Commercial cold-water fish skin gelatin and bovine bone gelatin: Structural, functional, and emulsion stability differences

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.

Fabrication, modification, interaction mechanisms, and applications of fish gelatin: A comprehensive review

Fish gelatin (FG) is an essential natural biopolymer isolated from aquatic sources and has been considered as a feasible substitute for mammalian gelatins. However, its inferior mechanical and gelling properties limit its applications. Consequently, FG has been modified using various methods. This review summarizes the extraction techniques (including traditional acid and alkaline methods, as well as newer technologies such as ultrasonic-assisted and microwave-assisted extraction), modification strategies (mechanical treatments, physical mixing with polysaccharides, utilization of the Hofmeister effect, chemical modifications, etc.), along with their mechanisms of action. Additionally, we discussed the applications of FG and its modified products. Furthermore, this review highlights the safety and prospects for FG and its derivatives. The mechanical properties and biological functions of FGs are enhanced after modification. Thus, modified FG composites exhibit diverse applications in areas such as foaming agents and emulsifiers, food packaging, three-dimensional printing, drug delivery systems and tissue engineering. This paper aims to provide comprehensive information for future research on FG with the intention of broadening its applicability within the industries of food, cosmetics, and pharmaceuticals. Nevertheless, the development of tough gels, aerogels, and stimuli-responsive hydrogels based on FG requires further investigation.

Water as a Structural Marker in Gelatin Hydrogels with Different Cross-Linking Nature

We have studied the molecular properties of water in physically and chemically cross-linked gelatin hydrogels by FTIR-spectroscopy, NMR relaxation, and diffusivity and broadband dielectric spectroscopy, which are sensitive to dynamical properties of water, being a structural marker of polymer network. All experiments demonstrated definite reinforcement of the hydrogel net structure and an increase in the amount of hydrate water. FTIR experiments have shown that the chemical cross-linking of gelatin molecules initiates an increase in the collagen-like triple helices "strength", as a result of infused restriction on protein molecular mobility. The "strengthening" of protein chains hinders the mobility of protein fragments, introducing complex modifications into the structural properties of water which are remained practically unchanged up to up to 30-40 °C.

Effects of five tissue sources of silver carp by-products on the structure, physicochemical and emulsifying properties of gelatin

The effects of tissue sources on gelatin's physicochemical and functional properties remain unclear. This work aimed to analyze the effects of five tissue sources on the properties of fish gelatins. Five gelatins were extracted from different silver carp by-products (skin, scale, fin, head, and bone) and the effects of tissue sources on the gelatin's properties were studied. The gelatin's β-sheet percentages and total sodium dodecyl sulfate-polyacrylamide gel electrophoresis band intensities (β, α1, and α2 chains) showed similar dependence to the tissue sources: skin ≈ scale > fin ≈ head > bone. Bone-related gelatins (from head and bone) showed lower water-holding capacity and fat-binding capacity values than the other gelatins. Tissue sources significantly affected the gelatin's gel strength values: skin ≈ fin > scale > bone ≈ head. Scale and bone gelatin solutions had significantly lower rheological apparent viscosities than other by-product gelatin solutions. The interfacial tension and rheological apparent viscosity values of the fish oil-loaded gelatin-stabilized emulsions depended on the gelatin tissue sources and gelatin concentrations. In particular, skin, scale, and fin gelatins induced no obvious emulsion creaming at the gelatin concentration of 10 g/L during the emulsion storage. Bone-related gelatins induced higher emulsion creaming index values for the emulsions with 10 g/L of gelatins during the emulsion storage. This work confirmed tissue sources could significantly affect the properties of gelatins. Five tissue sources had different effects on the structural, physicochemical, and emulsifying properties of silver carp by-product gelatins. Especially, the gelatins from different silver carp by-products showed different water-holding and fat-binding capacities, gel strengths, interfacial tension, rheological apparent viscosities, and emulsion stabilization abilities. These properties are important considerations for the application of silver carp by-product gelatins in food and other industries.

Effects of the extraction temperatures on the protein contents, gelatin purities, physicochemical properties, and functional properties of tilapia scale gelatins

Herein, the effects of the extraction temperatures (45, 55, 65, 75, and 85 °C) on the protein contents, gelatin purities, physicochemical properties, and functional properties of tilapia scale gelatins were studied. Among these temperatures, 65 °C was the best extraction temperature to obtain good production yield (16.0 % ± 0.3 %), good protein contents (excellent total amino acid composition of 94.20 ± 0.76 g/100 g of gelatin, the highest hydrophobic amino acids percentage of 32.68 ± 0.24 g/100 g of gelatin), appropriate ATR-FTIR spectra peaks (Amides A, B, I, II, and III), high β-sheet percentage (38.2 % ± 1.3 %), the highest purity of the gelatin structures (280, 140, and 125 kDa), the lowest nanoparticle sizes in atomic force microscopy results, the highest water-holding capacity (25.3 % ± 0.9 %), the highest fat-binding capacity (16.9 % ± 0.1 %), high foaming properties (foaming capacity of 151.7 % ± 7.6 % and foaming stability of 145.8 % ± 6.3 %), the lowest interfacial tension (2.1 ± 0.2 mN/m), the lowest emulsifying activity index (16.5 % ± 0.9 %), the highest emulsifying stability index (88.9 % ± 5.1 %), highest emulsion viscosity (1462 ± 17 mPa·s at the rotary speed of 6 rpm), the lowest initial droplet sizes, and lowest emulsion creaming index (6.9 % ± 0.7 %). This work provided a useful guide to choosing extraction temperature for gelatin extraction and a useful theory on the relationship between compositions and properties of a protein sample.

A Review on Fish Skin-Derived Gelatin: Elucidating the Gelatin Peptides-Preparation, Bioactivity, Mechanistic Insights, and Strategies for Stability Improvement

Fish skin-derived gelatin has garnered significant attention recently due to its abundant availability and promising bioactive properties. This comprehensive review elucidates various intricacies concerning fish skin-derived gelatin peptides, including their preparation techniques, bioactive profiles, underlying mechanisms, and methods for stability enhancement. The review investigates diverse extraction methods and processing approaches for acquiring gelatin peptides from fish skin, emphasizing their impact on the peptide composition and functional characteristics. Furthermore, the review examines the manifold bioactivities demonstrated by fish skin-derived gelatin peptides, encompassing antioxidant, antimicrobial, anti-inflammatory, and anticancer properties, elucidating their potential roles in functional food products, pharmaceuticals, and nutraceuticals. Further, mechanistic insights into the functioning of gelatin peptides are explored, shedding light on their interactions with biological targets and pathways. Additionally, strategies aimed at improving the stability of gelatin peptides, such as encapsulation, modification, and integration into delivery systems, are discussed to extend the shelf life and preserve the bioactivity. Overall, this comprehensive review offers valuable insights into using fish skin-derived gelatin peptides as functional ingredients, providing perspectives for future research endeavors and industrial applications within food science, health, and biotechnology.

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.

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.

Molecular modification of low-dissolution soy protein isolates by anionic xanthan gum, neutral guar gum, or neutral konjac glucomannan to improve the protein dissolution and stabilize fish oil emulsion

Herein, the effects of anionic xanthan gum (XG), neutral guar gum (GG), and neutral konjac glucomannan (KGM) on the dissolution, physicochemical properties, and emulsion stabilization ability of soy protein isolate (SPI)-polysaccharide conjugates were studied. The SPI-polysaccharide conjugates had better water dissolution than the insoluble SPI. Compared with SPI, SPI-polysaccharide conjugates had lower β-sheet (39.6 %-56.4 % vs. 47.3 %) and α-helix (13.0 %-13.2 % vs. 22.6 %) percentages, and higher β-turn (23.8 %-26.5 % vs. 11.0 %) percentages. The creaming stability of SPI-polysaccharide conjugate-stabilized fish oil-loaded emulsions mainly depended on polysaccharide type: SPI-XG (Creaming index: 0) > SPI-GG (Creaming index: 8.1 %-21.2 %) > SPI-KGM (18.1 %-40.4 %). In addition, it also depended on the SPI preparation concentrations, glycation times, and glycation pH. The modification by anionic XG induced no obvious emulsion creaming even after 14-day storage, which suggested that anionic polysaccharide might be the best polysaccharide to modify SPI for emulsion stabilization. This work provided useful information to modify insoluble proteins by polysaccharides for potential application.

Effects of Maillard reaction of different monosaccharide-modified on some functional properties of fish gelatin

In this work, the effects of Maillard reaction of different monosaccharide-modified fish gelatin were studied. The changes of gel properties, rheology and structure of fish gelatin before and after modification were compared and analyzed, and oil-in-woter emulsions were prepared. The results showed that the five-carbon monosaccharide had stronger modification ability than the six-carbon monosaccharide, which was mainly due to the different steric hindrance of the amino acids in the nuclear layer and the outer layer to the glycosylation reaction. With the progress of the Maillard reaction, the color of fish gelatin gradually became darker. The attachment of sugar chains inhibited the gelation process of fish gelatin, decreased the gelation rate, changed the secondary structure, increased the content of β-turn or α-helix, increased the degree of fluorescence quenching, and enhanced the emulsifying properties and emulsion stability. This study provides useful information for the preparation of different types of monosaccharide-modified proteins and emulsions.

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.

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.

Effect of seasonal variation and farming systems on the properties of Nile tilapia gelatin extracted from scales

Although fish gelatin has become a research hotspot in recent years, researchers and manufacturers are still looking for high-quality sources of fish galatin to meet the commercial demand for safer gelatin.became This study aimed to evaluate the impact of seasonal variation and farming systems on the properties of gelatin extracted from Nile tilapia scales. Gelatin extracted from farmed tilapia had lowest impurities, higher clarity as well as desirable color characteristics (L* = 65.95 and a* = -0.33). The protein and fat composition of Wild (91.00 ± 0.00c) and 1.94 ± 0.05a respectively were higher than farmed gelatin of protein (91.00 ± 0.00c) and fat (0.84 ± 0.08b) but gelatin from the farmed type were clearer (98.30 ± 0.28a) than wild type (94.60 ± 0.28b). In addition, the XRD analysis confirmed its amorphous structure (2θ = 11°, 21°. 29°, and 31°). The gelatin extracted from wild tilapia showed an average yield of 1.98 % and good physicochemical and functional properties. Furthermore, FTIR indicated a strong bond positioned in the amide I region (1650.88 cm-1) of the wild tilapia gelatin. Partial Least Square (PLS) confirmed that viscosity is positively correlated with melting temperature upon a unit change in gelatin yield. This work highlights the significance of farming systems and seasonal variation in extraction conditions and great parameter to comprehensively navigate the functional, biochemical, and physical properties of Nile tilapia gelatin for broadening both food and non-food industrial appliactions.

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.

Underused Marine Resources: Sudden Properties of Cod Skin Gelatin Gel

The main object of this work was to characterize the structure and properties of laboratory-made fish gelatin from cod skin in comparison with known commercial gelatins of fish and mammalian origin. This is one way we can contribute to the World Food Program and characterize foodstuff resources from alternative natural sources. Our research was based on the combination of an expanded set of complementary physical-chemical methods to study the similarities and distinctions of hydrogels from traditional and novel gelatin sources from underused marine resources. In this work, we have compared the morphology, supramolecular structure and colloid properties of two commercial (mammalian and fish) gelatins with gelatin we extracted from cold-water cod skin in laboratory conditions. The obtained results are novel, showing that our laboratory-produced fish gelatin is much closer to the mammalian one in terms of such parameters as thermal stability and strength of structural network under temperature alterations. Especially interesting are our experimental observations comparing both fish gelatins: it was shown that the laboratory-extracted cod gelatin is essentially more thermally stable compared to its commercial analogue, being even closer in its rheological properties to the mammalian one.

Ultrasonic-Assisted Glycosylation with Glucose on the Functional and Structural Properties of Fish Gelatin

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.

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.

Impacts of hesperidin on whey protein functionality: Interacting mechanism, antioxidant capacity, and emulsion stabilizing effects

The objective of this work was to explore the possibility of improving the antioxidant capacity and application of whey protein (WP) through non-covalent interactions with hesperidin (HES), a citrus polyphenol with nutraceutical activity. The interaction mechanism was elucidated using several spectroscopic methods and molecular docking analysis. The antioxidant capacity of the WP-HES complexes was analyzed and compared to that of the proteins alone. Moreover, the resistance of oil-in-water emulsions formulated using the WP-HES complexes as antioxidant emulsifiers to changes in environmental conditions (pH, ion strength, and oxidant) was evaluated. Our results showed that HES was incorporated into a single hydrophobic cavity in the WP molecule, where it was mainly held by hydrophobic attractive forces. As a result, the microenvironments of the non-polar tyrosine and tryptophan residues in the protein molecules were altered after complexation. Moreover, the α-helix and β-sheet regions in the protein decreased after complexation, while the β-turn and random regions increased. The antioxidant capacity of the WP-HES complexes was greater than that of the proteins alone. Non-radiative energy transfer from WP to HES was detected during complex formation. Compared to WP alone, the WP-HES complexes produced emulsions with smaller mean droplet diameters, exhibited higher pH and salt stability, and had better oxidative stability. The magnitude of these effects increased as the HES concentration was increased. This research would supply valuable information on the nature of the interactions between WP and HES. Moreover, it may lead to the creation of dual-function antioxidant emulsifiers for application in emulsified food products.

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.

Potential of a Composite Conduit with Bacterial Nanocellulose and Fish Gelatin for Application as Small-Diameter Artificial Blood Vessel

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.

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.

Intermolecular Interactions in the Formation of Polysaccharide-Gelatin Complexes: A Spectroscopic Study

Gelatin, due to its gelling and stabilizing properties, is one of the widely used biopolymers in biotechnology, medicine, pharmaceuticals, and the food industry. One way to modify the characteristics of gelatin is molecular modification by forming non-covalent polyelectrolyte complexes with polysaccharides based on the self-organization of supramolecular structures. This review summarizes recent advances in the study of various types and the role of intermolecular interactions in the formation of polysaccharide-gelatin complexes, and conformational changes in gelatin, with the main focus on data obtained by spectroscopic methods: UV, FT-IR, and 1H NMR spectroscopy. In the discussion, the main focus is on the complexing polysaccharides of marine origin-sodium alginate, κ-carrageenan, and chitosan. The prospects for creating polysaccharide-gelatin complexes with desired physicochemical properties are outlined.

Effects of antioxidant types on the stabilization and in vitro digestion behaviors of silver carp scale gelatin-stabilized fish oil-loaded emulsions

Lipid oxidation is a major challenge in the development and storage of lipid-containing food products. In this work, we extracted aquatic gelatin from silver carp scales and studied the effects of antioxidant types (water-soluble and lipid-soluble types) on the stabilization, lipid oxidation, and in vitro digestion behaviors of silver carp scale gelatin-stabilized fish oil-loaded emulsions. Vitamin C (VC), a water-soluble antioxidant, and vitamin E (VE), a lipid-soluble antioxidant, had no obvious effects on the appearance, droplet size distribution, and droplet stability of the emulsion. VC slowed the liquid-gel transition of the emulsions at room temperature. The emulsion creaming stability decreased with the increase of VC concentration, whereas it increased with the increase of VE concentration. Lipid oxidation hierarchy of emulsion groups at room temperature were VC<VE<control<pure oil. Free fatty acids were mainly released from the silver carp scale gelatin-stabilized emulsions in the simulated intestinal fluid. Moreover, compared with the control group, VC increased the free fatty acid release percentages, whereas VE decreased them. This work provided useful information for developing antioxidants in the field of food science and in value-added utilization research of aquatic by-products.

Effect of carbon numbers and structures of monosaccharides on the glycosylation and emulsion stabilization ability of gelatin

Herein, the effect of saccharide glycosylation by nine monosaccharides on bovine bone gelatin for the stabilization of fish oil-loaded emulsions was explored. The gelatin modification was analyzed and then the emulsifying properties of monosaccharide-modified gelatins were analyzed at pH 9.0 and 3.0. The results demonstrated that glycosylated gelatin structure, droplet stability, creaming stability, and liquid-gel transition time were dependent on monosaccharide carbon numbers, monosaccharide structures, and solution pH. Glycosylation modification of gelatins did not obviously change the emulsion droplet stability at pH 9.0, whereas it increased the emulsion droplet stability at pH 3.0. Glycosylation modification of gelatins did not obviously change the emulsion creaming index values (5.1%-8.4% at pH 9.0 and 25.8%-33.1% at pH 3.0). Three-carbon and four-carbon monosaccharides glycosylation significantly increased emulsion liquid-gel transition times. This work provided useful information to understand the effects of carbon numbers and structures of monosaccharides on the protein modification.

Making Polyol Gummies by 3D Printing: Effect of Polyols on 3D Printing Characteristics

With growth of confectionery industry, there is a great demand for candy shape, and 3D printing technology is way to achieve it. The printing properties of gummy, which is formed of gelatin and low acyl gellan as gel, maltol, erythritol, sorbitol, and xylitol as sweeteners, were tested in this study. Gummies’ rheological properties, 3D printing properties, and textural qualities were measured using a rheometer, FTIR, and SEM in this study. The strength of the hydrogen bonds will be affected by the addition of polyol, after which the excluded volume effect of polyol and viscosity will become the most important aspect. Polyols increased the gelation temperature (Tgelation), improved the gel network, and improved hydrogen bonding in the gel, according to the findings. Yield stress, shear recovery performance, and gel strength were initially increased, then decreased, when polyol concentration was increased. It had a 40.59 °C gelation temperature, an 82.99% recovery rate, noticeable shear thinning features, high self-supporting performance, and textural qualities when ink with 35 g maltitol and 30 g erythritol gave the best printing performance. This research serves as a foundation for the development of individualized, bespoke 3D printed gummies in the future.

Effect of Phosphorylation on the Structure and Emulsification Properties of Different Fish Scale Gelatins

This study aimed to investigate the effect of phosphorylation on the structure and emulsification of Coregonus peled, Esox lucius and Grass carp scale gelatin. Fourier transform infrared spectroscopy (FTIR) and endogenous fluorescence spectra showed that the structures of the three fish scale gelatins changed. Additionally, the surface hydrophobicity index of the three fish scale gelatins increased by 36.72, 31.42 and 111.67, respectively, after 1 h of phosphorylation, and the surface tension decreased by 17.27, 32.58 and 18.7 mN/m, respectively. The emulsification activity index increased by 115.86, 155.22 and 45.52 m²/g, and the emulsification stability index increased by 98.37, 256.77 and 169.61 min, respectively. The structure of fish scale gelatin changed after phosphorylation, which resulted in the improvement of emulsification. This work will provide useful information to understand the relationship between the structure and function of gelatin.

Structural and emulsion stabilization comparison of four gelatins from two freshwater and two marine fish skins

This study analyzed the structural and emulsion stabilization properties of two freshwater and two marine fish skin gelatins: Chinese longsnout catfish skin gelatin (CLCSG), silver carp skin gelatin (SCSG), salmon skin gelatin (SSG), and Alaska pollack skin gelatin (APSG). Their gel strengths (Bloom values) were: 361 ± 1 (SCSG) > 253 ± 4 (CLCSG) > 69 ± 1 (SSG) > 36 ± 2 (APSG). Higher molecular weights and α/β subunit contents of gelatins might induce higher gel strengths. Both creaming and droplet stability were completely the same to the contents of imino acids, β-sheet percentages, and β-turn percentages, whereas they were completely the opposite to random coil percentages. The emulsion stabilization mechanisms involved an "fish skin source - protein chemical composition - protein secondary structure - protein functional properties - emulsion stability" route. This study provided useful knowledges for gelatin science and for the comprehensive utilization of aquatic by-products in gelatin industry.

Repurposing fish waste into gelatin as a potential alternative for mammalian sources: A review

Mammalian gelatin is extensively utilized in the food industry because of its physicochemical properties. However, its usage is restricted and essentially prohibited for religious people. Fish gelatin is a promising alternative with no religious and social restrictions. The desirable properties of fish gelatin can be significantly improved by various methods, such as the addition of active compounds, enzymes, and natural crosslinking agents (e.g., plant phenolics and genipin), and nonthermal physical treatments (e.g., ionizing radiation and high pressure). The aim of this study was to explore whether the properties of fish gelatin (gel strength, melting or gelling temperature, odor, viscosity, sensory properties, film-forming ability, etc.) could be improved to make it comparable to mammalian gelatin. The structure and properties of gelatins obtained from mammalian and fish sources are summarized. Moreover, the modification methods used to ameliorate the properties of fish gelatin, including rheological (gelling temperature from 13-19°C to 23-25°C), physicochemical (gel strengths from ∼200 to 250 g), and thermal properties (melting points from ∼25 to 30°C), are comprehensively discussed. The relevant literature reviewed and the technological advancements in the industry can propel the development of fish gelatin as a potential alternative to mammalian gelatin, thereby expanding its competitive market share with increasing utility.

Anhydride structures affect the acylation modification and emulsion stabilization ability of mammalian and fish gelatins

In this work, ring-like anhydrides (C4, C5, and C6) with different sizes and succinic anhydrides (C4, C10, C12, C14, and C16) with different side chain lengths were used to modify bovine bone gelatin (BBG) and cold-water fish skin gelatin (CFG), and the effect of acylated gelatins on fish oil-loaded emulsions stability was explored. The results showed that the degree of N-acylation decreased with increased ring sizes or side chain lengths, and the surface hydrophobicity of acylated gelatins increased with increased anhydride carbon numbers. Acylated CFGs had higher droplet stability and lower liquid-gel transition time than acylated BBGs. Only BBG-C12 had a slight increase on the creaming stability among these acylated gelatins. These results demonstrated that the gelatins could be modified by all the anhydrides and their emulsion stabilization ability was dependent on the gelatin type and anhydride structure. The results could be beneficial for protein-based emulsifier development and application.

Vacuum freeze-drying of tilapia skin affects the properties of skin and extracted gelatins

Herein, the effects of vacuum freeze-drying treatment of tilapia skin on the properties of skin, the molecular properties of extracted gelatins, and the emulsion stabilization properties of extracted gelatins were studied. The results suggested that all the bound, entrapped, and free water molecules were simultaneously sublimated (quickly at the first 30 min and then slowly) by sublimation in the vacuum freeze-drying process. Long vacuum freeze-drying times (60 and 150 min) decreased the amount of the four bands in SDS-PAGE pattern, increased β-sheet and random coil percentages, and decreased other three secondary structure percentages of extracted gelatins. Finally, vacuum freeze-drying of tilapia skin increased the emulsion stability of fish oil-loaded oil-in-water emulsions. This work provided basic knowledges to illustrate the effect of vacuum freeze-drying of protein-enriched tissues on the molecular and functional properties of extracted proteins. It also provided a potential route to increase the emulsion stabilization ability of proteins.

Recent Advances in Gelatin-Based Nanomedicine for Targeted Delivery of Anti-Cancer Drugs

Nanoparticles based on natural polymers are utilized for the development of a wide range of drug delivery systems (DDS) in the current era. Gelatin-based nanoparticles, for example, are a remarkable cancer therapy with high efficacy and specificity. This paper reviews the recent advancements in gelatin-based nanomedicine for use in cancer therapeutics. Due to the characteristics features of gelatin, such as biocompatibility, biodegradability, stability, and good surface properties, these nanoparticles provide high therapeutic potency in cancer nanomedicine. The surface of gelatin can be modified in a number of ways using various ligands to explore the platform for the development of a more novel DDS. Various methods are available for the preparation of gelatin nanomedicine discussed in this review. In addition, various cross-linkers to stabilized nanocarriers and stimuli base gelatin nanoparticles are reviewed. Furthermore, recent advances and research in gelatin-based nanomedicine are discussed. Also, some drawbacks and challenges are evaluated. In general, this paper paves the pathway to identify the details about the gelatin-based DDS for cancer therapy.

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Marine-Derived Collagen as Biomaterials for Human Health

Collagen is a kind of biocompatible protein material, which is widely used in medical tissue engineering, drug delivery, cosmetics, food and other fields. Because of its wide source, low extraction cost and good physical and chemical properties, it has attracted the attention of many researchers in recent years. However, the application of collagen derived from terrestrial organisms is limited due to the existence of diseases, religious beliefs and other problems. Therefore, exploring a wider range of sources of collagen has become one of the main topics for researchers. Marine-derived collagen (MDC) stands out because it comes from a variety of sources and avoids issues such as religion. On the one hand, this paper summarized the sources, extraction methods and characteristics of MDC, and on the other hand, it summarized the application of MDC in the above fields. And on the basis of the review, we found that MDC can not only be extracted from marine organisms, but also from the wastes of some marine organisms, such as fish scales. This makes further use of seafood resources and increases the application prospect of MDC.

Comparison of silver carp fin gelatins extracted by three types of methods: Molecular characteristics, structure, function, and pickering emulsion stabilization

High value-added utilization of different aquatic by-products is an increasingly urgent issue in aquatic science and industry. In this work, the effects of extraction methods on the molecular characteristics, structural properties, functional properties, and Pickering emulsion stabilization behaviors of silver carp fin gelatins were comprehensively studied. All the results showed molecular characteristics of silver carp fin gelatin was the key parameter to determine their functional properties such as wide gel strength range, excellent water-holding capacity, and excellent Pickering emulsion stabilization ability. The Pickering emulsion stabilization mechanisms of fin gelatins involved an "extraction method - protein molecular characteristics - fat-binding capacity - droplet structure - water phase properties - Pickering emulsion stability" route. This work could be helpful to understand the basic information on how the molecular characteristics determine the functions of gelatins. It would be also useful for the high value-added utilization of aquatic by-products and gelatins.

Silver carp scale gelatins for the stabilization of fish oil-loaded emulsions

Herein, three types of silver carp scale gelatins were extracted, and their molecular weight distribution, structural properties, functional properties and emulsifying properties were investigated and discussed. Acetic acid-extracted gelatin (AAG), hot water-extracted gelatin (HWG), and pepsin enzyme-extracted gelatin (PEG) showed similar and four clear bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern, whereas they showed different β chain amounts and β-sheet percentages. The water-holding capacity values (g/g of gelatin) were: AAG (16.8 ± 1.1) > HWG (14.0 ± 0.7) ≈ PEG (13.5 ± 1.6). The fat-binding capacity values (g/g of gelatin) were: AAG (11.8 ± 0.3) > HWG (9.5 ± 1.3) > PEG (5.3 ± 0.4). Emulsion droplet sizes and creaming index values decreased with the increase of gelatin concentrations for all the fish oil-loaded emulsions stabilized by three types of gelatins. Compared with PEG, AAG and HWG show similar and higher emulsion stability at high gelatin concentration (10 mg/mL). The stabilization mechanism of fish oil-loaded silver carp scale gelatin-stabilized emulsions involved an "extraction method-protein molecular weight distribution-protein molecular structure-molecular interaction-emulsibility-droplet structure-emulsion stability" route. This work would be beneficial for the research on the relationship of structure and function of gelatin and to the comprehensive utilization of aquatic products.

Cosmetic, Biomedical and Pharmaceutical Applications of Fish Gelatin/Hydrolysates

There are several reviews that separately cover different aspects of fish gelatin including its preparation, characteristics, modifications, and applications. Its packaging application in food industry is extensively covered but other applications are not covered or covered alongside with those of collagen. This review is comprehensive, specific to fish gelatin/hydrolysate and cites recent research. It covers cosmetic applications, intrinsic activities, and biomedical applications in wound dressing and wound healing, gene therapy, tissue engineering, implants, and bone substitutes. It also covers its pharmaceutical applications including manufacturing of capsules, coating of microparticles/oils, coating of tablets, stabilization of emulsions and drug delivery (microspheres, nanospheres, scaffolds, microneedles, and hydrogels). The main outcomes are that fish gelatin is immunologically safe, protects from the possibility of transmission of bovine spongiform encephalopathy and foot and mouth diseases, has an economic and environmental benefits, and may be suitable for those that practice religious-based food restrictions, i.e., people of Muslim, Jewish and Hindu faiths. It has unique rheological properties, making it more suitable for certain applications than mammalian gelatins. It can be easily modified to enhance its mechanical properties. However, extensive research is still needed to characterize gelatin hydrolysates, elucidate the Structure Activity Relationship (SAR), and formulate them into dosage forms. Additionally, expansion into cosmetic applications and drug delivery is needed.