Production of hybrid gels from polysorbate and gellan gum

Construction of asymmetric dual-layer polysaccharide-based porous structure on multiple sources for potential application in biomedicine

Biomedical materials can produce high efficiency and special behavior with an integrated internal structure. It is possible that changing the structure of biomedical materials could extend and promote the application of eco-friendly and multifunctional biomaterials. However, the instantaneous formation of complex structures between tannic acid (TA) and polysaccharides is disrupted, and the reconstruction of the new porous structure becomes a key issue. Here, we present an innovative one-step forming method for an asymmetric dual-layer porous structure of carboxymethyl chitosan (CC)/sodium alginate (SA)/TA, which can be utilized in various biomedical applications. Even after 6 months of storage, it still demonstrates a range of desirable properties including tailorable performance, efficient antibacterial activity, ultrarapid antioxidant activity, low differential blood clotting index and cytotoxicity. This suggests its potential for regulating and controlling wound bleeding, providing flexible possibilities for potential applications in biomedicine.

Effect of the gelling mechanism on the physical properties of bigels based on whey protein isolate

The effect of the cold-set and heat-set gelling mechanism of whey protein isolate on bigel production was assessed. For this purpose, hydrogel phase was produced with whey protein isolated (10 % w/v) and for oleogel sunflower oil and glycerol monostearate (7.5 % w/v) were used. Bigels were produced by hot emulsification of different hydrogel:oleogel ratios (from 90:10 up to 10:90). For cold-set bigels (CSB) NaCl (200 mM) was added to the aqueous phase prior to the emulsification and the emulsion was cooled to promote the 3D network formation. On the other hand, heat-set bigels (HSB) were produced by heating the emulsion (80 °C, 60 min). Bigels were evaluated through microscopy, FTIR, thermal and texture analyzes. Results showed that depending on the hydrogel:oleogel ratio and gelling mechanism different structures organization were obtained. CSB were more organized, showing that the rate of gelation was the mechanism responsible for the structure. However, for HSB the heat treatment destabilized the emulsion and disorganized structures were observed for high oleogel content. FTIR corroborates the visual observation and showed that the arrangement was purely physical. In addition, the structural arrangement led to different mechanical properties. In general, HSB produced gels with rubber-like behavior, higher elasticity modulus and the presence of a breaking point. In contrast, CSB behaves as squeezing gel, with no breaking point and lower values of elasticity modulus. Moreover, for O/W bigels the dispersed oleogel particles disrupted the WPI network decreasing the gel strength in comparison to pure hydrogels. However, for systems where oleogel was the continuous phase, the gel strength was recovered due to the metastable and dynamic character of these systems. Thus, results showed that the gelling mechanism of the protein exerted an effect on the physical properties of bigels. In addition, the mechanical properties also can be modulated according to the bigel composition, allowing its application in products with different sensorial characteristics.

Development of alkaline-stable nanoformulation of nisin: special insights through cytotoxic and antibacterial studies

Nisin, a thermostable, approved food preservative, has limited therapeutic applications because of its high pH and proteolytic enzyme instability. The unavailability of a rapid, simple method of detection also restricts the research of nisin. The objective of this study was to adapt the simple, rapid protein estimation method of detection for nisin formulation and to formulate and evaluate site-specific nanoformulation for therapeutic applications, viz. colon cancer, and anti-bacterial action. Three nanoformulations of nisin with chitosan, gellan gum, and dextran (ECN, EGN, and EDN) were prepared and characterized in vitro. Among three, EGN was selected as a good formulation based on its size surface charge, morphology, drug loading, and release characteristics. FT-IR and DSC revealed the interaction pattern and stability nature. The stability of nisin in an alkaline environment was confirmed by CD. Its therapeutic applications were proved by efficiency against colon cancer cells evaluated by MTT assay and AO/EB staining using Caco-2 cell lines. The in situ sol-gel mechanism imparted by gellan gum was proved the sole reason for the stability and activity of nisin in EGN at lower GIT. This was confirmed (using rheometer) by shear-thickening characteristics of formulation EGN in simulated colon fluid. The antibacterial activity against Staphylococcus aureus by disk diffusion method was also performed to confirm the retention of antimicrobial activity of nisin in EGN. Hence, gellan gum-nisin colloidal nanoparticles are found good candidates for drug delivery at lower GIT and stabilizing alkaline food materials.

Structural and Physicochemical Properties of Starch from Rejected Chestnut: Hydrothermal and High-Pressure Processing Dependence

The quality standards for the export of chestnuts generate large quantities of rejected fruits, which require novel processing technologies for their safe industrial utilization. This study aimed to investigate the impact of high-pressure processing (HPP) and hydrothermal treatments (HT) on the physicochemical properties of rejected chestnut starch. Chestnuts were treated by HPP at 400, 500, and 600 MPa for 5 min and HT at 50 °C for 45 min. In general, all HPP treatments did not induce starch gelatinization, and their granules preserved the integrity and Maltese-cross. Moreover, starch granules' size and resistant starch content increased with the intensity of pressure. Native and HT chestnut starches were the most susceptible to digestion. HPP treatments did not affect the C-type crystalline pattern of native starch, but the crystalline region was gradually modified to become amorphous. HPP-600 MPa treated starch showed modified pasting properties and exhibited the highest values of peak viscosity. This study demonstrates for the first time that after HPP-600 MPa treatment, a novel chestnut starch gel structure is obtained. Moreover, HPP treatments could increase the slow-digesting starch, which benefits the development of healthier products. HPP can be considered an interesting technology to obtain added-value starch from rejected chestnut fruits.

Gellan gum conjugation with soy protein via Maillard-driven molecular interactions and subsequent clustering lead to conjugates with tuned technological functionality

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Soy protein isolate (SPI) was conjugated to low acyl gellan gum (LAGG).

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Conjugate formation was confirmed by glycation degree (DG) and structural changes.

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SPI-LAGG conjugates were classified into low, medium, and high DG clusters.

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A low DG was enough to enhance the techno-functional properties of SPI.

Soy proteins are frequently used in the food industry; however, they have rigid and compact structure with relatively poor interfacial properties and solubility. This study was therefore aimed to modify techno-functional characteristics of soy protein isolate (SPI; 0.1% w/v) by conjugating to low acyl gellan gum (LAGG; 0.1, 0.2, and 0.3% w/v), through the Maillard reaction (at 90 °C for 90 min). The SPI-LAGG conjugates were confirmed by changes in pH, glycation degree (DG; up to 48%), Fourier transform infrared spectroscopy, and sodium dodecyl sulphate polyacrylamide electrophoresis. The conjugates were then classified into three clusters of low, medium, and high DG, via K-means clustering method. The low DG conjugate had lower surface hydrophobicity and foaming capacity, and higher thermal stability, solubility, emulsifying properties, foam stability, and antioxidant activity compared to the other clusters. This indicated that a low DG is required to enhance the functional properties of proteins.

Synthesis, characterization and application of antibacterial lactoferrin nanoparticles

Lactoferrin (L) and gellan gum (G) nanoparticles were produced in different biopolymer proportions through electrostatic complexation to enhance the antimicrobial properties of lactoferrin. The nanoparticles were characterized according to size, charge density, morphology and antimicrobial activity against S. aureus and E. coli, in two different broths to show the effect of the broth composition on the nanoparticle activity. The 9L:1G particles showed the highest positive zeta potential (+21.20 mV) and reduced diameter (92.03 nm) which resulted in a minimum inhibitory concentration six times smaller (0.3 mg/ml) than pure lactoferrin (2 mg/ml). However, the bacteriostatic action of nanoparticles was inhibited in the presence of divalent cations. When applied to strawberries as a coating, lactoferrin nanoparticles extended fruit shelf-life up to 6 days in the presence of carboxymethylcellulose (CMC). Therefore, lactoferrin-gellan gum complexation was proved to be a promising tool to enhance lactoferrin antimicrobial action and broaden its application as a food preserver.

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Positive charged nanoparticles showed 6 times lower MIC than pure lactoferrin.

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Bacteriostatic action of nanoparticles was inhibited in high salt environments.

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Nanoparticle allied to CMC coating extended the shelf life of strawberries.

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The growth of mesophilic bacteria in strawberries was retarded by nanoparticles.

A pH-sensitive curcumin loaded microemulsion-filled alginate and porous starch composite gels: Characterization, in vitro release kinetics and biological activity

To improve the controlled release and stability of the loaded drug, the alginate-porous starch solution, as the gel matrix (GM), was prepared and added into curcumin-loaded microemulsion (CUR-ME) in a certain proportion, and then mixed with slow-gelling agents (CaCO₃ + d-glucono-δ-lactone) to prepared curcumin-loaded microemulsion gel (CUR-ME-G). With increasing the proportion of GM from 25% (CUR-ME₃G₁) to 83% (CUR-ME₁G₅), the drug loading efficiency increased from 24% to 98% and the maximum drug loading capacity (14.9 mg/g) was found in CUR-ME₁G₃ with 75% GM. Moreover, a denser structure that entrapped all microemulsion droplets was formed with increasing the proportion of microemulsion according to the observation of scanning electron microscopy. This was also confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy that no new peaks appeared in CUR-ME-G, while the hydrogen bonding interactions might exist between curcumin and sodium alginate. The in vitro release of the CUR-ME-G followed diffusion-controlled mechanism that was consistent with the first-order kinetic model. The release rate depended on the components of the CUR-ME-G and the pH value of the release medium. CUR-ME-G with curcumin concentration of 0.20% exhibited the best biological activity. CUR-ME-G might provide a potential application in the smart drug delivery systems.

Exploiting the robust network structure of zein/low-acyl gellan gum nanocomplexes to create Pickering emulsion gels with favorable properties

Zein/low-acyl gellan gum (GG) composite particles (ZGPs) were fabricated to stabilize Pickering emulsions (termed "ZGPEs"). The wettability of ZGPs was manipulated simply by adjusting the concentration of GG. The effects of GG concentration, oil fraction and pH on ZGPEs were systematically evaluated by confocal laser scanning microscopy (CLSM), cryo-scanning electron microscopy (cryo-SEM), dynamic light scattering technique, stimulated emission depletion (STED) nanoscopy and rheology. The results showed that ZGPEs exhibited robust colloidal properties and distinct advantage over other previously reported zein-polysaccharide-based Pickering emulsions. CLSM, STED and cryo-SEM analyses revealed that the network structures formed by GG and ZGPs at the continuous phase and oil-water interface were the main contributors to the emulsion's characteristics. This study provides insights into the fabrication of food-grade Pickering emulsions with distinct characteristics that impart favorable properties to various foods and bioactive delivery systems.