Research progress on polysaccharide/protein hydrogels: Preparation method, functional property and application as delivery systems for bioactive ingredients

Effect of sodium alginate block type on the physicochemical properties and curcumin release behavior of quaternized chitosan-oxidized sodium alginate Schiff base hydrogels

Controlling bioactive ingredients release by modulating the 3D network structure of cross-linked hydrogels is important for functional food development. Hereby, oxidized sodium alginate (OSA) with varying aldehyde contents was formed by periodate oxidation of sodium alginate (SA) with different β-d-mannuronic acid (M) and α-l-guluronic acid (G) ratios (M/G = 1:2, 1:1, and 2:1) and its structure was characterized. Moreover, hydrogels were prepared via Schiff base and electrostatic interactions between quaternized chitosan (QCS) and OSA. The properties of hydrogels such as microstructure, thermal stability, swelling and controlled release were investigated. The results showed that OSA with M/G = 1:2 had the highest content of aldehyde groups, and the hydrogel formed by it and QCS had higher thermal stability and a denser network structure with the lowest equilibrium swelling rate, which could better control the release of curcumin. Additionally, it had good self-healing and can recover rapidly after the rupture of its network structure.

Gel Properties and Protein Structures of Minced Pork Prepared with κ-Carrageenan and Non-Meat Proteins

Problems with minced pork include water release and low gel strength. This study aimed to investigate the effect of treatments with κ-carrageenan (κ-CAR), egg white powder (EWP), wheat gluten (WG), soy isolate protein (SPI), and a combination of these treatments on the gel properties and protein structures of minced pork. The cooking loss and trapped water within minced pork increased when additives were incorporated; in particular, the SPI group reached 1.31 ± 0.01% and 91.42 ± 0.20%. The hardness and chewiness of minced pork reached their maximum values (38.91 ± 0.80 N, 14.73 ± 0.41 N) when the WG was added. The κ-CAR/WG-minced pork gel network structure was the densest and most stable, characterized by increased hydrophobic interactions, disulfide bonds in the mince gel, and enthalpy value. The α-helix content with κ-CAR/WG treatment decreased from 27% to 7.8%, transforming into other secondary structures. This suggests that the addition of κ-CAR/WG can be a more effective combination for improving the quality of minced pork.

Formation of pH-responsive hydrogel beads and their gel properties: Soybean protein nanofibers and sodium alginate

Hydrogel beads prepared from protein nanofibers are popular because of their safety, sleek appearance, and protection of biologically active substances. However, extreme external environmental variations, such as pH and temperature, can limit their practical application. To meet the application requirements of hydrogel beads in different environments, non-covalent mixtures of CaCl2 cross-linked soybean protein nanofibers (SNF) and sodium alginate (SA) were used to prepare hydrogel beads. In the present study, the hardness (782.48 g) and elasticity of hydrogel beads formed at SNF/SA = 7:3 and CaCl2 concentration of 0.1 mol/L were the maximum. Furthermore, the water content and pH swelling also reached a peak (98.68 %, 43.85 g/g) due to the best morphology and regular internal network structure. Meanwhile, the pH-responsive hydrogel beads with added anthocyanins were able to respond to the ambient pH under different temperatures and pH conditions and maintained color stability during 96 h of storage (ΔE < 5). In this experiment, a pH-responsive hydrogel bead based on soybean protein nanofiber (SNF) and sodium alginate (SA) was prepared by simple ionic crosslinking. It provides a theoretical and experimental basis for the future application of plant protein nanofibers as pH-responsive hydrogel materials.

Composite Hydrogel of Poly(vinyl alcohol) Loaded by Citrus hystrix Leaf Extract, Chitosan, and Sodium Alginate with In Vitro Antibacterial and Release Test

Citrus hystrix leaves have been used traditionally as a spice, a traditional medicine for respiratory and digestive disorders, and a remedy for bacterial infections. This study reports on the synthesis of composite hydrogels using the freeze-thaw method with poly(vinyl alcohol) (PVA) as the building block loaded by C. hystrix leaf extract (CHLE). Additionally, chitosan (CS) and sodium alginate (SA) were also loaded, respectively, to increase the antibacterial activity and to control the extract release of the composite hydrogels. The combinations of the compositions were PVA, PVA/CHLE, PVA/CHLE/CS, PVA/CHLE/SA, and PVA/CHLE/SA/CS. The internal morphology of the hydrogels shows some changes after the PVA/CHLE hydrogel was loaded by CS, SA, and SA/CS. The analysis of the Fourier transform infrared (FTIR) spectra confirmed the presence of PVA, CHLE, CS, and SA in the composite hydrogels. From the X-ray diffraction (XRD) characterization, it was shown that the composite hydrogels maintained their semicrystalline properties with decreasing crystallinity degree after being loaded by CS, SA, and SA/CS, as also supported by differential scanning calorimetry (DSC) characterization. The compressive strength of the PVA/CHLE hydrogel decreases after the loading of CS, SA, and SA/CS, so that it becomes more elastic. Despite being loaded in the composite hydrogels, the CHLE retained its antibacterial activity, as evidenced in the in vitro antibacterial test. The loading of CS succeeded in increasing the antibacterial activity of the composite hydrogels, while the loading of SA resulted in the decrease of the antibacterial activity. The release of extract from the composite hydrogels was successfully slowed down after the loading of CS, SA, and SA/CS, resulting in a controlled release following the pseudo-Fickian diffusion. The cytotoxic activity test proved that all hydrogel samples can be used safely on normal cells up to concentrations above 1000 μg/mL.

Towards superior biopolymer gels by enabling interpenetrating network structures: A review on types, applications, and gelation strategies

Gels derived from single networks of natural polymers (biopolymers) typically exhibit limited physical properties and thus have seen constrained applications in areas like food and medicine. In contrast, gels founded on a synergy of multiple biopolymers, specifically polysaccharides and proteins, with intricate interpenetrating polymer network (IPN) structures, represent a promising avenue for the creation of novel gel materials with significantly enhanced properties and combined advantages. This review begins with the scrutiny of newly devised IPN gels formed through a medley of polysaccharides and/or proteins, alongside an introduction of their practical applications in the realm of food, medicine, and environmentally friendly solutions. Finally, based on the fact that the IPN gelation process and mechanism are driven by different inducing factors entwined with a diverse amalgamation of polysaccharides and proteins, our survey underscores the potency of physical, chemical, and enzymatic triggers in orchestrating the construction of crosslinked networks within these biomacromolecules. In these mixed systems, each specific inducer aligns with distinct polysaccharides and proteins, culminating in the generation of semi-IPN or fully-IPN gels through the intricate interpenetration between single networks and polymer chains or between two networks, respectively. The resultant IPN gels stand as paragons of excellence, characterized by their homogeneity, dense network structures, superior textural properties (e.g., hardness, elasticity, adhesion, cohesion, and chewability), outstanding water-holding capacity, and heightened thermal stability, along with guaranteed biosafety (e.g., nontoxicity and biocompatibility) and biodegradability. Therefore, a judicious selection of polymer combinations allows for the development of IPN gels with customized functional properties, adept at meeting precise application requirements.

Chocolates, compounds and spreads: A review on the use of oleogels, hydrogels and hybrid gels to reduce saturated fat content

This study is a bibliometric analysis and literature review on the use of oleogels (OGs), hydrogels (HGs) and hybrid gels (HYGs) in chocolate, compounds and spreads with the aim of reducing the saturated fat in these products. The articles were selected by analyzing titles, keywords and abstracts in the Web of Science (WoS), Scopus and Google Scholar databases. Supplementary documents were obtained from government sources, including patent registrations. The theoretical and practical aspects were critically analyzed, highlighting the main points of agreement and disagreement between the authors. The results revealed a lack of regulations and official guidelines that widely allow the use of OGs, HGs and HYGs in chocolate confectionery products. The type and characteristics of raw materials affect the properties of products. Replacing cocoa butter (CB) with OGs, HGs or HYGs also affects texture, melting point and behavior, and nutritional aspects. These substitutions can result in products with better sensory acceptance and health benefits, such as reducing saturated fat and promoting cardiovascular health. However, it is important to find the ideal combination and proportions of components to obtain the desired properties in the final products.

Emulsion for stabilizing β-carotene and curcumin prepared directly using a continuous phase of polysaccharide-rich Schizophyllum commune fermentation broth

In this study, we examined the effect of Schizophyllum commune fermentation broth (SCFB) rich in polysaccharides (SCFP) on the stability and bioaccessibility of β-carotene and curcumin. An SCFB-stabilized oil-in-water (o/w) emulsion (SCFBe) was prepared using SCFB as the continuous phase, and then evaluated for storage stability using an SCFP-based emulsion (SCFPe) as the control. The findings revealed that SCFBe is more stable at 60 °C than SCFPe, and stratification or droplet size varied at differing pH levels (3-9) and concentrations of Na+ (0.1-0.5 M) and Ca2+ (0.01-0.05 M). Since the absolute value of the zeta potential of SCFBe is much lower at 60 °C than that at 4 °C and 25 °C, a higher temperature (60 °C) may enhance the reactivity of polysaccharides and proteins in SCFB to improve the stability of SCFBe. Both the protective impact of SCFB on functional food molecules and their capacity to block lipid oxidation increased as polysaccharide content improved. The bioaccessibility of β-carotene after in vitro simulated gastrointestinal digestion is 11.18 %-12.28 %, whereas that of curcumin is 31.64 %-33.00 %. By fermenting edible and medicinal fungi in liquid, we created a unique and environmentally friendly approach for getting food-grade emulsifiers without extraction.

Preparations, application of polysaccharide-protein nanoparticles and their assembly at the oil-water interface

With the development of nanotechnology, nanoparticles have played an important role in pharmaceuticals, foods and materials, in particular, protein/polysaccharide based composite nanoparticles have received attention from researchers for safety and green production. This paper summarized in detail the preparation methods, applications of protein/polysaccharide nanoparticles (PPNPs) in recent years, especially the mechanism of stabilizing the oil-water interface. Currently, the polysaccharides applied are more traditional, such as chitosan, pectin and carboxymethyl cellulose, so there is still a lot of room for the development of raw materials that can be used to prepare PPNPs. Based on this, we also proposed three promising polysaccharides: seaweed polysaccharide, lycium barbarum polysaccharide and lactobacillus exopolysaccharides, describing their characteristics as well as their application prospects, this article can serve as a reference for interested researchers.

Protein/polysaccharide-based hydrogels loaded probiotic-mediated therapeutic systems: A review

The natural characteristics of protein/polysaccharide-based hydrogels, as a potential drug delivery platform, have attracted extensive attention. Probiotics have attracted renewed interest in drug research because of their beneficial effects on host health. The idea of using probiotics loaded on protein/polysaccharide-based hydrogels as potential drugs to treat different diseases has been put forward and shows great prospects. Based on this, in this review, we highlight the design strategy of hydrogels loaded probiotic-mediated therapy systems and review the potential diseases that have been proved to be treatable in the laboratory, including promoting wound healing and improving intestinal health and vaginal health, and discuss the challenges existing in the current design.

Effects of tandem fermentation of edible mushroom and L. plantarum on sensory, polysaccharide, vitamin C, and γ-aminobutyric acid of Rosa roxburghii Tratt and coix seed beverage

A new Rosa roxburghii Tratt (RRT) and coix seed (CS) beverage rich in multi-active ingredients was developed. Edible mushrooms and L. plantarum were selected for fermentation in stages. Some physicochemical properties, γ-aminobutyric acid (GABA), polysaccharides and sensory were studied during the T. versicolor and L. plantarum fermentation. T. versicolor increased the free amino acid through enzymatic protein digestion in the early growth stage and used these amino acids to synthesize its bacteriophage protein. T. versicolor and L. plantarum increased the polysaccharide and GABA of the fermentation broth. Vitamin C was retained as much as possible, with a slight loss occurring mainly in the aerobic fermentation stage of T. versicolor. Its less loss in exchange was for a higher value of T. versicolor polysaccharide, protein enhancement, and bitterness reduction. This study provides a reference for the deep processing of Guizhou's unique agricultural products and edible mushroom fermented beverage.

Designing future foods: Harnessing 3D food printing technology to encapsulate bioactive compounds

Bioactive compounds (BCs) provide numerous health benefits by interacting with one or more components of living tissues and systems. However, despite their potential health benefits, most of the BCs have low bioaccessibility and bioavailability, hindering their potential health-promoting activities. The conventional encapsulation techniques are time-consuming and have major limitations in their food applications, including the use of non-food grade chemicals, undesired sensory attributes, and storage stability issues. A cutting-edge, new technique based on 3D printing can assist in resolving the problems associated with conventional encapsulation technologies. 3D food printing can help protect BCs by incorporating them precisely into three-dimensional matrices, which can provide (i) protection during storage, (ii) enhanced bioavailability, and (iii) effective delivery and controlled release of BCs. Recently, various 3D printing techniques and inks have been investigated in order to create delivery systems with different compositions and geometries, as well as diverse release patterns. This review emphasizes the advances in 3D printing-based encapsulation approaches, leading to enhanced delivery systems and customized food formulations.

Flexible Curcumin-Loaded Zn-MOF Hydrogel for Long-Term Drug Release and Antibacterial Activities

Management of chronic inflammation and wounds has always been a key issue in the pharmaceutical and healthcare sectors. Curcumin (CCM) is an active ingredient extracted from turmeric rhizomes with antioxidant, anti-inflammatory, and antibacterial activities, thus showing significant effectiveness toward wound healing. However, its shortcomings, such as poor water solubility, poor chemical stability, and fast metabolic rate, limit its bioavailability and long-term use. In this context, hydrogels appear to be a versatile matrix for carrying and stabilizing drugs due to their biomimetic structure, soft porous microarchitecture, and favorable biomechanical properties. The drug loading/releasing efficiencies can also be controlled via using highly crystalline and porous metal-organic frameworks (MOFs). Herein, a flexible hydrogel composed of a sodium alginate (SA) matrix and CCM-loaded MOFs was constructed for long-term drug release and antibacterial activity. The morphology and physicochemical properties of composite hydrogels were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and mechanical property tests. The results showed that the composite hydrogel was highly twistable and bendable to comply with human skin mechanically. The as-prepared hydrogel could capture efficient CCM for slow drug release and effectively kill bacteria. Therefore, such composite hydrogel is expected to provide a new management system for chronic wound dressings.

Preparation and Characterization of Alginate Hydrogels with High Water-Retaining Capacity

Hydrogels are very attractive materials due to their multifunctional properties. Many natural polymers, such as polysaccharides, are used for the preparation of hydrogels. The most important and commonly used polysaccharide is alginate because of its biodegradability, biocompatibility, and non-toxicity. Since the properties of alginate hydrogel and its application depend on numerous factors, this study aimed to optimize the gel composition to enable the growth of inoculated cyanobacterial crusts for suppressing the desertification process. The influence of alginate concentration (0.1-2.9%, m/v) and CaCl₂ concentration (0.4-4.6%, m/v) on the water-retaining capacity was analyzed using the response surface methodology. According to the design matrix, 13 formulations of different compositions were prepared. The water-retaining capacity was defined as the system response maximized in optimization studies. The optimal composition of hydrogel with a water-retaining capacity of about 76% was obtained using 2.7% (m/v) alginate solution and 0.9% (m/v) CaCl₂ solution. Fourier transform infrared spectroscopy was used for the structural characterization of the prepared hydrogels, while the water content and swelling ratio of hydrogels were determined using gravimetric methods. It was concluded that alginate and CaCl₂ concentrations play the most important role regarding the gelation time, homogeneity, water content, and swelling ratio of the hydrogel.

Dipeptide-polysaccharides hydrogels through co-assembly

Self-assembling dipeptide hydrogels are attracting attention in food, materials, and biomedicine. However, there are still limitations such as weak hydrogel properties. Herein, we introduced two types of polysaccharides (Arabic gum and citrus pectin) into an alkyl-chain modified dipeptide (C₁₃-tryptophan-tyrosine (C₁₃-WY)) to generate co-assembled C₁₃-WY-arabic gum and C₁₃-WY-pectin hydrogels. The co-assembled hydrogels exhibited enhanced mechanical properties and stability. The G' value of C₁₃-WY-arabic gum and C₁₃-WY-pectin hydrogels was 3 and 10 times larger than that of C₁₃-WY hydrogel, respectively. The addition of Arabic gum and citrus pectin led to the co-assembly and molecular rearrangement. Moreover, co-assembled hydrogels showed more β-sheet structure and hydrogen bonds. Importantly, the self-/co-assembled hydrogels showed low cytotoxicity. We utilized these hydrogels for the encapsulation of docetaxel and they showed a high embedding rate and slow-release. Our findings provide a novel strategy for the development of stable supramolecular peptide hydrogels with good biocompatibility through simple co-assembly.

Engineering Cell Microenvironment Using Nanopattern-Derived Multicellular Spheroids and Photo-Crosslinked Gelatin/Hyaluronan Hydrogels

Cell cultures of dispersed cells within hydrogels depict the interaction of the cell-extracellular matrix (ECM) in 3D, while the coculture of different cells within spheroids combines both the effects of cell-cell and cell-ECM interactions. In this study, the cell co-spheroids of human bone mesenchymal stem cells/human umbilical vein endothelial cells (HBMSC/HUVECs) are prepared with the assistance of a nanopattern, named colloidal self-assembled patterns (cSAPs), which is superior to low-adhesion surfaces. A phenol-modified gelatin/hyaluronan (Gel-Ph/HA-Ph) hydrogel is used to encapsulate the multicellular spheroids and the constructs are photo-crosslinked using blue light. The results show that Gel-Ph/HA-Ph hydrogels with a 5%-to-0.3% ratio have the best properties. Cells in HBMSC/HUVEC co-spheroids are more favorable for osteogenic differentiation (Runx2, ALP, Col1a1 and OPN) and vascular network formation (CD31+ cells) compared to HBMSC spheroids. In a subcutaneous nude mouse model, the HBMSC/HUVEC co-spheroids showed better performance than HBMSC spheroids in angiogenesis and the development of blood vessels. Overall, this study paves a new way for using nanopatterns, cell coculturing and hydrogel technology for the generation and application of multicellular spheroids.

Acid-induced Poria cocos alkali-soluble polysaccharide hydrogel: Gelation behaviour, characteristics, and potential application in drug delivery

Poria cocos alkali-soluble polysaccharide (PCAP), a water-insoluble β-glucan, is the main component of the total dried sclerotia of Poria cocos. However, its gelation behaviour and properties have yet to be comprehensively studied. In this study, an acid-induced physical hydrogel based on natural PCAP is fabricated. The acid-induced gelation in PCAP is explored with respect to the pH and polysaccharide concentration. PCAP hydrogels are formed in the pH range of 0.3-10.5, and the lowest gelation concentration is 0.4 wt%. Furthermore, dynamic rheological, fluorescence, and cyclic voltammetry measurements are performed to elucidate the gelation mechanism. The results reveal that hydrogen bonds and hydrophobic interactions play a dominant role in gel formation. Subsequently, the properties of the PCAP hydrogels are investigated using rheological measurements, scanning electron microscopy, gravimetric analysis, free radical scavenging, MTT assays, and enzyme-linked immunosorbent assays. The PCAP hydrogels exhibit a porous network structure and cytocompatibility, in addition to good viscoelastic, thixotropic, water-holding, swelling, antioxidant, and anti-inflammatory activities. Furthermore, using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behaviour from the PCAP hydrogel is pH dependent. These results indicate the potential of PCAP hydrogels for application in biological medicine and drug delivery.

Seed mucilage-based advanced carrier systems for food and nutraceuticals: fabrication, formulation efficiency, recent advancement, challenges, and perspectives

Seed mucilages are potential sources of natural polysaccharides. They are biodegradable, biocompatible, sustainable, renewable, and safe for human consumption. Due to the desirable physicochemical and functional properties (e.g. gelling, thickening, stabilizing, and emulsifying), seed mucilages have attracted extensive attention from researchers for utilization as a promising material for the development of advanced carrier systems. Seed mucilages have been utilized as natural polymers to improve the properties of various carrier systems (e.g. complex coacervates, beads, nanofibers, and gels) and for the delivery of diverse hydrophilic and lipophilic compounds (e.g. vitamins, essential oils, antioxidants, probiotics, and antimicrobial agents) to achieve enhanced stability, bioavailability, bioactivity of the encapsulated molecules, and improved quality attributes of food products. This review highlights the recent progress in seed mucilage-based carrier systems for food and nutraceutical applications. The main contents include (1) sources, extraction methods, and physicochemical and functional characteristics of seed mucilages, (2) application of seed mucilages for the development of advanced carrier systems, (3) major issues associated with carrier fabrication, and (4) mechanisms of carrier development, latest improvements in carrier formulation, carrier efficiency in the delivery of bioactive agents, and application in food and nutraceuticals. Furthermore, major challenges and future perspectives of seed mucilage-based carriers for a commercial application are discussed.

Effects of κ-carrageenan gum on 3D printability and rheological properties of pork pastes

The effects of κ-carrageenan gum (KG) on the 3D printability and rheological properties of pork pastes were investigated in this study. There were five groups with different levels of KG (0, 2, 4, 6, and 8 g/kg) named as KG-0, KG-2, KG-4, KG-6, and KG-8, respectively. The addition of KG increased the yield stress, viscosity, shear stress, recovery percentage, storage modulus, loss modulus, and initial and average flow forces (P < 0.05). The results of low-field nuclear magnetic resonance analysis revealed that addition of KG reduced T₂₁ and T₂₂ (P < 0.05). The best printing parameters were obtained by accuracy and stability results: printing filling percent, 90%; printing speed, 35 mm⋅s^-1; layer height, 2 mm; nozzle diameter, 1.55 mm, and KG addition level, 6 g/kg. KG addition improved the hardness, springiness, chewiness, cohesiveness, adhesiveness, and density, respectively (P < 0.05). The results suggested that KG addition improved the rheological properties and 3D printability of the pork pastes.

Fabrication of high strength cold-set sodium alginate/whey protein nanofiber double network hydrogels and their interaction with curcumin

Enhancing the bio-based hydrogels strength is fundamental to extend their engineering applications. In this study, high strength cold-set sodium alginate/whey protein nanofiber (SA/WPN) double network hydrogels were prepared and their interaction with curcumin (Cur) was studied. Our results indicated that the rheological and textural properties of SA/WPN double network hydrogels were enhanced with increasing WPN by forming SA-COO^--Ca²⁺-^-OOC-WPN bridge through electrostatic interactions. The storage modulus (768.2 Pa), hardness (273.3 g), adhesiveness (318.7 g·sec) and cohesiveness (0.464) of SA/WPN50 (WPN concentration of 50 mg/mL) double network hydrogels were 3.75, 2.26, 3.76 and 2.19 times higher than those of SA hydrogels, respectively. Cur was combined with SA/WPN hydrogels through hydrogen bonding, van der Waals forces and hydrophobic interactions with an encapsulation efficiency of 91.6 ± 0.8 %, and the crystalline state was changed after binding. In conclusion, SA/WPN double network hydrogels can be enhanced by the addition of WPN and have potential as carriers for hydrophobic bioactive substances.

Designation and characterization of cold-set egg white protein/dextran sulfate hydrogel for curcumin entrapment

This study aimed to design a cold-set hydrogel of egg white protein (EWP) with good mechanical properties for encapsulating curcumin. Dextran sulfate (DS) and transglutaminase (TGase) were used to control the aggregation and gelation behavior of EWP at preheating step and gelation step, respectively. The optimum soluble protein aggregate size was obtained in the EWP/DS mixture at a mass ratio of 10 under 85 °C preheated (HED₁₀). The presence of TGase further enhanced the cross-linking degree between protein aggregates during the gelation step. The highest gel hardness was found in HED₁₀ hydrogel with TGase, which is almost 10 times the pure EWP gel. Besides, the HED hydrogels effectively slowed down the release rate of curcumin in gastrointestinal digestion. This work provides a theoretical basis for the development of cold-set EWP hydrogel with good mechanical strength by sulfated polysaccharide addition and TGase cross-linking as encapsulation delivery systems.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

pH-responsive in situ gelling properties of thiolated citrus high-methoxyl pectin and its potential gel mechanism

pH-responsive in situ gelling properties of thiolated citrus high-methoxyl pectin (TCHMP) were investigated in this study. The gelation capacity results revealed that the in situ gelation behavior of TCHMP only occurred when the pH value was higher than 6.25. The gel strength increased from 26.63 g to 42.77 g as the pH value increased from 7.4 to 8.9. Rheological measurements confirmed that the apparent viscosity and viscoelasticity of TCHMP were highly dependent on pH value and dialysis time. Compared with the control group, the apparent viscosity of TCHMP dialyzed in phosphate-buffered saline (PBS) of pH 8.9 for 180 min increased 695-fold. During the dialysis process of TCHMP at different pH values (7.4-8.9), the final thiol groups content decreased and the final disulfide bonds content increased with the increase in pH value. This illustrates that the mechanism of in situ gelation is mainly the oxidation of thiol-thiol groups to form disulfide bonds. These results can put forward new insights into the pH-responsive in situ gelling properties of TCHMP and provide a theoretical basis for the application of TCHMP in neutral and alkaline gel systems.

Fabrication and characterization of the H/J-type aggregates astaxanthin/bovine serum albumin/chitosan nanoparticles

Astaxanthin is a natural liposoluble ketocarotenoid with various biological activities. Hydrophobic astaxanthin with C_2h symmetry can self-assembly form H-type aggregates and J-type aggregates in hydrated polar solvents. However, astaxanthin and its aggregates are limited by its water insolubility and chemical instability. Here, the biological macromolecules bovine serum albumin (BSA) and chitosan were chosen as protein-polysaccharides based delivery systems for astaxanthin aggregates by molecular self-assembly method. The precise prepared H-ABC-NPs and J-ABC-NPs suspensions were both near spheres with hydrodynamic size around 281 ± 9 nm and 368 ± 5 nm and zeta potentials around +26 mV and +30 mV, respectively. Two types of astaxanthin aggregates were distinguished, water-dispersible, and stable in nanocarriers through UV-vis spectra observation. The encapsulation efficiency of the astaxanthin in ABC-NPs was above 90 %. Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) analyses indicated that the dominant driving forces of ABC-NPs formation mainly included electrostatic, hydrophobic interactions and hydrogen bonding. These results offer an elegant opportunity for the protein-polysaccharides delivery systems, and provide an important perspective for applying novel water-dispersed astaxanthin aggregates products in nutrition and medicine industry.

Reactive Extrusion-Assisted Process to Obtain Starch Hydrogels through Reaction with Organic Acids

A totally green process based on reactive extrusion was used for the production of cassava starch hydrogels through reaction with two organic crosslinking agents, citric (CA) and tartaric (TA) acids. CA and TA were used at different concentrations (0, 2.5, 5.0, 10.0, 15.0, and 20.0%). Degree of substitution (DS) of hydrogels ranged from 0.023 to 0.365. Fourier transform infrared spectroscopy results showed a new band appearing at 1730 cm−1 associated with ester carbonyl groups. X-ray diffraction indicated that reactive extrusion resulted in the disappearance of diffraction peaks of native starch and samples with lower crystallinity indices ranging from 37% (native starch) to 8–11% in starch hydrogels. Morphology analysis showed that the original granular structure of starch was lost and replaced by a rougher and irregular structure. Water holding capacity values of starch hydrogels obtained by reactive extrusion were superior to those of native starch and the control sample (extruded without the crosslinking agents). Hydrogels obtained with the highest CA or TA concentration (20.0%) resulted in the higher DS and swelling capacities, resulting in samples with 870 and 810% of water retention, respectively. Reactive extrusion was effective in obtaining starch hydrogels by reaction with organic acids.

Strategic developments in the drug delivery of natural product dihydromyricetin: applications, prospects, and challenges

Dihydromyricetin (DHM) is an important natural flavonoid that has attracted much attention because of its various functions such as protecting the cardiovascular system and liver, treating cancer and neurodegenerative diseases, and anti-inflammation effect, etc. Despite its great development potential in pharmacy, DHM has some problems in pharmaceutical applications such as low solubility, permeability, and stability. To settle these issues, extensive research has been carried out on its physicochemical properties and dosage forms to produce all kinds of DHM preparations in the past ten years. In addition, the combined use of DHM with other drugs is a promising strategy to expand the application of DHM. However, although invention patents for DHM preparations have been issued in several countries, the current transformation of DHM research results into market products is insufficient. To date, there is still a lack of deep research into the pharmacokinetics, pharmacodynamics, toxicology, and action mechanism of DHM preparations. Besides, preparations for combined therapy of DHM with other drugs are scarcely reported, which necessitates the development of dosage forms for this application. Apart from medicine, the development of DHM in the food industry is also of great potential. Due to its multiple effects and excellent safety, DHM preparations can be developed for functional drinks and foods. Through this review, we hope to draw more attention to the development potential of DHM and the above challenges and provide valuable references for the research and development of other natural products with a similar structure-activity relationship to this drug.

Insights on Some Polysaccharide Gel Type Materials and Their Structural Peculiarities

Global resources have to be used in responsible ways to ensure the world's future need for advanced materials. Ecologically friendly functional materials based on biopolymers can be successfully obtained from renewable resources, and the most prominent example is cellulose, the well-known most abundant polysaccharide which is usually isolated from highly available biomass (wood and wooden waste, annual plants, cotton, etc.). Many other polysaccharides originating from various natural resources (plants, insects, algae, bacteria) proved to be valuable and versatile starting biopolymers for a wide array of materials with tunable properties, able to respond to different societal demands. Polysaccharides properties vary depending on various factors (origin, harvesting, storage and transportation, strategy of further modification), but they can be processed into materials with high added value, as in the case of gels. Modern approaches have been employed to prepare (e.g., the use of ionic liquids as "green solvents") and characterize (NMR and FTIR spectroscopy, X ray diffraction spectrometry, DSC, electronic and atomic force microscopy, optical rotation, circular dichroism, rheological investigations, computer modelling and optimization) polysaccharide gels. In the present paper, some of the most widely used polysaccharide gels will be briefly reviewed with emphasis on their structural peculiarities under various conditions.

Recent Advances in Smart Hydrogels Prepared by Ionizing Radiation Technology for Biomedical Applications

Materials with excellent biocompatibility and targeting can be widely used in the biomedical field. Hydrogels are an excellent biomedical material, which are similar to living tissue and cannot affect the metabolic process of living organisms. Moreover, the three-dimensional network structure of hydrogel is conducive to the storage and slow release of drugs. Compared to the traditional hydrogel preparation technologies, ionizing radiation technology has high efficiency, is green, and has environmental protection. This technology can easily adjust mechanical properties, swelling, and so on. This review provides a classification of hydrogels and different preparation methods and highlights the advantages of ionizing radiation technology in smart hydrogels used for biomedical applications.

Survivability of probiotics encapsulated in kelp nanocellulose/alginate microcapsules on microfluidic device

Probiotics are living microorganisms that can produce health benefits to the host only when they are ingested in sufficient quantities and reach the intestines active state. However, the external environment that probiotics face for a long time before administration and the low pH environment in the stomach after administration can greatly reduce their activity. In this work, we proposed a simple microfluidic encapsulation strategy to efficiently prepare the probiotics-loaded nanocellulose/alginate delivery system, which can improve the storage stability and gastrointestinal survival rate of probiotics. The microcapsules were found to be monodisperse, and the average particle size was<500 μm by observing the microstructure and macroscopic morphology. The kelp nanocellulose was cross-linked in the microcapsule and formed a dense surface with alginate. Through the simulated gastrointestinal digestion experiment, it was found that the survival of probiotics in microcapsules containing 0.5 % and 1.5 % kelp nanocellulose decreased by 1.77 log CFU/g and 1.65 log CFU/g respectively, which was significantly lower than that of nanocellulose-free microcapsules (3.70 log CFU/g). And all the treated groups could release probiotics above 7 log CFU/g after digesting intestinal juice for 6 h. Furthermore, through the storage experiment, it was found that the microcapsules with 1.5 % kelp nanocellulose could still release 8.07 log CFU/g probiotics after four weeks. The results provide a new strategy for probiotics processing and extensive high-value utilization of marine natural products.

Effect of the molecular structure and mechanical properties of plant-based hydrogels in food systems to deliver probiotics: an updated review

Probiotic products' economic value and market popularity have grown over time as more people discover their health advantages and adopt healthier lifestyles. There is a significant societal and cultural interest in these products known as foods or medicines. Products containing probiotics that claim to provide health advantages must maintain a "minimum therapeutic" level (107-106 CFU/g) of bacteria during their entire shelf lives. Since probiotic bacteria are susceptible to degradation and reduction by physical and chemical conditions (including acidity, natural antimicrobial agents, nutrient contents, redox potential, temperature, water activity, the existence of other bacteria, and sensitivity to metabolites), the most challenging problem for a food manufacturer is ensuring probiotic cells' survival and stability enhancement throughout the manufacturing stage. Currently, the use of plant-based hydrogels for improved and targeted probiotic delivery has gained substantial attention as a potential approach to overcoming the mentioned restrictions. To achieve the best possible results from hydrogels, whether used as a coating for encapsulated probiotics (with the goal of stomach protection) or as carriers for direct encapsulation of live microorganisms should be applied kind of procedures that ensure high bacterial survival during hydrogels application. This paper summarizes polysaccharides, proteins, and lipid-based hydrogels as carriers of encapsulated probiotics in delivery systems, reviews their structures, analyzes their advantages and disadvantages, studies their mechanical characteristics, and draws comparisons between them. The discussion then turns to how the criterion affects encapsulation, applications, and future possibilities.

Polysaccharide-Based Edible Gels as Functional Ingredients: Characterization, Applicability, and Human Health Benefits

Nowadays, edible materials such as polysaccharides have gained attention due to their valuable attributes, especially gelling property. Polysaccharide-based edible gels (PEGs) can be classified as (i) hydrogels, (ii) oleogels and bigels, (iii) and aerogels, cryogels and xerogels, respectively. PEGs have different characteristics and benefits depending on the functional groups of polysaccharide chains (e.g., carboxylic, sulphonic, amino, methoxyl) and on the preparation method. However, PEGs are found in the incipient phase of research and most studies are related to their preparation, characterization, sustainable raw materials, and applicability. Furthermore, all these aspects are treated separately for each class of PEG, without offering an overview of those already obtained PEGs. The novelty of this manuscript is to offer an overview of the classification, definition, formulation, and characterization of PEGs. Furthermore, the applicability of PEGs in the food sector (e.g., food packaging, improving food profile agent, delivery systems) and in the medical/pharmaceutical sector is also critically discussed. Ultimately, the correlation between PEG consumption and polysaccharides properties for human health (e.g., intestinal microecology, "bridge effect" in obesity, gut microbiota) are critically discussed for the first time. Bigels may be valuable for use as ink for 3D food printing in personalized diets for human health treatment. PEGs have a significant role in developing smart materials as both ingredients and coatings and methods, and techniques for exploring PEGs are essential. PEGs as carriers of bioactive compounds have a demonstrated effect on obesity. All the physical, chemical, and biological interactions among PEGs and other organic and inorganic structures should be investigated.

Preparation and Properties of Salecan-Soy Protein Isolate Composite Hydrogel Induced by Thermal Treatment and Transglutaminase

Salecan (Sal) is a novel marine microbial polysaccharide. In the present research, Sal and soy protein isolate (SPI) were adopted to fabricate Sal–SPI composite hydrogel based on a stepwise process (thermal treatment and transglutaminase induction). The effect of Sal concentration on morphology, texture properties, and the microstructure of the hydrogel was evaluated. As Sal concentration varied from 0.4 to 0.6 wt%, hydrogel elasticity increased from 0.49 to 0.85 mm. Furthermore, the internal network structure of Sal–SPI composite hydrogel also became denser and more uniform as Sal concentration increased. Rheological studies showed that Sal–SPI elastic hydrogel formed under the gelation process. Additionally, FTIR and XRD results demonstrated that hydrogen bonds formed between Sal and SPI molecules, inferring the formation of the interpenetrating network structure. This research supplied a green and simple method to fabricate Sal–SPI double network hydrogels.

Egg white protein-based delivery system for bioactive substances: a review

Some bioactive substances in food have problems such as poor solubility, unstable chemical properties and low bioavailability, which limits their application in functional food. Recently, many egg white protein-based delivery carriers have been developed to improve the chemical stability, biological activity and bioavailability of bioactive substances. This article reviewed the structure and properties of several major egg white proteins commonly used to construct bioactive substance delivery systems. Several common carrier types based on egg white proteins, including hydrogels, emulsions, micro/nanoparticles, aerogels and electrospinning were then introduced. The biological functions of common bioactive substances, the limitations, and the role of egg white protein-based delivery systems were also discussed. At present, whole egg white protein, ovalbumin and lysozyme are most widely used in delivery systems, while ovotransferrin, ovomucoid and ovomucin are less developed and applied. Egg white protein-based nanoparticles are currently the most commonly used delivery carriers. Egg white protein-based hydrogels, emulsions, and microparticles are also widely used. Future research on the application of various egg white proteins in developed new delivery systems will provide more choices for the delivery of various bioactive substances.

Recent insights into polysaccharide-based hydrogels and their potential applications in food sector: A review

Hydrogels are ideal for various food applications because of their softness, elasticity, absorbent nature, flexibility, and hygroscopic nature. Polysaccharide hydrogels are particularly suitable because of the hydrophilic nature, their food compatibility, and their non-immunogenic character. Such hydrogels offer a wide range of successful applications such as food preservation, pharmaceuticals, agriculture, and food packaging. Additionally, polysaccharide hydrogels have proven to play a significant role in the formulation of food flavor carrier systems, thus diversifying the horizons of newer developments in food processing sector. Polysaccharide hydrogels are comprised of natural polymers such as alginate, chitosan, starch, pectin and hyaluronic acid when crosslinked physically or chemically. Hydrogels with interchangeable, antimicrobial and barrier properties are referred to as smart hydrogels. This review brings together the recent and relevant polysaccharide research in these polysaccharide hydrogel applications areas and seeks to point the way forward for future research and interventions. Applications in carrying out the process of flavor carrier system directly through their incorporation in food matrices, broadening the domain for food application innovations. The classification and important features of polysaccharide-based hydrogels in food processing are the topics of the current review study.

Complex characterization and formation mechanism of scallop (Patinopecten yessoensis) protein hydrolysates/κ-carrageenan/konjac gum composite gels

The combination of κ-Carrageenan (KC) and konjac gum (KGM) were introduced to examine the impact on gelation and microstructural behaviors of scallop male gonads hydrolysates (SMGHs) and the involvement of intermolecular forces. In terms of G' response of SMGHs/KGM/KC, it obviously enhanced by 3.6- and 108.5-fold than controls of KGM/KC and SMGHs/KC at 0.1 Hz, accompanying increasing melting temperatures from 27.9 (KGM/KC) and 30.0 (SMGHs/KC) to 33.7°C (SMGHs/KGM/KC), respectively. Additionally, SMGHs/KGM/KC with decreasing relaxation time T₂₃ and blue shift of hydroxyl group than controls suggested higher water retention capacity and ordered conformation. Moreover, SMGHs/KGM/KC formed compact networks with thick walls as reflected by cryo-SEM and showed rougher surface with more aggregation as reflected by AFM. Furthermore, electrostatic in couple with hydrophobic interactions were dominant interactions, while hydrogen bonds were involved in subordinately in SMGHs/KGM/KC. PRACTICAL APPLICATION: Scallop (Patinopecten yessoensis) male gonads are always discarded during processing despite high-protein content and edibility. In the current research, scallop male gonad hydrolysates (SMGHs) exhibited gelation behavior, which have a potential role in developing marine source protein as a functional food base such as kamaboko gels, can, sausage and spread and even delivery vehicles for bioactive compounds.

The Layered Encapsulation of Vitamin B2 and β-Carotene in Multilayer Alginate/Chitosan Gel Microspheres: Improving the Bioaccessibility of Vitamin B2 and β-Carotene

This research underlines the potential of alginate multilayered gel microspheres for the layered encapsulation and the simultaneous delivery of vitamin B₂ (VB) and β-carotene (BC). Chitosan was used to improve the stability and controlled release ability of alginate-based gel microspheres. It was shown that a clear multilayered structure possessed the characteristics of pH response, and excellent thermal stability. The sodium alginate concentration and the number of layers had notable effects on mechanical properties and particle size of gel microspheres. Fourier-transform infrared spectroscopy and X-ray diffraction analyses further proved that VB and BC were encapsulated within the gel microspheres. Compared with the three-layer VB-loaded gel microspheres, the total release of VB from the three-layer VB and BC-loaded gel decreased from 93.23% to 85.58%. The total release of BC from the three-layer VB and BC-loaded gel increased from 66.11% to 69.24% compared with three-layer BC-loaded gel. The simultaneous encapsulation of VB and BC in multilayered gel microspheres can markedly improve their bioaccessibility and bioavailability. These results showed the multilayer gel microspheres synthesized herein have potential for applications in the layered encapsulation and simultaneous delivery of various bioactive substances to the intestinal tract.