Gelation of native beta-lactoglobulin induced by electrostatic attractive interaction with xanthan gum

Gels of carrageenan-caprine whey protein concentrate: A physicochemical study

Mixed gels of carrageenan (Car) and caprine whey protein concentrate (WPCc) (pH 7) were studied and compared with those prepared with Car and commercial bovine whey protein concentrate (WPCb). Dynamic rheology studies indicate that gels with WPCc were weaker (lower G') than those made with WPCb. However, textural parameters such as, hardness, springiness and cohesiveness were similar in both type of gels. The addition of CaCl2 incremented the elastic modulus (G'), hardness and adhesiveness of gels. The samples with caprine whey showed higher water holding capacity than samples with bovine whey. Confocal laser scanning microscope images of the gels, showed very different aspects according to the type of WPC used: WPCc-Car gels exhibited aggregates of proteins that interrupt the carrageenan network, while WPCb-Car gels showed a homogeneous appearance with proteins distributed throughout all the matrix.

Effect of Protein–Protein Interactions on Translational Diffusion of Spheroidal Proteins

One of the commonly accepted approaches to estimate protein–protein interactions (PPI) in aqueous solutions is the analysis of their translational diffusion. The present review article observes a phenomenological approach to analyze PPI effects via concentration dependencies of self- and collective translational diffusion coefficient for several spheroidal proteins derived from the pulsed field gradient NMR (PFG NMR) and dynamic light scattering (DLS), respectively. These proteins are rigid globular α-chymotrypsin (ChTr) and human serum albumin (HSA), and partly disordered α-casein (α-CN) and β-lactoglobulin (β-Lg). The PPI analysis enabled us to reveal the dominance of intermolecular repulsion at low ionic strength of solution (0.003–0.01 M) for all studied proteins. The increase in the ionic strength to 0.1–1.0 M leads to the screening of protein charges, resulting in the decrease of the protein electrostatic potential. The increase of the van der Waals potential for ChTr and α-CN characterizes their propensity towards unstable weak attractive interactions. The decrease of van der Waals interactions for β-Lg is probably associated with the formation of stable oligomers by this protein. The PPI, estimated with the help of interaction potential and idealized spherical molecular geometry, are in good agreement with experimental data.

Improving the Mechanical Properties of Red Clay Using Xanthan Gum Biopolymer

The traditional treatment of red clay using inorganic materials leads to many serious environmental problems. The study investigates the mechanical properties of red clay using an environmental-friendly material—xanthan gum—through confined compression, direct shear, and scanning electron microscope tests. At the macroscale, xanthan gum content and curing age had obvious effects on the compressibility, presenting the treated red clay was in the category of low compressibility which gradually increased when xanthan gum content exceeded 1.5%. The xanthan gum content and curing age also had significant influences on the cohesion but not on the internal friction angle. The shear strength of red clay can be improved by increasing the cohesion without obviously changing the friction characteristics. After curing for 28 days, the cohesion and internal friction angle of 2.0% xanthan gum-treated soil were effectively improved to 170.44 kPa and 20.56°, which were increased by 69.79% and 9.36°, respectively, compared with untreated red clay. Microscopic analysis indicated that the strengthening mechanism by xanthan gum was derived from changing the arrangement characteristics of soil particles and forming hard biopolymer-red clay matrices. The proper xanthan gum can effectively wrap clay particles and fill pore spaces. However, the extensive stacking of gels would also reduce the effective connection of clay particles and produce local weak points in the soil, resulting in attenuation of mechanical properties. This study enriches the treatment measure of red clay and provides beneficial experiences for biopolymer application on special clay.

Effects of Salts on Structural, Physicochemical and Rheological Properties of Low-Methoxyl Pectin/Sodium Caseinate Complex

The addition of salts is an effective way to improve the properties of polysaccharide/protein complexes for use in foods. However, there is no comparative study on the effects of different ions on the complex system of low methoxyl pectin (LMP)/ sodium caseinate (CAS) complex. The effects of different concentrations of three salt ions (Na⁺, K⁺, Ca²⁺) on the physicochemical and rheological properties of the LMP/CAS complex were determined in this study, and the structure of LMP/CAS complex was characterized. The results showed that the addition of these three salt ions affected zeta potential, particle size, and turbidity of the LMP/CAS complex, and lead the LMP/CAS complex to form a more regular and uniform network structure, which helped improve its stability, solubility, and rheological properties. The particle size and turbidity value of the complex achieved with Ca²⁺ were higher than those obtained using Na⁺ and K⁺. Moreover, the secondary structure of the proteins in the complex changed to adding high concentrations of Ca²⁺. Our study provides valuable information for the application of the LMP/CAS complex in the food industry.

Newer guar gum ester/chicken feather keratin interact films for tissue engineering

This work intends to synthesis newer guar gum indole acetate ester and design film scaffolds based on protein-polysaccharide interactions for tissue engineering applications. Guar gum indole acetate(GGIA) was synthesized for the first time from guar gum in presence of aprotic solvent activated hofmeister ions. The newer biopolymer was fully characterized in FT-IR,¹³C NMR, XRD and TGA analysis. High DS (Degree of Substitution, DS = 0.61) GGIA was cross-linked with hydrolyzed keratin, extracted from chicken feather wastes. Films were synthesized from different biopolymer ratios and the surface chemistry appeared interesting. Physicochemical properties for GGIA-keratin association were notable. Fully bio-based films were non-cytotoxic and exhibited excellent biocompatibility for human dermal fibroblast cell cultivations. The film scaffold showed 63% porosity and the recorded tensile strength at break was 6.4 MPa. Furthermore, the standardised film exerted superior antimicrobial activity against both the Gram-positive and Gram-negative bacteria. MICs were recorded at 130 μg/mL and 212 μg/mL for E. coli and S. aureus respectively. In summary, GGIA-keratin film scaffolds represented promising platforms for skin tissue engineering applications.

Physicochemical characterization of protein isolates of amaranth and common bean and a study of their compatibility with xanthan gum

Vegetables are considered to be a sustainable source of promising biomaterials such as proteins and polysaccharides. In this study, four protein isolates (amaranth protein isolate API, amaranth globulin-rich protein isolate AGR, bean protein isolate BPI, and bean phaseolin-rich protein isolate BPR) were structurally characterized under different pH conditions (2-12) and their compatibility behavior with xanthan gum (XG) in aqueous medium was described. All protein isolates showed β turn and β sheet (78.24-81.11%), as the major secondary structures without statistically significant difference under the pH conditions surveyed. Protein isolates show solubility at pH ≤ 3 (40.4-85.1%) and pH ≥ 8 (57.6-99.9%) and surface hydrophobicity results suggest protein denaturation at pH ≤ 3. In the compatibility study, API/XG ratios between 1:1 and 5:1 at pH from 7 to 9 and the BPI/XG ratios from 1:1 to 20:1 at pH 7 form gels that do not require heating nor crosslinking agent addition. Zeta potential results, on the other hand, evidenced that formation of gels is driven by attractive electrostatic interaction of the charged regions of both biopolymers and intermolecular interactions such as hydrogen bonds.

Addition of Anionic Polysaccharide Stabilizers Modulates In Vitro Digestive Proteolysis of a Chocolate Milk Drink in Adults and Children

There is a need to better understand the possible anti-nutritional effect of food stabilizers on the digestibility of important macronutrients, like proteins. This study hypothesized that the anionic nature of κ-, ι-, λ-, Carrageenan (CGN) and xanthan gum directs their interactions with food proteins leading to their subsequent attenuated digestive proteolysis. Model chocolate milk drinks were tested for their colloidal properties, viscosity and proteolytic breakdown in adults and children using in vitro digestion models coupled with proteomic analyses. SDS-PAGE analyses of gastro-intestinal effluents highlight stabilizers hinder protein breakdown in adults and children. Zeta potential and colloidal particle size were the strongest determinants of stabilizers’ ability to hinder proteolysis. LC-MS proteomic analyses revealed stabilizer addition significantly reduced bioaccessibility of milk-derived bioactive peptides with differences in liberated peptide sequences arising mainly from their location on the outer rim of the protein structures. Further, liberation of bioactive peptides emptying from a child stomach into the intestine were most affected by the presence of ι-CGN. Overall, this study raises the notion that stabilizer charge and other properties of edible proteins are detrimental to the ability of humans to utilize the nutritional potential of such formulations. This could help food professionals and regulatory agencies carefully consider the use of anionic stabilizers in products aiming to serve as protein sources for children and other liable populations.

Hydrogels assembled from ovotransferrin fibrils and xanthan gum as dihydromyricetin delivery vehicles

Novel ovotransferrin fibril–xanthan gum hydrogels were assembled to deliver dihydromyricetin effectively.

Rapid cultivation of aerobic granular sludge by xanthan gum in SBR reactors

This study focuses on the effect of xanthan gum on aerobic sludge granulation, through close monitoring of the physical and chemical changes of the aerobic granular sludge, and treatment performance. Two sequencing batch reactors (SBRs), R1 and R2, were seeded with activated sludge only (R1) and with a mixture of activated sludge and 40 mg/L of xanthan gum (R2). The results showed that granulation finished on the 20th day in R2, far faster than the granulation time of 30 days in R1. Meanwhile, there was a reliably higher sludge concentration, better settling properties and better particle mechanical strength in R2, and better removal performance of total nitrogen (TN) and chemical oxygen demand (COD). The results demonstrated that seeding xanthan gum enhanced the aerobic sludge granulation in the SBR. Maybe its anionic and hydrophilic surface characteristics facilitate interactions with cations and other polysaccharides, inducing stronger gelation, which promoted the formation of particles or increased the internal relationship between particles, thereby increasing the cohesion within the sludge, so that the granular sludge was not easily broken.

Encapsulation of active ingredients in polysaccharide-protein complex coacervates

Polysaccharide-protein complex coacervates are amongst the leading pair of biopolymer systems that has been used over the past decades for encapsulation of numerous active ingredients. Complex coacervation of polysaccharides and proteins has received increasing research interest for the practical application in encapsulation industry since the pioneering work of complex coacervation by Bungenburg de Jong and co-workers on the system of gelatin-acacia, a protein-polysaccharide system. Because of the versatility and numerous potential applications of these systems essentially in the fields of food, pharmaceutical, cosmetics and agriculture, there has been intense interest in recent years for both fundamental and applied studies. Precisely, the designing of the micronscale and nanoscale capsules for encapsulation and control over their properties for practical applications garners renewed interest. This review discusses on the overview of polysaccharide-protein complex coacervates and their use for the encapsulation of diverse active ingredients, designing and controlling of the capsules for delivery systems and developments in the area.

Formation and functional properties of protein-polysaccharide electrostatic hydrogels in comparison to protein or polysaccharide hydrogels

Protein and polysaccharide mixed systems have been actively studied for at least 50years as they can be assembled into functional particles or gels. This article reviews the properties of electrostatic gels, a recently discovered particular case of associative protein-polysaccharide mixtures formed through associative electrostatic interaction under appropriate solution conditions (coupled gel). This review highlights the factors influencing gel formation such as protein-polysaccharide ratio, biopolymer structural characteristics, final pH, ionic strength and total solid concentration. For the first time, the functional properties of protein-polysaccharide coupled gels are presented and discussed in relationship to individual protein and polysaccharide hydrogels. One of their outstanding characteristics is their gel water retention. Up to 600g of water per g of biopolymer may be retained in the electrostatic gel network compared to a protein gel (3-9g of water per g of protein). Potential applications of the gels are proposed to enable the food and non-food industries to develop new functional products with desirable attributes or new interesting materials to incorporate bioactive molecules.

Protein/polysaccharide complexes and coacervates in food systems

Since the pioneering work of Bungenberg de Jong and co-workers on gelatin-acacia gum complex coacervation in the 1920-40s, protein/polysaccharide complexes and coacervates have received increasing research interest in order to broaden the possible food applications. This review focuses on the main research streams followed in this field during the last 12 years regarding: i) the parameters influencing the formation of complexes and coacervates in protein-polysaccharide systems; ii) the characterization of the kinetics of phase separation and multi-scale structure of the complexes and coacervates; and iii) the investigation of the functional properties of complexes and coacervates in food applications. This latter section encompasses various technological aspects, namely: the viscosifying and gelling ability, the foaming and emulsifying ability and finally, the stabilization and release of bioactives or sensitive compounds.