Microbial transglutaminase (MTGase) modified fish gelatin-γ-polyglutamic acid (γ-PGA): Rheological behavior, gelling properties, and structure

Enhanced stability of curcumin encapsulated in fish gelatin emulsions combined with γ-Polyglutamic acid

This study examined the rheological properties, interfacial characteristics, particle size, zeta potential, Turbiscan stability index (TSI), morphology, and encapsulation efficiency of curcumin (Cur) loaded fish gelatin (FG) emulsions modified with γ-polyglutamic acid (γ-PGA). The results showed that adding γ-PGA significantly increased curcumin encapsulation efficiency. At 0.3 mg/mL, FG emulsions had an encapsulation efficiency of 80.14 %, while FG-γ-PGA emulsions reached 90.35 %. The FG-γ-PGA emulsions also showed enhanced stability and resistance to phase separation, remaining stable for seven days, compared to three days for FG emulsions. After 24 h, the TSI of FG emulsions with 0.6 mg/mL Cur was 2.46, significantly higher than the 0.55 TSI for FG-γ-PGA emulsions at the same concentration. FG-γ-PGA emulsions had smaller droplet sizes, and analysis of interfacial characteristics, particle size, and zeta potential indicated better system stability than FG emulsions. These improved properties of FG-γ-PGA emulsions highlight their potential as efficient carriers for curcumin. Overall, the favorable characteristics of FG-γ-PGA emulsions suggest promising applications in the food industry, especially for developing functional foods with extended shelf life and enhanced nutritional benefits.

A natural gelatin/casein hydrogel with on-demand adhesion via chitosan solution for wound healing

Adhesive hydrogels have been widely studied as wound dressings due to their excellent biocompatibility and biological activity. However, most designed hydrogels still exist limitations including potentially toxic monomer, complex preparation process and non-degradable property. Here, a natural and degradable gelatin/casein hydrogel was prepared by enzymatic cross-linking. The hydrogel could adhere to tissue on-demand with the mediation of chitosan (CS) solution. It was found that the adhesion strength of hydrogel could be controlled by adjusting gelatin/casein ratio, EDC&NHS concentration, CS concentration, glycerol content and crosslinking degree. To further expand the applicability of hydrogels, the degradation and drug release rate of hydrogels could be modulated by changing transglutaminase (TG) concentration. Moreover, tetracycline hydrochloride (TH) was loaded into hydrogel as a drug model, which endowed hydrogel with good antibacterial properties. It was shown that the 0.03 % TH hydrogel had excellent blood compatibility and cell compatibility, and can promote the healing of infected wounds in mice. This research provides a new natural adhesive hydrogel for biomedical engineering field.

Thermal stability of γ-PGA modified fish gelatin emulsion

BACKGROUND

Emulsions are thermally unstable systems. This research aimed to investigate the thermal stability of fish gelatin (FG) oil-in-water emulsions in the presence of poly-γ-glutamic acid (γ-PGA) as an additive after heat treatment. The study assessed how γ-PGA influences the thermal stability of FG emulsions over time, focusing on their properties, structure, and food application potential.

RESULTS

The incorporation of γ-PGA significantly enhanced the thermal stability of FG emulsions, preserving their morphology after heating. Emulsions containing 0.1% γ-PGA showed no significant changes after 24 h at 90 °C, while emulsions without γ-PGA experienced noticeable delamination. Rheological evaluations revealed that the energy storage modulus and loss modulus of FG-γ-PGA emulsions remained consistently higher than those of FG emulsions, regardless of heating duration. Particle size analysis indicated minimal changes for FG-γ-PGA emulsions (413 nm after 24 h) compared to a substantial increase for FG emulsions (1598 nm). After heating, FG-γ-PGA emulsions demonstrated significantly higher emulsifying activity index (EAI) (74 m2 g-1 versus 22.7 m2 g-1) and emulsifying stability index (ESI) (97% versus 76%). Additionally, the texture properties of meat mince formulated with FG-γ-PGA emulsions were comparable to those containing fat, showcasing their potential as a fat replacement.

CONCLUSION

The study concludes that γ-PGA enhances the thermal stability of FG emulsions, maintaining their integrity and improving functional properties under heat treatment. These findings offer valuable insights for the formulation of thermally stable emulsions, presenting promising opportunities for innovative applications in the food industry. © 2024 Society of Chemical Industry.

Mechanism on microbial transglutaminase and Tremella fuciformis polysaccharide-mediated modification of lactoferrin: Development of functional food

Lactoferrin (LF) with various biological functions demonstrates great application potential. However, its application was restricted by its poor gelation and instability. The aim of this work was to explore the effect of microbial transglutaminase (MTGase) and Tremella fuciformis polysaccharide (TP) on the functional properties of LF. The formation of a self-supporting LF gel could be induced by MTGase through generating covalent crosslinks between the LF protein molecules. Meanwhile, TP was introduced into the gel system to improve the strength of LF-TP composite gels by enhancing non-covalent interactions such as hydrogen bond and electrostatic interactions during gel formation. Additionally, the LF-TP composite gel exhibited outstanding functional characteristics such as gastrointestinal digestive stability and antioxidant property. This work clarified the mechanism on MTGase and TP-mediated modification of lactoferrin, offered a novel strategy to increase the functional characteristics of LF, and enlarged the application range of LF and TP.

Integrated ultrasonic-transglutaminase modification of lesser mealworm protein isolate: A pioneering cobalamin delivery vehicle in gluten-free breads

A combined approach of microbial transglutaminase (MTGase) crosslinking and high-intensity ultrasound (HIU) was implemented to improve the physicochemical, rheological, structural, and thermal properties, as well as the targeted release of vitamin B12 of lesser mealworm protein isolate (LMPI)-based gels. Prolonging HIU to 60 min significantly reduced LMPIs' size, polydispersity, zeta-potential, and fluorescence intensity while increasing surface hydrophobicity, free amino (FAGs), and sulfhydryl (FSGs) groups. The MTGase-catalyzed LMPI gels effectively decreased the content of FAGs and FSGs. LMPI gels from 60 and 75 min HIU and MTGase catalysis exhibited a shear-thinning flow behavior, superior thermal stability, and improved water retention and gel strength with the most controlled release of vitamin B12 during in vitro simulated gastrointestinal digestion. Incorporating freeze-dried gel powders from 60 min HIU-treated MTGase-catalyzed LMPI and pea protein isolate into the dough of a new gluten-free bread improved physicochemical, textural, and sensory properties, with notable vitamin B12 retention rate.

A thermally reversible injectable adhesive for intestinal tissue repair and anti-postoperative adhesion

Intestine damage is an acute abdominal disease that usually requires emergency sealing. However, traditional surgical suture not only causes secondary damage to the injured tissue, but also results in adhesion with other tissues in the abdominal cavity. To this end, a thermally reversible injectable gelatin-based hydrogel adhesive (GTPC) is constructed by introducing transglutaminase (TGase) and proanthocyanidins (PCs) into a gelatin system. By reducing the catalytic activity of TGase, the density of covalent and hydrogen bond crosslinking in the hydrogel can be regulated to tune the sol-gel transition temperature of gelatin-based hydrogels above the physiological temperature (42 °C) without introducing any synthetic small molecules. The GTPC hydrogel exhibits good tissue adhesion, antioxidant, and antibacterial properties, which can effectively seal damaged intestinal tissues and regulate the microenvironment of the damaged site, promoting tissue repair and regeneration. Intriguingly, temperature-induced hydrogen bond disruption and reformation confer the hydrogel with asymmetric adhesion properties, preventing tissue adhesion when applied in vivo. Animal experiment outcomes reveal that the GTPC hydrogel can seal the damaged intestinal tissue firmly, accelerate tissue healing, and efficiently prevent postoperative adhesion.

Enhanced environmental stress resistance and functional properties of the curcumin-shellac nano-delivery system: Anti-flocculation of poly-γ-glutamic acid

Curcumin was widely designed as nanoparticles to remove application restrictions. The occurrence of flocculation is a primary factor limiting the application of the curcumin nano-delivery system. To enhance the environmental stress resistance and functional properties of shellac-curcumin nanoparticles (S-Cur-NPs), γ-polyglutamic acid (γ-PGA) was utilized as an anti-flocculant. The encapsulation efficiency and loading capacity of S-Cur-NPs were also improved with γ-PGA incorporation. FTIR and XRD analysis confirmed the presence of amorphous characteristics in S-Cur-NPs and the combination of γ-PGA and shellac was driven by hydrogen bonding. The hydrophilic, thermodynamic, and surface potential of S-Cur-NPs was improved by the incorporation of γ-PGA. This contribution of γ-PGA on S-Cur-NPs effectively mitigated the flocculation occurrence during heating, storage, and in-vitro digestive treatment. Furthermore, it was revealed that γ-PGA enhanced the antibacterial and antioxidant properties of S-Cur-NPs and effectively protected the functional activity against heating, storage, and in-vitro digestion. Release studies conducted in simulated gastrointestinal fluids revealed that S-Cur-NPs have targeted intestinal release properties. Overall, the design of shellac with γ-PGA was a promising strategy to relieve the application stress of shellac and curcumin in the food industry.

Rheology, physicochemical properties, and microstructure of fish gelatin emulsion gel modified by γ-polyglutamic acid

In this work, the effect of the addition of γ-polyglutamic acid (γ-PGA) on the rheology, physicochemical properties, and microstructure of fish gelatin (FG) emulsion gel was investigated. Samples of the emulsion gel were evaluated for rheological behavior and stability prior to gelation. The mechanical properties and water-holding capacity (WHC) of the emulsion were determined after gelation. The microstructure of the emulsion gel was further examined using confocal laser scanning microscopy (CLSM). The results indicated a gradual increase in the apparent viscosity and gelation temperature of the emulsion at a higher concentration of γ-PGA. Additionally, frequency scan results revealed that on the addition of γ-PGA, FG emulsion exhibited a stronger structure. The emulsion containing 0.1% γ-PGA exhibited higher stability than that of the control samples. The WHC and gel strength of the emulsion gel increased on increasing the γ-PGA concentration. CLSM images showed that the addition of γ-PGA modified the structure of the emulsion gel, and the droplets containing 0.1% γ-PGA were evenly distributed. Moreover, γ-PGA could regulate the droplet size of the FG emulsion and its size distribution. These findings suggest that the viscoelasticity and structure of FG emulsion gels could be regulated by adjusting the γ-PGA concentration. The γ-PGA-modified FG emulsion gel also exhibited improved rheology and physicochemical properties. The results showed that γ-PGA-modified FG emulsion gel may find potential applications in food, medicine, cosmetics, and other industries.

Enhancing the Gelation Behavior of Transglutaminase-Induced Soy Protein Isolate(SPI) through Ultrasound-Assisted Extraction

Gelation, as an important functional property of soy protein isolate (SPI), can be improved by some green technologies in food manufacturing, including ultrasound, ultrahigh pressure and microwave treatments. This work investigated the effect of an alkaline solubilisation step in SPI extraction combined with sonication on protein properties. The TGase-induced gel of the modified SPI was prepared to explore the effect of ultrasound on gel properties, including structures, strength, water-holding capacity and rheological properties. Additionally, the differences between traditional ultrasound modification of SPI and current modification methods were analyzed. The results showed that the ultrasonication-assisted extraction method could result in a significant increase in extraction rate from 24.68% to 42.25%. Moreover, ultrasound-assisted modification of SPI gels induced with transglutaminase (TGase) exhibited significant improvement in mechanical properties, such as texture, water-holding capacity and rheological properties, In particular, SPI extracted at 400 W ultrasound intensity for 180 s showed the best overall performance in terms of gel properties. Our method efficiently uniformizes gel structure, enhancing mechanical properties compared to conventional ultrasound methods, which reduced energy consumption and costs. These findings provide insights into the production of high-gelation SPI in food manufacturing.

Effects of Transglutaminase Concentration and Drying Method on Encapsulation of Lactobacillus plantarum in Gelatin-Based Hydrogel

Lactobacillus plantarum is a kind of probiotic that benefits the host by regulating the gut microbiota, but it is easily damaged when passing through the gastrointestinal tract, hindering its ability to reach the destination and reducing its utilization value. Encapsulation is a promising strategy for solving this problem. In this study, transglutaminase (TGase)-crosslinked gelatin (GE)/sodium hexametaphosphate (SHMP) hydrogels were used to encapsulate L. plantarum. The effects of TGase concentration and drying method on the physiochemical properties of the hydrogels were determined. The results showed that at a TGase concentration of 9 U/gGE, the hardness, chewiness, energy storage modulus, and apparent viscosity of the hydrogel encapsulation system were maximized. This concentration produced more high-energy isopeptide bonds, strengthening the interactions between molecules, forming a more stable three-dimensional network structure. The survival rate under the simulated gastrointestinal conditions and storage stability of L. plantarum were improved at this concentration. The thermal stability of the encapsulation system dried via microwave vacuum freeze drying (MFD) was slightly higher than that when dried via freeze drying (FD). The gel structure was more stable, and the activity of L. plantarum decreased more slowly during the storage period when dried using MFD. This research provides a theoretical basis for the development of encapsulation technology of probiotics.

Complex Modification Orders Alleviate the Gelling Weakening Behavior of High Microbial Transglutaminase (MTGase)-Catalyzed Fish Gelatin: Gelling and Structural Analysis

In this paper, the effects of different modification orders of microbial transglutaminase (MTGase) and contents of pectin (0.1-0.5%, w/v) on the gelling and structural properties of fish gelatin (FG) and the modification mechanism were studied. The results showed that the addition of pectin could overcome the phenomenon of high-MTGase-induced lower gelling strength of gelatin gels. At a low pectin content, the modification sequences had non-significant influence on the gelling properties of modified FG, but at a higher pectin content (0.5%, w/v), P0.5%-FG-TG had higher gel strength (751.99 ± 10.9 g) and hardness (14.91 ± 0.33 N) values than those of TG-FG-P0.5% (687.67 ± 20.98 g, 12.18 ± 0.45 N). Rheology analysis showed that the addition of pectin normally improved the gelation points and melting points of FG. The structural results showed that the fluorescence intensity of FG was decreased with the increase in pectin concentration. Fourier transform infrared spectroscopy analysis indicated that the MTGase and pectin complex modifications could influence the secondary structure of FG, but the influenced mechanisms were different. FG was firstly modified by MTGase, and then pectin (P-FG-TG) had the higher gelling and stability properties.

Physicochemical Characterization of Chitosan/Poly-γ-Glutamic Acid Glass-like Materials

This paper sets up a new route for producing non-covalently crosslinked bio-composites by blending poly-γ-glutamic acid (γ-PGA) of microbial origin and chitosan (CH) through poly-electrolyte complexation under specific experimental conditions. CH and two different molecular weight γ-PGA fractions have been blended at different mass ratios (1/9, 2/8 and 3/7) under acidic pH. The developed materials seemed to behave like moldable hydrogels with a soft rubbery consistency. However, after dehydration, they became exceedingly hard, glass-like materials completely insoluble in water and organic solvents. The native biopolymers and their blends underwent comprehensive structural, physicochemical, and thermal analyses. The study confirmed strong physical interactions between polysaccharide and polyamide chains, facilitated by electrostatic attraction and hydrogen bonding. The materials exhibited both crystalline and amorphous structures and demonstrated good thermal stability and degradability. Described as thermoplastic and saloplastic, these bio-composites offer vast opportunities in the realm of polyelectrolyte complexes (PECs). This unique combination of properties allowed the bio-composites to function as glass-like materials, making them highly versatile for potential applications in various fields. They hold potential for use in regenerative medicine, biomedical devices, food packaging, and 3D printing. Their environmentally friendly properties make them attractive candidates for sustainable material development in various industries.

Concentration Selection of Biofriendly Enzyme-Modified Gelatin Hydrogels for Periodontal Bone Regeneration

Periodontitis is challenging to cure radically due to its complex periodontal structure and particular microenvironment of dysbiosis and inflammation. However, with the assistance of various materials, cell osteogenic differentiation could be improved, and the ability of hard tissue regeneration could be enhanced. This study aimed to explore the appropriate concentration ratio of biofriendly transglutaminase-modified gelatin hydrogels for promoting periodontal alveolar bone regeneration. Through a series of characterization and cell experiments, we found that all the hydrogels possessed multi-space network structures and demonstrated their biocompatibility. In vivo and in vitro osteogenic differentiation experiments also confirmed that the group 40-5 (transglutaminase-gelatin concentration ratio) possessed a favorable osteogenic potential. In summary, we conclude that such hydrogel with a 40-5 concentration is most conducive to promoting periodontal bone reconstruction, which might be a new route to deal with the dilemma of clinical periodontal treatment.

A Review of the Mechanism, Properties, and Applications of Hydrogels Prepared by Enzymatic Cross-linking

Hydrogels, as biological materials, are widely used in food, tissue engineering, and biomedical applications. Nevertheless, many issues remain in the preparation of hydrogels by physical and chemical methods, such as low bioaffinity, weak mechanical properties, and unstable structures, which also limit their applications in other fields. However, the enzymatic cross-linking method has the advantages of high catalytic efficiency, mild reaction conditions, and the presence of nontoxic substances. In this review, we evaluated the chemical, physical, and biological methods of preparing hydrogels and introduced three common cross-linking enzymes and their principles for preparing hydrogels. This review introduced the applications and properties of hydrogels prepared by the enzymatic method and also provided some suggestions regarding the current situation and future development of hydrogels prepared by enzymatic cross-linking.

Comparative investigations of various modification methods on the gelling, rheological properties and mechanism of fish gelatin

In this study, κ-carrageenan(κC) and Transglutaminase (TG) were used to modify fish gelatin (FG). Three types of modified gelatin groups FG-κC, FG-TG and FG-κC-TG were prepared. The results showed that the gel strength and textural properties of FG gels were greatly enhanced by κC modification and κC-TG complex modification, whilst pure TG modification weakened the gelling properties. And the pure 0.1 % κC modified FG had the highest gel strength and hardness, respectively. Rheological behavior showed that the complex modified FG samples had the highest viscosity, gelling points, melting points and G'∞. Fourier infrared spectra and LF-NMR analysis showed that κC and κC-TG modification respectively improved the contents of hydrogen and isopeptide that decreased the water mobility but stabilized the helical structure of gelatin gels. Fluorescence intensity showed that three types of modification decreased fluorescence intensity. While, the formation of aggregates and denser gel networks decreased in vitro digestibility of FG.

Effect of High-Intensity Ultrasound Pretreatment on the Properties of the Transglutaminase (TGase)-Induced β-Conglycinin (7S) Gel

In this study, we investigated the effects of different high-intensity ultrasound (HIU) pretreatment times (0-60 min) on the structure of β-conglycinin (7S) and the structural and functional properties of 7S gels induced by transglutaminase (TGase). Analysis of 7S conformation revealed that 30 min HIU pretreatment significantly induced the unfolding of the 7S structure, with the smallest particle size (97.59 nm), the highest surface hydrophobicity (51.42), and the lowering and raising of the content of the α-helix and β-sheet, respectively. Gel solubility showed that HIU facilitated the formation of ε-(γ-glutamyl)lysine isopeptide bonds, which maintain the stability and integrity of the gel network. The SEM revealed that the three-dimensional network structure of the gel at 30 min exhibited filamentous and homogeneous properties. Among them, the gel strength and water-holding capacity were approximately 1.54 and 1.23 times higher than those of the untreated 7S gels, respectively. The 7S gel obtained the highest thermal denaturation temperature (89.39 °C), G', and G″, and the lowest tan δ. Correlation analysis demonstrated that the gel functional properties were negatively correlated with particle size and the α-helix, while positively with Ho and β-sheet. By contrast, gels without sonication or with excessive pretreatment showed a large pore size and inhomogeneous gel network, and poor properties. These results will provide a theoretical basis for the optimization of HIU pretreatment conditions during TGase-induced 7S gel formation, to improve gelling properties.

Development of soy protein isolate/sodium carboxymethyl cellulose synbiotic microgels by double crosslinking with transglutaminase and aluminum chloride for delivery system of Lactobacillus acidophilus

This study was carried out to develop soy protein isolate (SPI)/sodium carboxymethyl cellulose (NaCMC) synbiotic microgels by applying a double-crosslinking technique using transglutaminase and different concentrations of AlCl₃ (0, 6, 7, 8 %) and also by adding Lactobacillus acidophilus (L. acidophilus) and pectic oligosaccharide. Synbiotic microgels crosslinked using 8 % AlCl₃ (SPI/NaCMC-Al³⁺₈ microgels) showed the highest encapsulation efficiency (92 %). The double-crosslinked microgels exhibited a smooth surface as proved by SEM. FT-IR, XRD, and DSC analyses showed the possible interaction within matrices and demonstrated the higher thermal stability of synbiotic microgels prepared using a higher concentration of AlCl₃. All in all, after exposure to simulated digestion fluid, heat treatment (72 °C, 15 s), and refrigerated storage, more cells in double-crosslinked microgels survived compared to single-crosslinked microgels. In particular, probiotic viability was highest in SPI/NaCMC-Al³⁺₈ microgels. These results indicate that the SPI/NaCMC-Al³⁺₈ microgels developed in this study can effectively protect L. acidophilus against the external environment.

Curcumin-Loaded Self-Assembly Constructed by Octenylsuccinate Fish (Cyprinus carpio L.) Scale Gelatin: Preparation and Characterization

Curcumin loaded octenylsuccinate fish scale gelatin (OFSG) was prepared in this study, to explore the potential of FSG for delivering hydrophobic nutrients. The effects of molecule weight (M_w, 22,677-369 g/mol) and degree of substitution (DS, 0-0.116) on the curcumin loading efficiency (CLE, μg/mL) of OFSG (6.98-26.85 mg/mL) were evaluated. The expose of interior hydrophobic groups in FSG and increased intermolecular hydrophobic area contributed to the loading of curcumin in two phases, respectively. The interaction between OFSG and curcumin showed a decreased absorption in FTIR and an increased crystallinity in XRD. The loading of curcumin into OFSG caused a significant decrease of the particle size (from 350-12,070 to 139-214 nm), PDI (from 0.584-0.659 to 0.248-0.347) and ζ-potential (-12.2 or -11.4 to -21.0 or -20.3). OFSG showed a significantly higher stability and lower release of curcumin than FSG at the end of the simulated gastrointestinal digestion. Thus, OFSG showed great potential in the construction of a carrier for hydrophobic nutrients.

Combined morphological and multi-omics analyses to reveal the developmental mechanism of Zanthoxylum bungeanum prickles

Zanthoxylum bungeanum Maxim. as an important economic forest, its epidermis bears prickles which complicate the harvesting process and increase the labor costs. To explore the developmental mechanism of prickles, three varieties of Zanthoxylum bungeanum (PZB, SZB, GSZB) were selected for morphological and multi-omics analyses. The absorption spectra of prickles and stems were detected using Fourier-transform infrared spectroscopy (FTIR), and they were found different at 1617, 1110, 3319, and 1999 cm^-1. The morphology of prickles and stems were observed using light microscopy and transmission electron microscopy (TEM). The growth direction of cells on the prickle side and stem side were perpendicular to each other, and there was a resembling abscission zone (RAZ) between them. The vacuolar deposits of prickle cells were much more than stem cells, indicating that the lignification degree of prickles was higher than stems. In addition, 9 candidate genes (ZbYABBY2, ZbYABBY1, ZbYABBY5, ZbWRKY, ZbLOG5, ZbAZG2, ZbGh16, ZbIAA33, and ZbGh16X1) were screened out and validated base on transcriptome and qRT-PCA. As well as, 30 key metabolites were found related to prickle development base on metabolome analysis. Among them, 4-hydroxy-2-oxopentanoate, trans-2-hydroxy-cinnamate, trans-cinnamate, polyhydroxy-fatty acid, 10,16-dihydroxypalmitate, cinnamic acid were related to the biosynthesis of cutin, suberine and wax. Indole-3-acetate, tryptamine, anthranilate, fromylanthranilate, N6-(delta2-isopentenyl)-adenine were related to plant hormone signal transduction. Generally, this is the first study to reveal the developmental mechanism of prickles. The results of this study lay the foundation for the breeding of non-prickle Zanthoxylum bungeanum.

Rheological properties of fish (Sparus aurata) skin gelatin modified by agricultural wastes extracts

In this study, fish skin gelatin (FG) obtained from sea bream (Sparus aurata) was evaluated as an alternative to mammalian gelatin. Improvement in rheological properties of FG was attempted with addition of grape pomace (GP), pomegranate peel (PP), and green tea (GT) extracts, all of which are agricultural wastes rich in phenolic components. These additives were added at ratios of 20%, 13.3%, 10%, and 6.7% to determine the best formulation. Melting and gelling temperatures, k_gel, gel strength, and t_model values of samples were measured. 20% GP added fish gelatin (OG) had optimum rheological properties. Melting temperatures of BG, OG, and FG were 31.64 ± 0.28, 33.80 ± 0.54, 25.78 ± 0.24 °C, respectively. The addition of GP caused a 14% increase in T_g by increasing the intermolecular interactions of FG. GP is important in that it provides functional properties and structural improvement of FG, making it an alternative to BG and facilitating its use in confectionery industry.

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.

Rheological properties and interactions of fish gelatin-κ-carrageenan polyelectrolyte hydrogels: The effects of salt

This study mainly explored the effects of low-concentration salts (0.1, 0.5 mM NaCl and Na₂ SO₄ ) on the gel, rheological and structural properties of fish gelatin (FG)-κ-carrageenan (κC) polyelectrolyte hydrogels. The results showed that κC could increase the gel strength, hardness, and chewiness of the FG-κC polyelectrolyte hydrogels, while the addition of salts had a negative effect. The rheological behaviors showed that the addition of salts reduced the apparent viscosity, gel, and melting points of the FG-κC polyelectrolyte hydrogels. Compared with NaCl, Na₂ SO₄ -treated FG-κC had lower gel strength, hardness, viscosity, gelation, and melting points, while the addition of salts increased the fluorescence intensity by unfolding FG molecules. The secondary structure analysis results showed that the addition of NaCl and Na₂ SO₄ decreased α-helix and β-sheet contents of FG-κC by destroying the hydrogen bond of FG-κC.