater desalination, photothermal therapy, antibacterial agents, and light-activated materials, offering new ideas for developing sustainable, efficient, and advanced photothermal conversion biomass hydrogel materials. The article concludes with suggestions for future research, highlighting the challenges and prospects in this field and paving the way for developing of long-lasting, efficient energy materials.

Influence of gelatin type on physicochemical properties of electrospun nanofibers

This study explores the fabrication of nanofibers using different types of gelatins, including bovine, porcine, and fish gelatins. The gelatins exhibited distinct molecular weights and apparent viscosity values, leading to different entanglement behavior and nanofiber production. The electrospinning technique produced nanofibers with diameters from 47 to 274 nm. The electrospinning process induced conformational changes, reducing the overall crystallinity of the gelatin samples. However, porcine gelatin nanofibers exhibited enhanced molecular ordering. These findings highlight the potential of different gelatin types to produce nanofibers with distinct physicochemical properties. Overall, this study sheds light on the relationship between gelatin properties, electrospinning process conditions, and the resulting nanofiber characteristics, providing insights for tailored applications in various fields.

Surfactant-free gelatin-stabilised biodegradable polymerised high internal phase emulsions with macroporous structures

High internal phase emulsion (HIPE) templating is a well-established method for the generation of polymeric materials with high porosity (>74%) and degree of interconnectivity. The porosity and pore size can be altered by adjusting parameters during emulsification, which affects the properties of the resulting porous structure. However, there remain challenges for the fabrication of polyHIPEs, including typically small pore sizes (∼20-50 μm) and the use of surfactants, which can limit their use in biological applications. Here, we present the use of gelatin, a natural polymer, during the formation of polyHIPE structures, through the use of two biodegradable polymers, polycaprolactone-methacrylate (PCL-M) and polyglycerol sebacate-methacrylate (PGS-M). When gelatin is used as the internal phase, it is capable of stabilising emulsions without the need for an additional surfactant. Furthermore, by changing the concentration of gelatin within the internal phase, the pore size of the resulting polyHIPE can be tuned. 5% gelatin solution resulted in the largest mean pore size, increasing from 53 μm to 80 μm and 28 μm to 94 µm for PCL-M and PGS-M respectively. In addition, the inclusion of gelatin further increased the mechanical properties of the polyHIPEs and increased the period an emulsion could be stored before polymerisation. Our results demonstrate the potential to use gelatin for the fabrication of surfactant-free polyHIPEs with macroporous structures, with potential applications in tissue engineering, environmental and agricultural industries.

Improving the Stability of Water-in-Oil Emulsions with Medium Internal Phase by the Introduction of Gelatin

The water-in-oil (W/O) emulsion with a medium aqueous phase may be limited in food and cosmetics due to its poor stability and high cost. Herein, this work proposed a facile strategy to improve the W/O emulsion stability by introducing gelatin. The influence of different gelatin concentrations (0, 0.5%, 1.0%, 2.0%, and 4.0%) on the stability and properties of W/O emulsions was mainly investigated. Results showed that the obtained emulsions still belonged to W/O emulsions after adding gelatin to the aqueous phase. As the gelatin concentration increased (0~4.0%), the interfacial tension decreased, which is conducive to promoting the interface adsorption of polyglycerol polyricinoleate (PGPR). Furthermore, introducing gelatin also improved the water-holding capacity (WHC) (33.50~6.32%) and viscosity of W/O emulsions and reduced the droplet size (37.47~8.75 μm) of emulsions. The enhanced interfacial adsorption and aqueous gelation induced by gelatin addition promoted the formation of a tight overall emulsion network structure by the interaction between the interfacial adsorbed PGPR, as well as PGPR and gelatin in the aqueous phase. The enhancement of the overall network effectively improved the storage stability (35 d), thermal stability (20 min, 80 °C), and freeze-thaw stability (10 cycles) of emulsions, especially at 4.0% gelatin concentration. Hence, this study can provide guidance for the improvement and regulation of the stabilities of W/O emulsions.

Tween emulsifiers improved alginate-based dispersions and ionic crosslinked milli-sized capsules

The blending of surfactants might change the properties of alginate-based oil encapsulation preparations. Herein, the effects of Tween series (Tween 20, 40, 60, and 80) blending on the fish oil-encapsulated sodium alginate dispersions and calcium alginate capsules were studied. The results suggested Tween 80 showed better emulsifying properties than Span 80 for the alginate/surfactant emulsions. All the Tween series induced higher creaming stability than the sodium alginate-stabilized dispersion. Tween series blending did not change the sizes, decreased the water contents, and induced similar particle-like protrusions of calcium alginate capsules. Loading capacity and encapsulation efficiency of fish oil were dependent on the hydrophilic heads and fatty acid moieties of the Tween series. Tween series blending could increase the fish oil oxidative stability of the capsules. In the in vitro digestion process, Tween with saturated fatty acid moieties increased the free fatty acid release percentages. This work provided potential innovative processing technologies for improving the biological potency of fish oil.

A review on proteomic and genomic biomarkers for gelatin source authentication: Challenges and future outlook

Biomarkers are compounds that could be detected and used as indicators of normal and/or abnormal functioning of different biological systems, including animal tissues and food matrices. Gelatin products of animal origin, mainly bovine and porcine, are currently under scrutiny mainly due to the specific needs of some sectors of the population related to religious beliefs and their dietary prohibitions, as well as some potential health threats associated with these products. Thus, manufacturers are currently in need of a reliable, convenient, and easy procedure to discern and authenticate the origin of animal-based gelatins (bovine, porcine, chicken, or fish). This work aims to review current advances in the creation of reliable gelatin biomarkers for food authentication purposes based on proteomic and DNA biomarkers that could be applied in the food sector. Overall, the presence of specific proteins and peptides in gelatin can be chemically analysed (i.e., by chromatography, mass spectroscopy, electrophoresis, lateral flow devices, and enzyme-linked immunosorbent assay), and different polymerase chain reaction (PCR) methods have been applied for the detection of nucleic acid substances in gelatin. Altogether, despite the fact that numerous methods are currently being developed for the purpose of detecting gelatin biomarkers, their widespread application is highly dependent on the cost of the equipment and reagents as well as the ease of use of the various methods. Combining different methods and approaches targeting multiple biomarkers may be key for manufacturers to achieve reliable authentication of gelatin's origin.

Gelatin as a bioactive nanodelivery system for functional food applications

Gelatin has long been used as an encapsulant agent in the pharmaceutical and biomedical industries because of its low cost, wide availability, biocompatibility, and degradability. However, the exploitation of gelatin for nanodelivery application is not fully achieved in the functional food filed. In this review article, we highlight the latest work being performed for gelatin-based nanocarriers, including polyelectrolyte complexes, nanoemulsions, nanoliposomes, nanogels, and nanofibers. Specifically, we discuss the applications and challenges of these nanocarriers for stabilization and controlled release of bioactive compounds. To achieve better efficacy, gelatin is frequently used in combination with other biomaterials such as polysaccharides. The fabrication and synergistic effects of the newly developed gelatin composite nanocarriers are also present.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

pH-induced complex coacervation of fish gelatin and carboxylated chitosan: phase behavior and structural properties

The aim of this study was to investigate the phase behavior and structural properties of fish gelatin complex coacervation with carboxylated chitosan as a function of pH by varying the amount of carboxylated chitosan added (0-0.25%, w/v) while keeping the fish gelatin concentration constant at 0.667% (w/v). Zeta potential indicated that electrostatic interaction drove the complex coalescence of fish gelatin and carboxylated chitosan to form soluble or insoluble complexes. The turbidity of the fish gelatin-carboxylated chitosan complex system was greatest at a carboxylated chitosan concentration of 0.2%. UV and fluorescence spectroscopy indicated that the carboxylated chitosan changed the tertiary conformation of fish gelatin. Circular dichroism showed that complexation of fish gelatin with carboxylated chitosan resulted in a shift from the α-helix to the β-sheet structure of fish gelatin. In particular, at pH 5, the fish gelatin complexed with carboxylated chitosan had a disordered structure. X-ray diffraction and scanning electron microscopy of the composite coacervates both investigated that electrostatic interaction between the two replaced molecular interaction within the carboxylated chitosan to form a new lamellar porous structure. These findings may in future enable the use of fish gelatin-carboxylated chitosan complex systems in the design of new food matrices.

Curcumin-encapsulated hydrophilic gelatin nanoparticle to stabilize fish oil-loaded Pickering emulsion

Herein, pH-cycle method was explored to prepare curcumin-encapsulated hydrophilic bovine bone gelatin (BBG/Cur) nanoparticle and then the obtained nanoparticle was applied to stabilize fish oil-loaded Pickering emulsion. The nanoparticle had a high encapsulation efficiency (93.9 ± 0.5 %) and loading capacity (9.4 ± 0.1 %) for curcumin. The nanoparticle-stabilized emulsion had higher emulsifying activity index (25.1 ± 0.9 m²/g) and lower emulsifying stability index (161.5 ± 18.8 min) than BBG-stabilized emulsion. The pH affected the initial droplet sizes and creaming index values of the Pickering emulsions: pH 11.0 < pH 5.0 ≈ pH 7.0 ≈ pH 9.0 < pH 3.0. Curcumin provided obvious antioxidant effect for the emulsions, which was also dependent on pH. The work suggested pH-cycle method could be used to prepare hydrophobic antioxidant-encapsulated hydrophilic protein nanoparticle. It also provided basic information on the development of protein nanoparticles for Pickering emulsion stabilization.

Gelatin and Chitosan as Meat By-Products and Their Recent Applications

Meat by-products such as bones, skin, horns, hooves, feet, skull, etc., are produced from slaughtered mammals. Innovative solutions are very important to achieving sustainability and obtaining the added value of meat by-products with the least impact on the environment. Gelatin, which is obtained from products high in collagen, such as dried skin and bones, is used in food processing, and pharmaceuticals. Chitosan is derived from chitin and is well recognized as an edible polymer. It is a natural product that is non-toxic and environmentally friendly. Recently, chitosan has attracted researchers' interests due to its biological activities, including antimicrobial, antitumor, and antioxidant properties. In this review, article, we highlighted the recent available information on the application of gelatin and chitosan as antioxidants, antimicrobials, food edible coating, enzyme immobilization, biologically active compound encapsulation, water treatment, and cancer diagnosis.

The Structural and Functional Differences between Three Species of Fish Scale Gelatin and Pigskin Gelatin

In this paper, gelatin was extracted from the scales of Coregonus peled, Carp and Bighead carp by the acid method, and the structure and functional properties of the obtained scale gelatin and food-grade pigskin gelatin (FG) were compared. The results showed that all gelatins exhibited relatively high protein (86.81-93.61%), and low lipid (0.13-0.39%) and ash (0.37-1.99%) contents. FG had the highest gel strength, probably because of its high proline content (11.96%) and high average molecular weight distribution. Low β-antiparallel was beneficial to the stability of emulsion, which led FG to have the best emulsifying property. The high content of hydrophobic amino acids may be one of the reasons for the superior foaming property of Bighead carp scales gelatin (BCG). The gel strength of Carp scales gelatin (CG) and BCG, the ESI of Coregonus peled scales gelatin (CPG) and the foaming property of BCG indicate that fish gelatin has the potential to be used in food industry as a substitute for pig skin gelatin.

Effect of β-cyclodextrin deodorization on the volatile chemicals and functional properties of three types of gelatins

The exploration of deodorization is important for the application of gelatin in food industry. In this work, the effect of β-cyclodextrin (β-CD) deodorization on the volatile chemicals and functional properties of three types of gelatins (commercial porcine skin gelatin, cold water fish skin gelatin, and Chinese longsnout catfish skin gelatin) were studied. The results suggested the odors of commercial gelatins were significantly less than home-extracted gelatins. The β-CD deodorization efficiency was dependent on both β-CD concentration and volatile chemical. (E)-2-Octenal (C8H14O), 1-octen-3-ol (C8H16O), 2-pentyl-furan (C9H14O), and hentriacontane (C17H36) could be deodorized at low β-CD concentration (even at 2 mg/mL). The best β-CD deodorization concentration for 66.7 mg/mL of Chinese longsnout catfish skin gelatin was 30 mg/mL. β-CD addition could not change the gel forming ability and emulsion activity of gelatins, whereas it had different and concentration-dependent effects on the emulsion stability of gelatins. β-CD addition had no obvious effects on the droplet sizes, droplet coalescence and liquid-gel transition behaviors, but had different effects on the creaming of the emulsions stabilized by three types of gelatins. The encapsulation of β-carotene did not significantly change the droplet trimodal size distribution and liquid-gel transition of fish oil-loaded emulsions. However, β-carotene might delay the droplet coalescence. The creaming stability of β-carotene/fish oil-loaded gelatin/β-CD-stabilized emulsions was dependent on the gelatins, β-CD, and β-carotene. Finally, the β-carotene retention in the emulsions was dependent not on β-CD addition but on the nature of the gelatins. These results provided useful information to understand the molecular deodorization behaviors and explore the deodorization of emulsifiers for food emulsions.

Effect of extraction methods on the properties of tilapia scale gelatins

Three types of tilapia scale gelatins (hot water-pretreated gelatin, HWG; acetic acid-pretreated gelatin, AAG; and pepsin enzyme-pretreated gelatin, PEG) were extracted and their gel strength, foaming properties, and emulsifying properties were analyzed. They had different gel strength values: AAG (370 ± 10 g Bloom) > HWG (320 ± 10 g Bloom) > PEG (280 ± 10 g Bloom). The creaming index values of tilapia scale gelatin-stabilized fish oil-loaded emulsions were dependent on gelatin type (HWG ≈ AAG > PEG) at low gelatin concentration (2 mg/mL), whereas they were similar and low (8-10 %) at high gelatin concentration (10 mg/mL). Extraction methods had no consistently significant effects on the gelatin foaming properties. In summary, tilapia scale gelatins had better gel strength and foaming properties and similar or even better emulsifying properties than mammalian gelatins. Therefore, tilapia scales could be a potential source of gelatins to replace mammalian gelatins.