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PLA (polylactic acid) is one of the three major biopolymers available on the market for food packaging, which is both bio-based and biodegradable. However, its performance as a barrier to gases remains too weak to be used for most types of food, particularly oxygen-sensitive foods. A surface treatment, such as coating, is a potential route for improving the barrier properties and/or providing bioactive properties such as antioxidants. Gelatin-based coating is a biodegradable and food-contact-friendly solution for improving PLA properties. The initial adhesion of gelatin to the film is successful, both over time and during production, however, the coating often delaminates. Corona processing (cold air plasma) is a new tool that requires low energy and no solvents or chemicals. It has been recently applied to the food industry to modify surface properties and has the potential to significantly improve gelatin crosslinking. The effect of this process on the functional properties of the coating, and the integrity of the incorporated active compounds were investigated. Two coatings have been studied, a control fish gelatin-glycerol, and an active one containing gallic acid (GA) as a natural antioxidant. Three powers of the corona process were applied on wet coatings. In the test conditions, there were no improvements in the gelatin crosslinking, but the corona did not cause any structural changes. However, when the corona and gallic acid were combined, the oxygen permeability was significantly reduced, while free radical scavenging, reduction, and chelating properties remained unaffected or slightly improved. [ABSTRACT FROM AUTHOR]

Genipin crosslinked composite blends of fish gelatin/kappa-carrageenan (fG/κC) with different concentrations of graphene oxide (GO) for osteochondral substitutes were prepared by a simple solution-blending method. The resulting structures were examined by micro-computer tomography, swelling studies, enzymatic degradations, compressions tests, MTT, LDH, and LIVE/DEAD assays. The derived findings revealed that genipin crosslinked fG/κC blends reinforced with GO have a homogenous morphology with ideal pore dimensions of 200–500 µm for bones alternative. GO additivation with a concentration above 1.25% increased the blends' fluid absorption. The full degradation of the blends occurs in 10 days and the gel fraction stability increases with GO concentration. The blend compression modules decrease at first until fG/κC GO3, which has the least elastic behavior, then by raising the GO concentration the blends start to regain elasticity. The MC3T3-E1 cell viability reveals less viable cells with the increase of GO concentration. The LDH together with the LIVE/DEAD assays reports a high concentration of live and healthy cells in all types of composite blends and very few dead cells at the higher GO content. [ABSTRACT FROM AUTHOR]

In this study, the yield of gelatin extraction from fish waste was optimized using response surface method. The highest yield was obtained with 0.8% citric acid concentration at 72.95°C for 58 minutes. Then, fish gelatin was modified using ultraviolet radiation to overcome fish gelatin defects including unsuitable rheological properties and low thermo-stability. UV irradiation can create crosslinks via alkyl or phenyl groups of the proteins. The modified sample also showed the highest melting point due to the creation of cross-links and improved emulsification and foaming properties of fish gelatin through structural modification and increased surface hydrophobicity of gelatin. [ABSTRACT FROM AUTHOR]

This study aims to prepare fish gelatin nanofibers extracted from fish waste by using electrospinning method and its encapsulation with fucoxanthin extracted from macroalgae Sargassum angustifolium. Four concentrations of gelatin and two concentrations of fucoxanthin were used under different voltage for preparing the nanofibers. The optimal conditions for producing the nanofibers were considered as 30%, 10 cm, 12 kV, and 5% for fish gelatin concentration, distance, voltage, and fucoxanthin, respectively. The average thickness of nanofibers was estimated 198 ± 0.073 nm. The FTIR results confirmed the presence of functional groups between fucoxanthin and gelatin. The loading efficiency of fucoxanthin in nanofibers and the free radical scavenging of DPPH were calculated 91% and 62%, respectively. Further, these nanofibers showed the antibacterial properties against bacteria. Based on the results, the fish gelatin nanofibers containing fucoxanthin can be proposed as a suitable coating for using in the food packaging industry. [ABSTRACT FROM AUTHOR]

Moisture adsorption and desorption isotherms of gelatin extracted from whitefish skin powder (FSGP) at different temperatures across a wide range of water activity were determined along with their thermodynamic properties. Nine mathematical models were utilized for fitting the experimental data and simulating the adsorption and desorption behavior. The thermodynamic properties were determined and fitted to the experimental data. The results showed that Peleg and GAB models were the best fit for FSGP. The energies involved in the adsorption and desorption process of FSGP indicated a stronger dependence on equilibrium moisture content (Xe). When Xe decreased, there was a consistent trend of increasing thermodynamic properties. Both the moisture adsorption and desorption behaviors of FSGP were, therefore, non-spontaneous processes. Linear correlations between the changes in enthalpy and entropy for adsorption and desorption were observed, indicating the presence of enthalpy–entropy compensation for FSGP. For preserving FSGP quality, it should be stored with Xw ≤ 8 (gw/gdm, d.b.) at temperatures below 53 °C and an RH of 50% to avoid it becoming rubbery. These findings are crucial for providing insight into the optimal drying and storage conditions.

Abstract Background Wound healing has become a worldwide healthcare issue. Attempts in the area focus on developing patches with the capabilities of avoiding wound infection, promoting tissue remolding, and reporting treatment status that are of great value for wound treatment. Results In this paper, we present a novel inverse opal film (IOF) patch based on a photo-crosslinking fish gelatin hydrogel with the desired features for wound healing and dynamic monitoring. The film with vibrant structure colors was constructed by using the mixture of fish gelatin methacryloyl, chitosan, and polyacrylic acid (PAA) to replicate colloidal crystal templates. As the structures of these natural biomolecules are well-retained during the fabrication, the resultant IOF was with brilliant biocompatibility, low immunogenicity, antibacterial property, as well as with the functions of promoting tissue growth and wound healing. In addition, the IOF presented interconnected nanopores and high specific surface areas for vascular endothelial growth factor loading, which could further improve its angiogenesis capability. More attractively, as the pH-responsive PAA was incorporated, the IOF patch could report the wound healing status through its real-time structural colors or reflectance spectra. Conclusions These features implied the practical value of the multifunctional fish gelatin hydrogel IOFs in clinical wound management. Graphical Abstract

Active films are the new generation of packaging in the food industry that can maintain and develop the shelf life of food products. The aim of this study was to fabricate and characterize an antioxidant film using fish gelatin and Coleus scutellarioides extract (CSE). The CSE was added to the gelatin film solutions in three levels (10, 20, and 30 mL from the extract to 100 mL film solution). The results showed that increasing the extract level increased the thickness of films, and water vapor permeability decreased significantly (p < 0.05). The addition of CSE had no significant effect on the moisture content of films. Based on SEM images and FTIR spectra, the fabricated active films have a uniform and uneven structure and fracture were observed in the film structure at high levels of CSE. Chemical bonds were established between the protein-polymer and the phenolic compounds of extract. The incorporation of the CSE also increased the total phenol content, and the antioxidant activity of films and the highest amounts of them were observed in the sample containing the highest level of extract (28.73 mg GA/g of film and 83.24%, respectively). In summary, fish gelatin films containing CSE have the potential to be used as active packaging to extend the shelf life of food products.

Ice cream is a frozen dairy product that includes healthy and nutritious aspects. To improve the value of the health benefits, it is necessary to develop functional ice cream products. One such addition is horn plantain bananas, which have the benefit of having a high dietary fiber and pectin content. In order to make ice cream, gelatin must be used as a stabilizer. The increase of non-halal gelatin has led to improvements in the production of halal gelatin derived from fish. This study was performed to evaluate the effect of adding fish gelatin to the characteristics of plantain banana (Musa paradisiaca fa. Corniculata)-based ice cream. This study used a pre-experimental design with a fully randomized design and one component, the addition of varying quantities of fish gelatin (A1: 0%, A2: 0.25%, and A3: 0.5%) with three replicates. The characteristics (taste, fragrance, texture, and colour), melting time, and overrun were evaluated. The Duncan Multiple Range Test as post-hoc teste was used to continue ANOVA-based data analysis. The results demonstrated that the inclusion of fish gelatin at various levels did not significantly alter the degree of preference for colour, fragrance, flavour, or overrun. Texture and melting time were different (p

The objective of this study was to evaluate the effects of microwave processing technology (MPT, 240–800 W, 1 and 4 min) on the functional and structural properties of fish gelatin (FG). It showed that MPT could increase gel strength and texture properties of FG, especially for 240 W. MPT greatly increased emulsifying activity index (EAI) of FG, but decreased its emulsion stability index (ESI). Rheology results showed that MPT increased viscosity of FG, but decreased gelation times. Intrinsic fluorescence and Fourier transform infrared (FTIR) spectroscopy results indicated that MPT could unfold gelatin, contributing to the formation of H‐bonds. Scanning electron microscopy (SEM) analysis revealed that low power and short time of MPT‐treated gelatin gels had much more dense and less voids. This work provided guidance for the applications of MPT to improve the functional properties of FG, and the results show that MPT‐treated FG can replace mammalian gelatin and meet the religious requirement. [ABSTRACT FROM AUTHOR]

The effects of ultrasound-assisted glycosylation (UG) with glucose (GLU) on the emulsifying properties, foaming properties, gelling properties, and structural properties of fish gelatin (FG) were investigated. It was shown that UG with high power and a long duration facilitated the Maillard reaction through the reduction of the free amino acid contents. UG significantly improved the emulsifying ability index and foaming capacity of FG whilst decreasing the gel strength. Rheological analysis showed that UG modification prolonged the gelling time by hindering the triple-helix formation and decreasing the apparent viscosity of the gelatin solution. Structural analysis showed that UG treatment changed the secondary structure of the gelatin molecule by the formation of Millard reaction products (MRPs). Moreover, the UG treatment generally decreased the bound water contents of the gelatin gels with an increase in free water. [ABSTRACT FROM AUTHOR]

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The field of tissue engineering is constantly evolving due to the fabrication of novel platforms that promise to stimulate tissue regeneration in the scenario of accidents. Here, we describe the fabrication of fibrous nanostructured substrates based on fish gelatin (FG) and enriched with graphene oxide (GO) and magnetic nanoparticles (MNPs) and demonstrate its biological properties in terms of cell viability and proliferation, cell adhesion, and differentiation. For this purpose, electrospun fibers were fabricated using aqueous precursors containing either only GO and only MNP nanospecies, or both of them within a fish gelatin solution. The obtained materials were investigated in terms of morphology, aqueous media affinity, tensile elasticity, and structural characteristics. The biological evaluation was assessed against adipose-derived stem cells by MTT, LDH, Live/Dead assay, cytoskeleton investigation, and neuronal trans-differentiation. The results indicate an overall good interaction and show that these materials offer a biofriendly environment. A higher concentration of both nanospecies types induced some toxic effects, thus 0.5% GO, MNPs, and GO/MNPs turned out to be the most suitable option for biological testing. Moreover, a successful neuronal differentiation has been shown on these materials, where cells presented a typical neuronal phenotype. This study demonstrates the potential of this scaffold to be further used in tissue engineering applications. [ABSTRACT FROM AUTHOR]

Different pretreatment methods were applied on Rhinobatos cemiculus skin, and their effect on the physicochemical properties of the extracted gelatin was investigated. Prior to extracting gelatin, the skin was pretreated using three methods: bleaching (RCG-BT), ultrasound (RCG-UST) and microwave (RCG-MT). The properties of the resulting gelatins were compared to those of the untreated-skin gelatin (RCG-WT). The pretreatment of R. cemiculus skin was found to differently affect the isoelectric point (pHi), color, structure, thermal stability as well as foam/emulsion-forming capacities of the derived gelatins. In fact, the SDS-PAGE profile revealed the presence of the three gelatin characteristic chains (β and α1/α2) as predominant components in all gelatins with a slight decrease in bands intensity for gelatin exposed to microwave radiation. Based on FTIR analysis, gelatin characteristic bands were found in all gelatins with a slight shift for RCG-MT proving its structural re-arrangements confirmed by X-ray diffraction. Furthermore, among the applied pretreatments on RCG, ultrasound and bleaching were found to be the best techniques giving the most thermally stable gelatins. Additionally, functional properties related to gelatin derived from ultrasound pretreated skin were found to exhibit the highest foam expansion and emulsion activity. [ABSTRACT FROM AUTHOR]

Red chili is a climacteric fruit that still undergoes respiration after harvest. During storage, it is susceptible to mechanical, physical, and physiological damage and decay incidence, therefore a method is needed to protect it so that the quality losses can be minimized. One way this can be achieved is by applying edible coatings that can be made from hydrocolloids, lipids, or composites of both, in addition to antimicrobial agents that can also be added to inhibit microbial growth. In this study, we detail the application of an edible coating made of gelatin composite from tilapia fish skin, which has a transparent color and good barrier properties against O2, CO2, and lipids. To increase its physicochemical and functional qualities, it must be modified by adding composite elements such as pectin as well as hydrophobic ingredients such as garlic essential oil. This study was conducted to determine the effect of a gelatin–pectin composite edible coating (75:25, 50:50, 25:75), which was incorporated with garlic essential oil (2% and 3%) on the physicochemical properties of red chili at room temperature (±29 °C), RH ± 69%) for 14 days. The best treatment was the 50–50% pectin–gelatin composite, which was incorporated with garlic essential oil with a concentration of 2 and 3%. This treatment provided a protective effect against changes in several physicochemical properties: inhibiting weight loss of 36.36 and 37.03%, softening of texture by 0.547 and 0.539 kg/84 mm2, maintaining acidity of 0.0087 and 0.0081%, maintaining vitamin C content of 2.237 and 2.349 mg/gr, anti-oxidant activity (IC50) 546.587 and 524.907; it also provided a protective effect on chili colors changing to red, and retains better total dissolved solid values. [ABSTRACT FROM AUTHOR]

Bioactive peptides showing Angiotensin-I-Converting Enzyme inhibitory (ACEi) activity can control blood pressure. They can be produced from various protein sources, including fish gelatin. This article provides a systematic review and metaanalysis on gelatin extraction, conditions of enzymatic hydrolysis, characteristics of ACEi peptides, and effect of hydrolysis procedure on ACEi peptides. Fish gelatin preparation uses various solutions such as acids, bases and distilled water. Enzymatic hydrolysis is carried out with an E/S ratio of 0.2 7% and temperature of 28.9 oC (using bromelain) and 60.6 oC (using Alcalase). Level of pH in hydrolysis also varied greatly, from 2 (using Pepsin) to 10 (using Purafect enzyme). The molecular weight of fish gelatin ACEi peptides ranged from 186-829 Da and the sequence of peptides was dominated by hydrophobic and aliphatic amino acids. Based on a meta-analysis, hydrolysis using enzyme combination resulted in more satisfying product than a single enzyme, represented with a combined effect size value of 0.593. [ABSTRACT FROM AUTHOR]

Fish gelatin-agar edible films have potential for sustainable food packaging, but their limitations particularly water sensitivity require improvement. In this research, the effects of radiation from gamma rays at rates ranging from 0 to 40 kGy on the films' mechanical characteristics, microstructure, color, opacity, and water resistance were examined. Overall, gamma irradiation at doses of up to 30 kGy substantially improved the water resistance of the gelatin-agar film, as demonstrated by decreased water solubility, water absorption, and film vapor permeability. This could be due to crosslinking within the biopolymer network. However, at doses of 40 kGy, potential chain scission in the film's polymeric structure might occur, which counteracts further improvement and consequently starts degrading its water resistance. Similarly, the improvement of film's tensile strength and modulus of elasticity peaked at an optimal dose of 30 kGy, and then decreased at higher doses, while the film's elongation at break remained unaffected. FTIR and SEM analysis supported changes in functional group and structural morphology in these observations. Although irradiation caused some yellowing, an optimal dose range (at around 20–30 kGy) was identified to achieve improved functionality without degrading film integrity. These findings highlight the potential of gamma irradiation as a viable technique for modifying fish gelatin-agar films for enhanced performance in food packaging applications. • Gamma irradiation (up to 30 kGy) significantly improved fish gelatin-agar film's water resistance. • Improved tensile strength & elasticity observed at 30 kGy, suggesting optimal crosslinking within the film. • Higher irradiation (40 kGy) led to decreased film performance, indicating potential chain scission. • FTIR & SEM analysis supported structural changes influencing film properties. • Optimal irradiation dose (20–30 kGy) achieved improved function without compromising film integrity. [ABSTRACT FROM AUTHOR]

The significant concerns associated with the widespread use of petroleum-based plastic materials have prompted substantial research on and development of active food packaging materials. Even though fish gelatin-based films are appealing as active food packaging materials, they present practical production challenges. Therefore, this study aimed to develop an edible film using Ficus carica L. leaf extract (FLE), as it is affordable, accessible, and has superoxide anion radical scavenging action. This edible film was produced by adding FLE to mackerel skin gelatin at varied concentrations (2.5–10% w/w). The results showed that adding FLE to gelatin films significantly affected the tensile strength (TS), elongation at break (EAB), transmittance and transparency, solubility, water vapor permeability (WVP), antioxidant activity, and antibacterial activity. Among all the samples, the most promising result was obtained for the edible film with FLE 10%, resulting in TS, EAB, solubility, WVP, antioxidant activity, and antibacterial activity against S. aureus and E. coli results of 2.74 MPa, 372.82%, 36.20%, 3.96 × 10−11 g/msPa, 45.49%, 27.27 mm, and 25.10 mm, respectively. The study’s overall findings showed that fish gelatin-based films incorporated with FLE are promising eco-friendly, biodegradable, and sustainable active packaging materials.

Chondroitin sulfate (ChS), chitosan (Chi), and fish gelatin (FG), which are byproducts of a fish-treatment small enterprise, were incorporated with glycerol (Gly) to obtain dense hydrogel membranes with reduced brittleness, candidates for dressing in wound healing applications. The mechanical properties of all samples were studied via Dynamic Mechanical Analysis (DMA) and tensile tests while their internal structure was characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD) instruments. Their surface morphology was analyzed by ThermoGravimetric Analysis (TGA) method, while their water permeability was estimated via Water Vapor Transmission Rate (WVTR) measurements. Wettability and degradation rate measurements were also carried out. Characterization results indicated that secondary interactions between the natural polymers and the plasticizer create the hydrogel membranes. The samples were amorphous due to the high concentration of plasticizer and the amorphous nature of the natural polymers. The integration of ChS led to decreased decomposition temperature in comparison with the glycerol-free sample, and all the materials had dense structures. Finally, the in vitro endothelial cell attachment studies indicate that the hydrogel membranes successfully support the attachment and survival of primary on the hydrogel membranes and could be appropriate for external application in wound healing applications as dressings.

Phosphorylated fish gelatin (PFG) exhibited preferable physical and chemical properties than fish gelatin (FG) in our previous study. To investigate the application values of PFG, the effects of different ratios (2:1, 1:1 and 1:2) of FG(PFG)/κ carrageenan (κC) on the quality of jelly gels (JGs) were investigated. The sensory quality of PFG:κC (1:2)/FG:κC (1:2) was found to be superior based on sensory evaluations, which was also verified with the results for texture, rheology, etc. Moreover, the structural changes in JGs were related to the introduction of phosphoric acid groups into the molecular chain of gelatin and the protein–polysaccharide interactions. According to the storage results, PFG jelly had better storage quality, higher hardness and chewiness values than those of FG jelly. High-throughput sequencing of JG microbial analysis showed that the addition of PFG changed the amount of microorganisms, microbial species abundance and the microbial composition of JGs, which were also closely related to the storage quality of JGs. In conclusion, the applications of PFG have promising potential to improve the quality of confectionery.

In order to explore the effect of heating method and heating time on physicochemical properties of fish gelatin, the protein composition, viscosity, rheological properties and thermal stability of heated gelatin solutions, and the gel strength, texture profile analysis (TPA) parameters and microstructure of gelatin gels were analyzed and compared. The results showed that the viscosity, rheological properties and thermal stability of fish gelatin solutions decreased significantly with the increase of heating time, while the change extents of these properties in the intermittent heated gelatin were less than those in the continuous heated gelatin. When gelatin was heated for 48 h continuously, the β band disappeared in the electrophoresis pattern, and the α1 and α2 subunits degraded obviously after being heated for 96 h. When gelatin was heated for 96 h intermittently, the β band disappeared. The gel strength and TPA parameters of the gel prepared by fish gelatin gradually decreased with the increase of heating time, whereas the gel properties of the intermittent heated gelatin were superior to those of the continuous heated gelatin. Scanning electron microscope results showed that the surfaces of continuous heated gels were smooth and flat, while the structure of gel prepared by intermittent heated gelatin was rougher and more porous. The results suggested that intermittent heating and the heating less than 12 h could reduce the heat degradation of gelatin.

The poor water solubility, bioavailability and stability of bioactive compounds have become the bottleneck restricting their wide application, thus developing a functional carrier to realize the efficient encapsulation and activity improvement of active hydrophobic substances has become a research hotspot. In this work, a functional glycosylated fish gelatin (called FG-COS conjugates) carrier based on fish gelatin (FG) and chitooligosaccharide (COS) via Maillard reaction was developed. The functional carrier exhibited good antioxidant activity and high encapsulation of curcumin (Cur). Enhanced antioxidant effect of Cur loaded in FG-COS conjugates (called FG–COS–Cur nanoparticles) was achieved, showing remarkable UV protection on Cur and enhanced intracellular antioxidant activity of FG–COS–Cur nanoparticles. Remarkably, FG–COS–Cur nanoparticles increased the cell viability of H2O2-induced oxidative damage Caco-2 cells, drastically reduced the levels of reactive oxygen species (ROS) and lactate dehydrogenase (LDH), and significantly increased intracellular antioxidant enzyme activities, which all exhibited a dose-response relationship. These findings suggested that the FG-COS conjugates with intrinsic antioxidant activity could effectively encapsulate Cur and improved bioavailability for hydrophobic active molecules in functional food field.

The Fish Gelatin (FG), a good alternative for unhealthy and limited socio-cultural mammalian gelatin appears to possess endogenous structural limitations. The goal of this work was to use enzymatic crosslinking to modify cold-water Fish Gelatin (FG) with Beet Pectin. Reaction conditions were optimized by a single factorial experiment and covalent crosslinking was measured by ultraviolet (UV)-Vis spectroscopy at 340 nm to indicate Horseradish Peroxidase (HRP) catalyzes Beet Pectin (BP). At 50 °C for 4 h, the highest weight ratio of heterologous adducts between FG-BP was 1:3, with HRP and Hydrogen peroxide (H2O2) of 2 µg/mL and 0.067%, (v/v), respectively. Intermolecular cross-linking was found between treated samples using ATR-FTIR and Sodium Dodecyl Sulphur and Polyacrylamide Gel Electrophoresis (SDS-PAGE). The heterologous product, control FG, and BP as well as a mixture of untreated FG-BP had a β-sheet of 41.14%, 39.65%, 39.9%, and 40.0%, respectively. The maximum reduction in elution was obtained in heterogeneous FG-BP complex. Furthermore, a schematic mechanism for Cold-water Fish Gelatin and Beet Pectin was proposed. Overall, peroxidase crosslinked BP was able to modify cold-water Fish Gelatin. The use of Horseradish peroxidase on Fish Gelatin could provide a practical way of building the FG-BP complex as a basis for understanding the FG functionalities comprehensively.

Bacterial nanocellulose (BNC) has received great attention for application as an artificial blood vessel material. However, many results showed that pristine BNC could not perfectly meet all the demands of blood vessels, especially for rapid endothelialization. In order to improve the properties of small-caliber vessels, different concentrations of fish gelatin (Gel) were deposited into the 3D network tubes and their properties were explored. The BNC/Gel composite tubes were treated with glutaraldehyde to crosslink BNC and fish gelatin. Compared with pristine BNC tubes, the BNC/Gel tubes had a certain improvement in mechanical properties. In vitro cell culture demonstrated that the human endothelial cells (HUVECs) and human smooth muscle cells (HSMCs) planted on the internal walls of BNC/Gel tubes showed better adhesion, higher proliferation and differentiation potential, and a better anticoagulation property, as compared to the cells cultured on pristine BNC tubes. Whole-blood coagulation experiments showed that the BNC/Gel tube had better properties than the BNC tube, and the hemolysis rate of all samples was less than 1.0%, satisfying the international standards for medical materials. An increase in the content of fish gelatin also increased the mechanical properties and the biocompatibility of small-caliber vessels. Considering the properties of BNC/Gel tubes, 1.0 wt/v% was selected as the most appropriate concentration of fish gelatin for a composite. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of tannic acid (TA) and caffeic acid (CA) as cross-linking agents on the physicochemical and mechanical properties of cold-water fish gelatin films. TA and CA (1%, 3%, and 5% of dried gelatin) were incorporated into the fish gelatin film solutions, and film samples were prepared using the solvent casting method. The gelatin film without phenolic acids was considered as the control sample. The results demonstrated that establishing cross-linking bonds between gelatin polymer and phenolic acids improved the film stability, and water solubility decreased from ~ 100 to ~ 40%. The lowest amount of oxygen permeability and the highest darkness were observed in the films containing the highest levels of phenolic acids. The incorporation of TA and CA into gelatin films also increased mechanical strength from ~ 28 to ~ 50 MPa. In conclusion, these results indicated that fish gelatin films cross-linked by two natural cross-linking agents (CA and TA) might be used as edible films and biomaterials, and TA is a more effective phenolic compound than CA. [ABSTRACT FROM AUTHOR]

The ricotta cheese undergoes early microbiological spoilage and high moisture loss that leads to brittle texture. The development of edible films based on active biomaterials plays an important role in the cheese industry. Thus, gelatin was extracted from the grey triggerfish (Balistes capriscus) co-product. The gelatin films were prepared and enriched with 5, 10 and 20 µg/ml of different solvent extracts from Moringa oleifera leaves. As compared to the control film, the lightness (L*) and redness (a*) of the enriched films decreased slightly, while their yellowness (b*) increased as the level of enrichment increased. No significant difference (p > 0.05) was measured in the thickness, tensile strength and elongation at break of the enriched films. As compared to the control geltin-based film, the film enriched with 20 µg/ml of ethanolic extract (F-MOE) showed 35% reduction in water vapor permeability, and then was chosen to wrapp cheese. Interestingly, after 6 days of storage, the F-MOE-wrapped ricotta cheese showed a significant reduction (p ≤ 0.05) in weight loss, approximately 34% compared to the unwrapped cheese. Furthermore, the F-MOE-wrapped cheese showed the lowest changes in pH, color and texture parameters, as well as the lowest levels of lipid peroxidation (0.90 ± 0.03 mg MDA/kg cheese), and yeasts and molds (2.78 ± 0.14 log CFU/g cheese), which could be explained by the phenolics incorporated into the film. The film made from grey triggerfish gelatin and enriched with M. oleifera ethanolic extract could be used to reduce microbiological spoilage and preserved the physical quality of ricotta cheese, which were economically important parameters. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of lactic acid (LA), citric acid (CA), and malic acid (MA) varying in concentration (0.5–2.0% w/w) on the rheological properties of fish gelatin (1.5–6.67% w/w) obtained from the skin of tilapia (Oreochromis mossambicus). The addition of LA, CA, or MA in gelatin dispersions significantly (p < 0.05) weakened their gel strengths, leading to a 14.3–62.2 reduction in gel strength. The gel strength, elastic (G′), and viscous (G″) moduli, as well as the gelling (TG) and melting (TM) temperatures of gelatin dispersions decreased with an increased level of acid added, implying the weakening effects of these acids on junction zones of the gelatin network in aqueous media. The addition of LA had less effect on these rheological properties of gelatin dispersions as compared to that of MA and CA, which were consistent with their effects on the pH of gelatin dispersions. Moreover, the reductions of TG and TM for gelatin dispersions with a higher gelatin concentration (e.g., 6.67% gelatin with 0.5% LA, TG dropped 0.4 °C) due to the addition of LA, CA, or MA were less pronounced compared to those with a lower gelatin content (e.g., 2% gelatin with 0.5% LA, TG dropped 7.1 °C), likely attributing to the stronger buffering effect of the high gelatin dispersion and less percentage reduction in the junction zones in the dispersion due to the addition of an acid. Incorporation of the effects of acids on the linear relationships (R2 = 0.9959–0.9999) between the square of gelatin concentrations and G′ or G″ could make it possible to develop a model to predict G′, G″, phase transition temperatures of gelatin dispersions containing different amounts of gelatin and acid (within the tested range) in the future. [ABSTRACT FROM AUTHOR]

Microneedles are demonstrated as an effective strategy for chronic wound treatment. Great endeavors are devoted to developing microneedles with natural compositions and potent functions to promote therapeutic effects for wound healing. Herein, a novel graphene oxide-integrated methacrylated fish gelatin (GO-FGelMA) microneedle patch encapsulated with bacitracin and vascular endothelial growth factor (VEGF) is developed for chronic wound management. As the natural components and porous structures of FGelMA, the fabricated microneedle patches display satisfactory biocompatibility and drug-loading ability. Owing to the integration of graphene oxide, the microneedle patches can realize promoted drug release via near-infrared (NIR) irradiation. Besides, the encapsulated bacitracin and VEGF endow the microneedle patches with the ability to inhibit bacterial growth and promote angiogenesis. It is demonstrated that the GO-FGelMA microneedle patches with efficient drug release exert a positive influence on the wound healing process through reduced inflammation, enhanced wound closure, and improved tissue regeneration. Thus, it is believed that the proposed drugs-loaded GO-FGelMA microneedle patches will hold great potential in future chronic wound treatment., (© 2024 Wiley‐VCH GmbH.)

This study aimed to investigate the effects of galacto-oligogalactose (GOS) glycosylation on the structural and functional properties of fish gelatin (FG). Results showed that with the increase of glycosylation time, grafting degree and browning increased, and new protein bands with increased molecular weight were observed by SDS-PAGE. Structural analysis showed that glycosylation reduced intrinsic fluorescence intensity and increased surface hydrophobicity of FG. FTIR analysis showed α-helix content decreased while random coil content increased in glycosylated FG. Emulsion activity index and emulsion stability index along with foam activity and foam stability were significantly elevated in GOS-4 and GOS-8, but FG glycosylated longer than 12 h exhibited less pronounced improvement. Glycosylated FG showed lower gel strength than control. The results indicate that moderate glycosylation could be applied to improve interfacial properties of FG.

Mycosporine-like amino acids (MAAs) are ultraviolet-absorbing compounds and have antioxidant functions. In this paper, MAAs were added into fish gelatin/sodium alginate films as an anti-ultraviolet additive. The effects of 0–5% MAAs (w/w, MAAs/fish gelatin) on the physical properties, antioxidant properties, antibacterial properties and anti-ultraviolet properties of fish gelatin/sodium alginate films were investigated. The results suggest that the content of the MAAs influenced the mechanical properties. The water content, swelling and water vapor permeability of the films were not altered with the addition of MAAs. In addition, the composite films showed effective antioxidant activity and antimicrobial activity. The incorporation of MAAs significantly improved the DPPH radical scavenging activity of the films from 35.77% to 46.61%. Moreover, the block ultraviolet rays' ability was also greatly improved when the film mixed with the MAAs and when the value of the light transmission was 0.6% at 350 nm. Compared with the pure composite film, the growth of E. coli covered by the composite film with 3.75% and 5% MAAs exhibited the best survival rate. These results reveal that MAAs are a good film-forming substrate, and MAAs have good potential to prepare anti-ultraviolet active films and antioxidant active films for applications. Overall, this project provides a theoretical basis for the study of active composite films with anti-ultraviolet activities, and it provides new ideas for the application of MAAs. [ABSTRACT FROM AUTHOR]

Background: Wound healing has become a worldwide healthcare issue. Attempts in the area focus on developing patches with the capabilities of avoiding wound infection, promoting tissue remolding, and reporting treatment status that are of great value for wound treatment. Results: In this paper, we present a novel inverse opal film (IOF) patch based on a photo-crosslinking fish gelatin hydrogel with the desired features for wound healing and dynamic monitoring. The film with vibrant structure colors was constructed by using the mixture of fish gelatin methacryloyl, chitosan, and polyacrylic acid (PAA) to replicate colloidal crystal templates. As the structures of these natural biomolecules are well-retained during the fabrication, the resultant IOF was with brilliant biocompatibility, low immunogenicity, antibacterial property, as well as with the functions of promoting tissue growth and wound healing. In addition, the IOF presented interconnected nanopores and high specific surface areas for vascular endothelial growth factor loading, which could further improve its angiogenesis capability. More attractively, as the pH-responsive PAA was incorporated, the IOF patch could report the wound healing status through its real-time structural colors or reflectance spectra. Conclusions: These features implied the practical value of the multifunctional fish gelatin hydrogel IOFs in clinical wound management. [ABSTRACT FROM AUTHOR]

In this study, gelatin was extracted from the by-product of Scomberoides commersonnianus, and after evaluating its characteristics, a biodegradable film was prepared from the gelatin. The results showed that the yield of extracting gelatin, pH and hardness were 12%, 5, and 100 grams, respectively. The gelation time and temperature were 18°C in 175 seconds. Evaluation of the mechanical properties of the edible film based on fish gelatin showed that the tensile strength and elongation at the break point were 3.6 MPa and 27.2%, respectively. The physical properties of thickness, humidity, solubility, and water vapor permeability were reported as 0.08 mm, 5.2%, 21.3%, and 5.8 g mm/h mm²kpa × 10-6, respectively. SEM images showed a smooth structure without pores. Moreover, gelatin film did not show antibacterial properties against E. coli, Staphylococcus aureus, Bacillus subtilis, and Bacillus cereus. However, based on the results of the fish gelatin film can be introduced as a suitable candidate for the preparation of composite films with other biopolymers, and the addition of antibacterial compounds can improve their antibacterial property. [ABSTRACT FROM AUTHOR]

Single-use plastics are a major source of pollution and biodegradable polymers could be the best substitute, as they possess similar barrier and functional properties. Aiming at improving barrier properties and providing antioxidant bioactivity, PLA (PolyLactic Acid) films were coated with a crosslinked suspension of plasticized gelatin incorporating phenolic compounds. The coating process induced weak modifications of PLA properties due to plasticization by moisture and glycerol from the coating suspension. Indeed, a double glass transition was displayed. The water vapor barrier properties of the PLA-coated films were not significantly affected. Phenolic compounds induced a crosslinking of the gelatin network, slightly decreasing the moisture sensitivity and surface hydrophilicity. Therefore, the mechanical properties of PLA were maintained after coating and their barrier properties were highly improved, with up to a 600-fold reduction of the oxygen transfer rate. These results make possible new applications for oxidation-sensitive foods, and even for semi-moist foods. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop novel colorimetric films for food freshness monitoring. UV light irradiation (365 nm) and carbon dots (CDs) were tested as the potential crosslinkers in the fabrication of anthocyanins doped fish gelatin (FG) films. The effect of crosslinkers on the optical, surface, structural, barrier and mechanical properties of FG films was investigated. The incorporation of CDs under UV irradiation improved the tested properties of FG films. The kinetic colorimetric responses of FG films against ammonia vapor were studied to simulate the food spoilage and determine the ammonia sensitivity of the films. Among the tested films, UV-treated FG films containing 100 mg/l (FG-UV-CD100) indicated the best properties. Later, the color difference of FG-UV-CD100 films was observed to correlate well with microbial growth and TVB-N release in skinless chicken breast samples. At the same time, a custom-designed smartphone application (SmartFood) was developed to be used with the FG-UV-CD100 film for quantitative estimation of food freshness in real-time. The proposed food freshness monitoring platform reveals a great potential to minimize global food waste and the outbreak of foodborne illness. [Display omitted] • Both CD addition and UV irradiation exposure improved the physicochemical properties of FG films. • The color change of the FG-UV-CD100 film was correlated well with the alteration of total microbial load and TVB-N levels. • User friendly smartphone application aka SmartFood was developed to be used with the FG-UV-CD100 film. • SmartFood was successfully used for quantitative estimation of the spoilage of skinless chicken breast. [ABSTRACT FROM AUTHOR]

Active packaging using eco-friendly and nontoxic materials is a great choice for protecting the environment while extending the shelf life of food products. The current research investigated the antibacterial, antioxidant, and mechanical characteristics of fish gelatin films incorporated with two different eco-friendly agents (essential oil extracted from Oliveria decumbens Vent, and lysozyme) for active packaging. Fish gelatin film without additives was used as the control film. SEM analysis revealed that adding enzyme or herb extract causes significant changes in the films structure depending on the type and amount of the additives. FTIR analysis indicated some changes in the density of characteristic bands of the gelatinous films when the essential oil and/or lysozyme were added. The solubility, water vapor permeability, and tensile strength of gelatin films containing either essential oil or enzyme significantly (P < 0.05) decreased compared to the control film. Adding essential oil extracted from Oliveria decumbens Vent significantly improved the antibacterial and antioxidant activity of the gelatin film compared to the lysozyme. Gelatin films containing only 3% herb extract showed radical scavenging activity of about 71.18%, while the films containing less than 6% lysozyme did not indicate any significant antioxidant properties. Besides, only films incorporated with the herb extract exhibited antimicrobial activity against both Gram-positive and Gram-negative bacteria. This study revealed that the antioxidant and antibacterial activity of the herb extract are more significant compared to lysozyme. [ABSTRACT FROM AUTHOR]

Fish gelatin hydrogels are typically characterized by weak texture and poor thermal stability. To address this issue, fish gelatin (FG) was modified using κ-carrageenan (κC) and transglutaminase (TG). FG-κC, FG-TG, and FG-κC-TG gels were prepared. The results demonstrated that the particle size and textural properties of FG gels were significantly enhanced by κC and κC-TG composite modifications, and their zeta potential was reduced (P < 0.05). As opposed to that, the improvement effects of TG modification were weaker. The highest particle size and hardness, along with the lowest zeta potential, were exhibited by the FG-κC-TG 0.06% gel. Additionally, the FG-κC-TG gel system possessed higher apparent viscosity and elastic storage modulus. Fluorescence spectroscopy and UV absorption analysis indicated that fluorescence intensity was reduced by all three modification methods, and the conformational structure of FG was altered to varying degrees. Microstructure, FTIR, and XRD results revealed that the number of hydrogen bonds and isopeptide bonds in the composite gel systems was increased by κC and κC-TG modifications, enhancing the stability and orderliness of the gel's helical structure, and forming larger aggregates and denser network structures. Furthermore, due to the presence of covalent cross-linking, improved thermal stability was exhibited by the modified gelatin hydrogels. This study not only provides theoretical support for enhancing the performance of fish gelatin but also facilitates the application of modified fish gelatin in improving the sensory quality and flavor characteristics of food, as well as in serving as a matrix material in the biomedical field. [Display omitted] • The improvement effect of composite modification on FG is the most significant. • The FG-κC-TG gel exhibited superior rheological and textural properties. • Hydrogen and isopeptide bonds are associated with the ordered helical structures in FG. • The thermal stability of FG is improved after modification. [ABSTRACT FROM AUTHOR]

Herein, the complex coacervation of low methoxy pectin (LMP) with three types of gelatins was explored to encapsulate fish oil. The fish oil@gelatin-LMP complex coacervates with good precipitation separation could be obtained at low gelatin concentrations (Fish gelatin, FG: 10–80 mg/mL; porcine skin gelatin, PSG: 10–40 mg/mL; bovine skin gelatin, BSG: 10–80 mg/mL), high gelatin: fish oil mass ratios (4:1–1:1), appropriate gelatin: LMP mass ratios (3:1–12:1 for FG and PSG, 6:1 for BSG), and appropriate pH (FG: 4.90–5.50; PSG: 4.80–5.40; BSG: 4.10–4.50). FG induced similar loading ability, lower encapsulation ability, and comparable peroxide values to the mammalian gelatins. FG induced higher or similar free fatty acid released percentages to mammalian gelatins in the in vitro gastrointestinal model at low gelatin concentrations (10–40 mg/mL). These results provided useful information to understand the protein-polysaccharide complex coacervation to encapsulate oil-based bioactive substances. [Display omitted] • Fish oil@gelatin-low methoxy pectin powders were prepared with complex coacervation • High gelatin concentration inhibited the formation of complex coacervates • High gelatin: pectin mass ratio could promote the formation of complex coacervates • Fish gelatin induced lower encapsulation ability of the powders than mammalian ones • Fish gelatin induced higher or similar free fatty acid release than mammalian ones. [ABSTRACT FROM AUTHOR]

Dysphagia, increasingly prevalent among the aging population, poses significant nutritional challenges. 3D printing technology offers an innovative solution by creating visually appealing and appetizing dysphagia diets, offering new avenues for enhancing the dining experience of individuals with swallowing difficulties. This study explores the feasibility of using 3D printing to produce nutritionally dense meals for individuals with dysphagia. Techniques like SEM and FTIR were employed to examine ingredient interactions. Rheological properties and printing behavior were analyzed, revealing that xanthan gum (XG) as a thickener increases yield stress, elastic modulus (G′), and apparent viscosities of the ink compositions. Modest additions of XG (0.23% and 0.44%) improved the microstructure and mechanical properties, while higher concentrations (XG-0.77%) caused phase separation and reduced mechanical strength. The 3D printed products were evaluated according to IDDSI guidelines and sensory tests. XG-0.44% samples showed precise printing, excellent self-support, smooth textures, and favorable sensory evaluations, qualifying as level 4-pureed/extremely thick dysphagia diets. This study highlights the potential of 3D printing technology in creating nutritious and appealing meals for individuals with dysphagia. [Display omitted] • A personalized nutritious dysphagia-friendly diet was created using 3D printing technology. • The ink used, made from fish gelatin and vegetable puree, demonstrated excellent printing capabilities. • The printed items retained their intended shapes effectively. • The addition of xanthan gum enhanced the rheological properties of the food ink. • The study broadened the variety of materials suitable for 3D printing food. [ABSTRACT FROM AUTHOR]

Recently, the electronic waste (E-waste) has become the most serious environmental trouble because of the iteration of electronic products. Transparent conductive films (TCFs) are the key component of flexible electronic devices, so the development of devices based on degradable TCFs has become an important way to alleviate the problem of E-waste. Gelatin, one of the most prevalent natural biomacromolecules, has drawn increasing attention due to its good film-forming ability, superior biocompatibility, excellent degradability, and commercial availability at a relatively low cost, but has few applications in flexible electronics. Here, we report a method for preparing flexible TCF based on naturally degradable material-fish gelatin, in which silver nanowires and Ti3C2Tx flakes were used as conductive fillers. The obtained TCF has low roughness (RMS roughness = 5.62 nm), good photoelectric properties (Rs = 25.2 Ω/sq., T = ca.85% at 550 nm), strong interfacial adhesion and good degradability. Moreover, the film showed excellent application in the field of EMI shielding and green light OLED device. We believe that these TCFs will shine in the smart wearable field in the future.

Pectin, a kind of natural polysaccharide, shows the attractive potential as a natural stabilizer for protein emulsion. The aim of this study is to investigate the effect of pectin on the physical stability, rheology, interface, and interaction properties of the fish gelatin (FG) emulsion, as pectin was utilized to improve the stability of FG, fish oil emulsion. During the study, when pH < 6, the FG-pectin emulsion displayed better storage stability and salinity tolerance. Analyzing the result, pectin could avoid phase separation at the freeze-thaw process and prevent the liquid-gel transition of FG emulsions during storage. On the other hand, when pH ≥ 6, the emulsion displayed high viscosity due to the complex flocculation and stratified during long-term storage. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding of the FG-pectin complexes in the emulsion were all reduced. Overall, pectin improved the stability of FG emulsions through electrostatic repulsion, hydrophobic interactions, and steric hindrance.

This study aimed to prepare gelatin–fucoidan microspheres with enhanced doxorubicin binding efficiency and controllable biodegradation using fish gelatin combined with low molecular weight (LMW) gelatin and fucoidan at fixed ratios. The MW of gelatin was modified by subcritical water (SW), which is known as a safe solvent, at 120 °C, 140 °C, and 160 °C. In addition, gelatin–fucoidan microspheres were prepared using a solvent exchange technique. Our findings revealed that particle size decreased, the surface was rougher, the swelling ratio increased, and particle shape was irregular in microspheres composed of SW-modified gelatin. Doxorubicin binding efficiency was improved by fucoidan and SW-modified gelatin at 120 °C but not at 140 °C and 160 °C. Interestingly, an increase in in vitro enzymatic degradation was observed in the microspheres consisting of SW-modified fish gelatin, although the cross-linking degree between them was not significantly different. This is because LMW gelatin could form more cross-linked bonds, which might be weaker than the intramolecular bonds of gelatin molecules. Gelatin–fucoidan microspheres consisting of SW-modified fish gelatin with controlled biodegradation rates could be a candidate for a short-term transient embolization agent. In addition, SW would be a promising method to modify the MW of gelatin for medical applications.

The phase behavior of aqueous mixtures of fish gelatin (FG) and sodium alginate (SA) and complex coacervation phenomena depending on pH, ionic strength, and cation type (Na+, Ca2+) were studied by turbidimetric acid titration, UV spectrophotometry, dynamic light scattering, transmission electron microscopy and scanning electron microscopy for different mass ratios of sodium alginate and gelatin (Z = 0.01–1.00). The boundary pH values determining the formation and dissociation of SA-FG complexes were measured, and we found that the formation of soluble SA-FG complexes occurs in the transition from neutral (pHc) to acidic (pHφ1) conditions. Insoluble complexes formed below pHφ1 separate into distinct phases, and the phenomenon of complex coacervation is thus observed. Formation of the highest number of insoluble SA-FG complexes, based on the value of the absorption maximum, is observed at рHopt and results from strong electrostatic interactions. Then, visible aggregation occurs, and dissociation of the complexes is observed when the next boundary, pHφ2, is reached. As Z increases in the range of SA-FG mass ratios from 0.01 to 1.00, the boundary values of рНc, рHφ1, рHopt, and рHφ2 become more acidic, shifting from 7.0 to 4.6, from 6.8 to 4.3, from 6.6 to 2.8, and from 6.0 to 2.7, respectively. An increase in ionic strength leads to suppression of the electrostatic interaction between the FG and SA molecules, and no complex coacervation is observed at NaCl and CaCl2 concentrations of 50 to 200 mM.

This study investigated the effects of ultrasound-assisted phosphorylation on gelling properties of fish gelatin (FG). Ultrasound-assisted phosphorylation (UP) for 60, 90, and 120 min resulted in >6.54% increase of phosphorylation degree and decreased zeta potential of FG. Atomic force microscopy revealed that UP-FGs showed larger aggregates than P-FGs (normal phosphorylation FGs). Low frequent-NMR and microstructure analysis revealed that phosphorylation enhanced water-binding capability of FG and improved the gel networks. However, UP60 had the highest gel strength (340 g), gelling (17.96 °C) and melting (26.54 °C) temperature while UP90 and UP120 showed slightly lower of them. FTIR analysis indicated thatβ-sheet and triple helix content increased but random coil content decreased in phosphorylated FGs. Mass spectrometry demonstrated phosphate groups mainly bound to serine, threonine and tyrosine residues of FG and UP-FG exhibited more phosphorylation sites. The study showed that mild phosphorylation (UP60) could be applied to improve FG gel properties. [Display omitted] • Ultrasound assistance increased the phosphorylation degree and sites of FG. • Phosphate group mainly bound to serine, threonine and tyrosine residues of FG. • Moderate phosphorylation increased water binding ability, GS, GT and MT of FG. • Over phosphorylation led to poor gel network and gel properties of FG. [ABSTRACT FROM AUTHOR]

Biodegradable films have been developed as a potential replacement for plastic in food packaging. Apart from reducing environmental pollution, biodegradable films can be used to prevent quality degradation and extend the storage life of food products. Hybrid kappa carrageenan biopolymers have been developed by introducing SiO2 and ZnO nanoparticles to enhance film characteristics with good packaging quality. However, the composite possessed low transparency and high solubility. Therefore, this study aimed to introduce fish gelatin (FG) into a semi-refined kappa-carrageenan (SRkC) composite to improve the transparency and decrease the solubility properties. The films were prepared at various concentrations of blended polymers of SRkC and FG at different ratios (1:3, 1:1, 3:1) and SiO 2 –ZnO nanoparticles as fillers. The results concluded that as the increase of FG concentrations, the solubility properties of films are likely to decrease. Among the blended films, the films with a ratio of SRkC:FG (1:1) revealed the highest transparency with high UV screening. It also produced films prone to be degraded by the environment. Thus, this knowledge of the bionanocomposite film properties could provide useful contributions to food packaging applications. [Display omitted] • FG and SRkC concentration affected the properties of bionanocomposite film. • FG improve the transparency and solubility of SRkC film. • SRkC: FG (1:1) film showed the highest transparency and high UV screening. • Increasing FG content led to film that was more susceptible to degradation. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the functional and structural properties of phosphorylated fish gelatin (FG) with sodium pyrophosphate (STMP) through wet-heating under various wet-heating times (0.5, 1, 1.5, and 2 h) and pH levels (5, 7, 9, and 11), which was named as PT and PP group, respectively. Results showed that proper phosphorylation time and pH significantly enhanced the gel strength, emulsifying and foaming properties of FG, especially for the PT group. Rheological analysis showed that long phosphorylation time (1–1.5 h) and low pH (5–7) increased the apparent viscosity of FG, slightly increased gelling point and melting point. Environmental scanning electron microscopy revealed a uniform and denser microstructure in phosphorylated FG. Surface hydrophobicity and intrinsic fluorescence indicated that longer phosphorylation times led to increased exposure of hydrophobic and chromophoric groups, but this exposure was limited by phosphorylation pH. The FT-IR spectrum confirmed that the STMP phosphorylated FG by the formation of P O bond. LC-MS/MS analysis showed that the main phosphorylation sites of FG were serine, threonine and tyrosine. Overall, proper phosphorylation time and pH was an effective method for enhancing the gelling properties of FG. This study further deepens our understanding of the interaction between STMP and FG, and promotes the potential application of STMP to novel food products. [Display omitted] • Proper time and pH of phosphorylation improved gelling properties of FG. • Phosphorylated FG has better gelling point and melting point. • The main phosphorylation sites were serine, threonine and tyrosine residues. • The formed C–O–P bond contributed FG to form uniform and dense gel network. [ABSTRACT FROM AUTHOR]

Food packaging based on natural polymers from polysaccharides and proteins can be an alternative to replace conventional plastics. In the present study, semi-refined iota carrageenan (SRIC) and fish gelatin (FG) were used as polymer matrix film with different concentration ratios (0.5:1.5 %, 1.0:1.0 % and 1.5:0.5 % w /w) and SiO 2 -ZnO nanoparticles were incorporated as fillers with the same concentration in all formulas (0.5:1.5 % w/w carrageenan-fish gelatin). This study aimed to develop films for food packaging applications with desirable physical, mechanical, optical, chemical, and microbiological properties. The results showed that incorporating SiO 2 -ZnO nanoparticles significantly (p < 0.05) improved the films' elongation at break, UV-screening properties, and antimicrobial activity. Also, the films' thickness, degradability, and transparency significantly (p < 0.05) increased with the higher concentration of fish gelatin addition in the SRIC matrix polymer. The best formula was obtained on the SRIC-FG film at the ratio of 1.5:0.5 % w /w, which performed excellent antimicrobial activity. Thus, semi-refined iota carrageenan/fish gelatin-based biocomposite film incorporated with SiO 2 -ZnO nanoparticles can be potentially developed as eco-friendly and intelligent food packaging materials to resolve traditional plastic-related issues and prevent food waste. [Display omitted] • Combining SRIC, FG, and SiO 2 -ZnO nanoparticles given promising biocomposite films • Surface morphology and FTIR results represented compatibility between SRIC and FG • Incorporation of nanoparticles significantly improved EAB and antimicrobial activity • Higher proportion of SRIC reinforced film's contact angle and thermal stability • The addition of FG notably enhanced the film's thickness, degradability, and transparency [ABSTRACT FROM AUTHOR]

In this study, the effect of gamma irradiation (10 kGy) on proteins extracted from animal hide, scales, and wool was evidenced by calorimetric (μDSC) and spectroscopic (IR, circular dichroism, and EPR) methods. Keratin was obtained from sheep wool, collagen and bovine gelatin from bovine hide, and fish gelatin from fish scales. The μDSC experiments evidenced that gamma irradiation influences the thermal stability of these proteins differently. The thermal stability of keratin decreases, while a resistance to thermal denaturation was noticed for collagen and gelatins after gamma irradiation. The analysis of the IR spectra demonstrated that gamma irradiation determines changes in the vibrational modes of the amide groups that are associated with protein denaturation, most meaningfully in the case of keratin. As evidenced by circular dichroism for all proteins considered, exposure to gamma radiation produces changes in the secondary structure that are more significant than those produced by UV irradiation. Riboflavin has different effects on the secondary structure of the investigated proteins, a stabilizing effect for keratin and fish gelatin and a destabilizing effect for bovine gelatin, observed in both irradiated and non-irradiated samples. The EPR spectroscopy evidences the presence, in the gamma-irradiated samples, of free radicals centered on oxygen, and the increase in their EPR signals over time due to the presence of riboflavin.

Fish gelatin has been increasingly used as a safe alternative to cattle and pig gelatin due to its similar structure, avoiding the health and socio-cultural issues associated with the use of materials of mammalian origin. Fish gelatin can be produced from processed fish products to achieve a high yield at a low cost. Recent studies show that although fish gelatin comes from a wide range of sources, the protein content and amino acid composition of fish gelatin from different sources are different, and some fish gelatin is soft and unstable transglutaminase (TGase) can catalyze the γ-amide group of glutamine residues and the ε-amino group of lysine residues in proteins to form covalent bonds to form a stable protein network structure, improve the strength of the gel so that it can be applied in a more special environment. In this experiment, after screening the raw materials of cold-water fish gelatin M06 and M08, warm-water fish gelatin M03 and M04, a strong fish gelatin was successfully prepared by catalytic modification of cold-water fish gelatin by transglutaminase (TGase), and the excellent performance of TG enzyme-catalyzed modified gelatin was proved through the application effect of chicken salt soluble protein. In this experiment, the protein content of cold-water fish M08 was the highest, which was up to 99.9%, 1.09 times that of warm-water fish. The gelatin content of cold-water fish M08 was the highest of the four kinds of fish gelatin, with a wide proportion of components and rich amino acid composition. Cold-water fish M08 gelatin-derived gel had the highest strength of 253 ± 1 g/cm at 4 °C. It was found that fish gelatin with protein molecular weight distribution and rich amino acid composition had higher gel strength. M08 gelatin is cross-linked by transglutaminase (TGase), which increases the strength of enzyme gels by approximately 200% compared to self-assembled gels. Fish gelatin catalyzed by the TG enzyme improves the gel strength of raw material and makes it more applicable. M08 gelatin also showed good application performance at low temperatures in compound chicken salt-soluble protein gel, with a water retention rate of 95.84% and gel strength of 198.5 g/cm. This study expanded the application range of fish gelatin by TG enzyme and improved the application potential of fish gelatin.

PLA (polylactic acid) is one of the three major biopolymers available on the market for food packaging, which is both bio-based and biodegradable. However, its performance as a barrier to gases remains too weak to be used for most types of food, particularly oxygen-sensitive foods. A surface treatment, such as coating, is a potential route for improving the barrier properties and/or providing bioactive properties such as antioxidants. Gelatin-based coating is a biodegradable and food-contact-friendly solution for improving PLA properties. The initial adhesion of gelatin to the film is successful, both over time and during production, however, the coating often delaminates. Corona processing (cold air plasma) is a new tool that requires low energy and no solvents or chemicals. It has been recently applied to the food industry to modify surface properties and has the potential to significantly improve gelatin crosslinking. The effect of this process on the functional properties of the coating, and the integrity of the incorporated active compounds were investigated. Two coatings have been studied, a control fish gelatin-glycerol, and an active one containing gallic acid (GA) as a natural antioxidant. Three powers of the corona process were applied on wet coatings. In the test conditions, there were no improvements in the gelatin crosslinking, but the corona did not cause any structural changes. However, when the corona and gallic acid were combined, the oxygen permeability was significantly reduced, while free radical scavenging, reduction, and chelating properties remained unaffected or slightly improved.

Marine-origin gelatin has been increasingly used as a safe alternative to bovine and porcine ones due to their structural similarity, avoiding the health-related problems and sociocultural concerns associated with using mammalian-origin materials. Another benefit of marine-origin gelatin is that it can be produced from fish processing-products enabling high production at low cost. Recent studies have demonstrated the excellent capacity of gelatin-methacryloyl (GelMA)-based hydrogels in a wide range of biomedical applications due to their suitable biological properties and tunable physical characteristics, such as tissue engineering applications, including the engineering of cartilage. In this study, fish gelatin was obtained from Greenland halibut skins by an acidic extraction method and further functionalized by methacrylation using methacrylic anhydride, developing a photosensitive gelatin-methacryloyl (GelMA) with a degree of functionalization of 58%. The produced marine GelMA allowed the fabrication of photo-crosslinked hydrogels by incorporating a photoinitiator and UV light exposure. To improve the biological performance, GelMA was combined with two glycosaminoglycans (GAGs): hyaluronic acid (HA) and chondroitin sulfate (CS). GAGs methacrylation reaction was necessary, rendering methacrylated HA (HAMA) and methacrylated CS (CSMA). Three different concentrations of GelMA were combined with CSMA and HAMA at different ratios to produce biomechanically stable hydrogels with tunable physicochemical features. The 20% (w/v) GelMA-based hydrogels produced in this work were tested as a matrix for chondrocyte culture for cartilage tissue engineering with formulations containing both HAMA and CSMA showing improved cell viability. The obtained results suggest these hybrid hydrogels be used as promising biomaterials for cartilage tissue engineering applications.