Free Amino Groups Research Articles

Type of pectin affects the functionality of potato protein-pectin conjugates in emulsions

This study investigated the effect of the molecular structure of pectin on conjugate formation and its functionality in plant protein-based emulsions. For this purpose, high-methoxylated, low-methoxylated, amidated citrus pectin and their mixtures with potato protein were vacuum-dried at defined process conditions. The change in free amino groups, colour and molecular weight distribution assessed conjugation. The side reaction, such as pectin degradation, was monitored by the degree of methoxylation, galacturonic acid content and intrinsic viscosity. In addition, FT-IR and hydrophobicity measurements were performed to determine the changes in chemical structure due to the occurring reactions. The ζ-potential, solubility and oil droplet size reflected the functionality of the conjugated samples.The results confirm that, apart from the conjugation of protein and pectin, where the most significant decrease in free amino groups was obtained with an increasing degree of methoxylation or presence of amide groups, undesirable degradation of pectin occurring, resulting in a broad molecular weight distribution of the conjugate samples. The conjugate formation was the highest with amidated pectin. The FT-IR measurements confirmed the formation of Maillard conjugates. The FT-IR spectra showed a decrease in the intensity signals of amide I and amide II and the formation of new C–N bond maxima. In addition, the conjugation caused the shift of the protein's isoelectric point to the acidic environment, resulting in higher solubility and improved emulsion stability at the isoelectric point of the protein.Regarding emulsion stability, the conjugates with amidated pectin performed best and achieved the narrowest oil droplet size distribution over a wider pH range. Emulsion-stabilising properties of conjugates with high- and low-methoxylated pectin differed only slightly. To better understand the underlying mechanisms for emulsion stabilisation, future research will focus on the interfacial properties of the conjugates as determined by interfacial shear rheology and pendant drop analysis.

Synthesis of linear polyesters bearing amino groups via lipase-catalyzed polymerization of N-protected monomer and deprotection

Linear biodegradable polyesters with a controlled number of side chains of amino groups have been synthesized. Such polyesters with a large number of amino side groups can be conjugated with a wide variety of functional molecules to obtain multi-functional biodegradable polyesters. In this study, poly(1,3-propylene-co-2-amino-1,3-propylene) adipate) (P(P-co-AP)A) was synthesized by enzymatic polymerization of divinyl adipate, 1,3-propanediol, and N-Boc-2-amino-1,3-propanediol (BocAPDO), and subsequent deprotection under strong acidic conditions. The mild reaction conditions and the specificity of the enzymatic polymerization could effectively inhibit side reactions, while the protecting groups of the monomers prevented polymer branching from the amino groups. It was found that the introduction rates of BocAPDO in the polymers could be well-controlled as the feeding rates changed from 0 to 100 mol%. After the deprotection and desalting, the ester groups in the main chain gradually converted into amide groups by intramolecular ester aminolysis at room temperature for a few days due to nucleophilic free amino groups. It was also found that the synthesized functional copolymers were all amorphous, since the random component of amino groups disrupted the crystallinity of poly(1,3-propylene adipate) (PPA). The glass transition temperature gradually increased with the increase in the content of 2-amino-1,3-propylene adipate (APA), eventually reaching −0.4 °C at the APA content of 100 mol% due to the intermolecular hydrogen bonding. Moreover, P(P-co-AP)A shows high hygroscopicity, where 3.9 wt% and 8.1 wt% of water were absorbed in the polymers with the APA contents of 50 and 100 mol%, respectively, when left in air at 60–70 % humidity for 6 h. Thus, the hydrophilicity dramatically improved with the increase in the APA content, eventually resulting in the acquisition of water solubility. The model post-polymerization modification using butyric acid was also conducted, and it was confirmed that carboxylic acids could be conjugated to the polymers by simple condensation reaction. Since polymerization of functional monomers is generally susceptible to the polarity of metal catalysts, the mild and selective reaction employed in this study could realize a higher content of various functional groups in the side chains of polyesters leading to a newly designed multi-functional polyester.

Effects of purple cabbage anthocyanin extract on the gluten characteristics and the gluten network evolution of high-gluten dough.

Anthocyanins are polyphenolic pigments that have hypoglycemic, antioxidation, anti-aging, and other effects. Research has shown that polyphenols can optimize the processing of dough and improve the texture and nutritional characteristics of dough products. The formation of gluten networks is decisive for the quality of flour products. The effects of purple cabbage anthocyanin (PCA) extract on the structure, microscopic morphology, and network formation of gluten protein were studied, and the types of cross-linking between PCA and gluten protein are discussed. The results show that PCA extract increased the free sulfhydryl (SH) group content and the free amino group of gluten proteins, stimulated an increase in the β-sheet ratio and the decrease of α-helix ratio, and increased the gluten index significantly (P < 0.05). The PCA extract also induced gluten protein aggregation, increased the height of protein molecular chains, and stimulated the formation of gluten networks. When PCA extract concentrations were 4 g kg-1 and 8 g kg-1, the gluten network was more homogeneous, continuous, and dense. Appropriate anthocyanins have a positive effect on the properties of gluten and promote the formation of gluten networks. Excessive anthocyanins destroy gluten protein interaction and harm gluten cross-linking. This study may provide a useful source of data for the production of functional flour products rich in anthocyanins. © 2024 Society of Chemical Industry.

Effects of polyphenols from walnut pellicle on the structure and allergenicity of walnut globulin

This study investigated the effects of polyphenols from walnut pellicle on the structure and allergenicity of walnut globulin (WG). The allergenicity-guided assay revealed walnut globulin (WG) from walnut defatted powder without pellicle was the most allergenic protein fraction of walnut. Complexes of phenolic extracts from walnut pellicle (PEWP) and WG were prepared in different ratio and pH conditions to further investigate the effect of PEWP on the protein structure and allergenicity of globulin. The covalent interaction between PEWP and WG in pH 7 was lower than pH 11, according to the free amino groups' content and SDS-PAGE analysis. Comprehensive methods characterized the complexes, including UV–Visible, fluorescence, Fourier transform infrared, and circular dichroism spectroscopy, and indicated that combination of polyphenols with protein altered the secondary and tertiary structure of the protein, leading to the unfolding of the protein structure. Meanwhile, the combination with PEWP reduced the IgG-binding capacity of WG in a dose-dependent manner, reaching a minimum of 26.90 ± 4.31% (at pH 7), which was significantly (P < 0.05) lower compared to that at pH 11 (41.79 ± 1.25%). Correlation analysis revealed a significant correlation between IgG-binding capacity and protein structure, as well as the addition concentration of PEWP (r = −0.85, P < 0.01), and pH conditions may indirectly influence the structure and allergenicity of the protein by affecting the interaction between WG and PEWP. The interaction between WG and PEWP was characterized through fluorescence-quenching mechanism analysis, indicating that polyphenols from PEWP mainly interact with WG through hydrogen bond and hydrophobic interaction.

Improvement in the Sustained-Release Performance of Electrospun Zein Nanofibers via Crosslinking Using Glutaraldehyde Vapors.

Volatile active ingredients in biopolymer nanofibers are prone to burst and uncontrolled release. In this study, we used electrospinning and crosslinking to design a new sustained-release active packaging containing zein and eugenol (EU). Vapor-phase glutaraldehyde (GTA) was used as the crosslinker. Characterization of the crosslinked zein nanofibers was conducted via scanning electron microscopy (SEM), mechanical properties, water resistance, and Fourier transform infrared (FT-IR) spectroscopy. It was observed that crosslinked zein nanofibers did not lose their fiber shape, but the diameter of the fibers increased. By increasing the crosslink time, the mechanical properties and water resistance of the crosslinked zein nanofibers were greatly improved. The FT-IR results demonstrated the formation of chemical bonds between free amino groups in zein molecules and aldehyde groups in GTA molecules. EU was added to the zein nanofibers, and the corresponding release behavior in PBS was investigated using the dialysis membrane method. With an increase in crosslink time, the release rate of EU from crosslinked zein nanofibers decreased. This study demonstrates the potential of crosslinking by GTA vapors on the controlled release of the zein encapsulation structure containing EU. Such sustainable-release nanofibers have promising potential for the design of fortified foods or as active and smart food packaging.

Human In Vitro Oxidized Low-Density Lipoprotein (oxLDL) Increases Urinary Albumin Excretion in Rats.

Hypercholesterolemia-associated oxidative stress increases the formation of oxidized low-density lipoprotein (oxLDL), which can affect endothelial cell function and potentially contribute to renal dysfunction, as reflected by changes in urinary protein excretion. This study aimed to investigate the impact of exogenous oxLDL on urinary excretion of albumin and nephrin. LDL was isolated from a patient with familial hypercholesterolemia (FH) undergoing lipoprotein apheresis (LA) and was oxidized in vitro with Cu (II) ions. Biochemical markers of LDL oxidation, such as TBARS, conjugated dienes, and free ε-amino groups, were measured. Wistar rats were treated with a single intraperitoneal injection of PBS, LDL, or oxLDL (4 mg of protein/kg b.w.). Urine was collected one day before and two days after the injection. We measured blood lipid profiles, urinary protein excretion (specifically albumin and nephrin), and markers of systemic oxidative stress (8-OHdG and 8-iso-PGF2α). The results showed that injection of oxLDL increased urinary albumin excretion by approximately 28% (310 ± 27 μg/24 h vs. 396 ± 26 μg/24 h, p = 0.0003) but had no effect on nephrin excretion. Neither PBS nor LDL had any effect on urinary albumin or nephrin excretion. Additionally, oxLDL did not affect systemic oxidative stress. In conclusion, hypercholesterolemia may adversely affect renal function through oxidatively modified LDL, which interferes with the renal handling of albumin and leads to the development of albuminuria.

Antibody-Drug Conjugate Made of Zoledronic Acid and the Anti-CD30 Brentuximab-Vedotin Exert Anti-Lymphoma and Immunostimulating Effects.

Relevant advances have been made in the management of relapsed/refractory (r/r) Hodgkin Lymphomas (HL) with the use of the anti-CD30 antibody-drug conjugate (ADC) brentuximab-vedotin (Bre-Ved). Unfortunately, most patients eventually progress despite the excellent response rates and tolerability. In this report, we describe an ADC composed of the aminobisphosphonate zoledronic acid (ZA) conjugated to Bre-Ved by binding the free amino groups of this antibody with the phosphoric group of ZA. Liquid chromatography-mass spectrometry, inductively coupled plasma-mass spectrometry, and matrix-assisted laser desorption ionization-mass spectrometry analyses confirmed the covalent linkage between the antibody and ZA. The novel ADC has been tested for its reactivity with the HL/CD30+ lymphoblastoid cell lines (KMH2, L428, L540, HS445, and RPMI6666), showing a better titration than native Bre-Ved. Once the HL-cells are entered, the ADC co-localizes with the lysosomal LAMP1 in the intracellular vesicles. Also, this ADC exerted a stronger anti-proliferative and pro-apoptotic (about one log fold) effect on HL-cell proliferation compared to the native antibody Bre-Ved. Eventually, Bre-Ved-ZA ADC, in contrast with the native antibody, can trigger the proliferation and activation of cytolytic activity of effector-memory Vδ2 T-lymphocytes against HL-cell lines. These findings may support the potential use of this ADC in the management of r/r HL.

Green preparation of Fe3O4/HA/CS magnetic nanoparticles for oil–water separation

AbstractBACKGROUNDDemulsification using chitosan (CS)‐coated magnetic nanomaterials has garnered significant attention. However, traditional methods for synthesizing chitosan (CS)‐coated magnetic nanomaterials are often contaminated, laborious, and time‐consuming. Moreover, they showed poor demulsification efficiency due to the occupation of free amino groups in CS by crosslinking agents.RESULTSCS‐coated Fe3O4 magnetic nanoparticles (MNPs) were synthesized using humic acid (HA) as a bridge. The Fe3O4/HA/CS MNPs are recyclable demulsifiers for hexadecane‐water microemulsions. The impacts of MNP dosage, separation time, and pH on demulsification efficiency were studied comprehensively. Compared with Fe3O4/HA and Fe3O4/CS MNPs, the demulsification efficiency of the Fe3O4/HA/CS MNPs was superior. The pseudo‐second‐order kinetic model and the Sips isotherm best describe the demulsification process. Combined with the influence factors of demulsification efficiency, the demulsification mechanism involves electrostatic interactions between MNPs and oil microparticles. The maximum adsorption capacity for oil by the Fe3O4/HA/CS MNPs was 91.73 mg g−1.CONCLUSIONThis research presents a new method for connecting CS to MNPs with a high surface positive charge. As synthesized Fe3O4/HA/CS MNPs is expected to serve as highly efficient and recyclable demulsifiers for emulsified oil wastewater. © 2024 Society of Chemical Industry (SCI).

Synthesis of Thermoresponsive Chitosan-graft-Poly(N-isopropylacrylamide) Hybrid Copolymer and Its Complexation with DNA.

A hybrid synthetic-natural, thermoresponsive graft copolymer composed of poly(N-isopropyl acrylamide) (PNIPAM) side chains, prepared via RAFT polymerization, and a chitosan (Chit) polysaccharide backbone, was synthesized via radical addition-fragmentation reactions using the "grafting to" technique, in aqueous solution. ATR-FTIR, TGA, polyelectrolyte titrations and 1H NMR spectroscopy were employed in order to validate the Chit-g-PNIPAM copolymer chemical structure. Additionally, 1H NMR spectra and back conductometric titration were utilized to quantify the content of grafted PNIPAM side chains. The resulting graft copolymer contains dual functionality, namely both pH responsive free amino groups, with electrostatic complexation/coordination properties, and thermoresponsive PNIPAM side chains. Particle size measurements via dynamic light scattering (DLS) were used to study the thermoresponsive behavior of the Chit-g-PNIPAM copolymer. Thermal properties examined by TGA showed that, by the grafting modification with PNIPAM, the Chit structure became more thermally stable. The lower critical solution temperature (LCST) of the copolymer solution was determined by DLS measurements at 25-45 °C. Furthermore, dynamic and electrophoretic light scattering measurements demonstrated that the Chit-g-PNIPAM thermoresponsive copolymer is suitable of binding DNA molecules and forms nanosized polyplexes at different amino to phosphate groups ratios, with potential application as gene delivery systems.

Heat Treatment and Homogenization Influence the Gastric Digestion of Bovine Milk Protein in Growing Pigs as an Adult Human Model

BackgroundBovine milk processing influences the structure of the curd formed during gastric digestion, which may alter gastric protein hydrolysis and impact amino acid (AA) release into the small intestine. ObjectivesThis study aimed to determine the influence of heat treatment and homogenization on the gastric protein digestion and AA emptying of bovine milk. MethodsNine-wk-old pigs (n = 144) consumed either raw, pasteurized nonhomogenized (PNH), pasteurized homogenized (PH), or ultra-high-temperature homogenized (UHT) bovine milk for 10 d. On day 11, fasted pigs received the milk treatment (500 mL) before gastric contents were collected at 0, 20, 60, 120, 180, and 300 min postprandially. The apparent degree of gastric protein hydrolysis (based on the release of free amino groups), apparent gastric disappearance of individual proteins [based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel band intensity], and the gastric emptying of digested protein and AA were determined. ResultsDuring the first 60 min, the rate of apparent gastric protein hydrolysis was fastest in pigs fed UHT milk (0.29%/min compared with on average 0.07%/min in pigs fed raw, PNH, and PH milk). Differences in the apparent degree of gastric protein hydrolysis and emptying were reflected in the rate of digested protein entering the small intestine. The AA gastric emptying half-time was generally shorter in pigs fed PH and UHT milk than in pigs fed raw and PNH milk. For example, the gastric release of total essential AA was >2-fold faster (P < 0.01) in pigs fed PH or UHT milk than that in pigs fed raw or PNH milk (i.e., homogenized compared with nonhomogenized milk). ConclusionsHeat treatment and homogenization increased the apparent gastric degree of protein hydrolysis and the release of digested protein into the small intestine. However, the rate of AA entering the small intestine was mainly increased by homogenization.

Endophthalmitis therapy revolution: Proof of concept based on in vivo evaluation of maleic acid modified chitosan

The aim was to develop chitosan-maleic acid (CS-MA) based ocular inserts with enhanced mucoadhesiveness for prevention of endophthalmitis caused by Escherichia coli. Therefore, chitosan (CS) and maleic acid (MA) were conjugated via formation of amide bond. Characterization via proton nuclear magnetic resonance and infrared spectroscopy was carried out and attached maleic acid groups were quantified by free amino groups assay. Biocompatibility of the conjugate was assessed following resazurin assay on fibroblasts, membrane damage on human erythrocytes and Hen's Egg-Chorioallantoic membrane tests. Inserts were pressed and characterized in terms of swelling behavior, pH, hardness, in vitro drug release and disintegration. To test mucoadhesive properties of CS-MA inserts, rheometer, rotating cylinder, inclined plane, and texture analyzer were the instruments utilized. Furthermore, antibacterial efficacy of the conjugate was established by direct agar diffusion method and in vivo Draize test was carried out to determine tolerability of the inserts. Results exhibited successful synthesis of the biomaterial, maintaining the great biocompatibility of native chitosan even though a 68.81 % of modification was achieved. Additionally, mucoadhesive studies showed improved properties of CS-MA compared to native polymer, with 2.42-fold, 4-fold, 3.42-fold and 4.05-fold increase in dynamic viscosity, retention time, overall attachment work and peak force of detachment, respectively. Finally, antibacterial activity was enhanced in 1.77-fold and in vivo experiments showed no irritation and good tolerability of CS-MA inserts. In conclusion, CS-MA ocular inserts effectively developed exhibiting promising features capable of revolutionizing the endophthalmitis therapy field.

Water-Insoluble, Thermostable, Crosslinked Gelatin Matrix for Soft Tissue Implant Development.

In this present study, the material science background of crosslinked gelatin (GEL) was investigated. The aim was to assess the optimal reaction parameters for the production of a water-insoluble crosslinked gelatin matrix suitable for heat sterilization. Matrices were subjected to enzymatic degradation assessments, and their ability to withstand heat sterilization was evaluated. The impact of different crosslinkers on matrix properties was analyzed. It was found that matrices crosslinked with butanediol diglycidyl ether (BDDE) and poly(ethylene glycol) diglycidyl ether (PEGDE) were resistant to enzymatic degradation and heat sterilization. Additionally, at 1 v/v % crosslinker concentration, the crosslinked weight was lower than the starting weight, suggesting simultaneous degradation and crosslinking. The crosslinked weight and swelling ratio were optimal in the case of the matrices that were crosslinked with 3% and 5% v/v BDDE and PEGDE. FTIR analysis confirmed crosslinking, and the reduction of free primary amino groups indicated effective crosslinking even at a 1% v/v crosslinker concentration. Moreover, stress-strain and compression characteristics of the 5% v/v BDDE crosslinked matrix were comparable to native gelatin. Based on material science measurements, the crosslinked matrices may be promising candidates for scaffold development, including properties such as resistance to enzymatic degradation and heat sterilization.

Modification of hordein by gallic acid in ethanol-free environments: Impact of covalent and non-covalent interactions on structure, physicochemical properties and self-assembly

The objectives of this study were to modify hordein with gallic acid (GA) in alcohol-free media and to compare the impact of covalent and non-covalent binding on the properties of hordein. Covalent hordein-GA complexes (H-GA) and non-covalent hordein/GA complexes (H/GA) were distinguished by molecular weight, free sulfhydryl groups and free amino groups. Isothermal titration calorimetry (ITC) demonstrated that physical mixing induced non-covalent binding of GA to hordein via hydrogen bonding and hydrophobic interactions, with a lower binding efficiency than covalent ones. Both complexation types led to a structural shift of hordein toward disorder, while grafting of oligomeric GA and alkaline treatment resulted in lower surface hydrophobicity and higher antioxidant activity of H-GA compared to H/GA. The nanoparticles assembled from H-GA had smaller particle sizes and higher physical stability than those formed from H/GA. The results of this study may provide new insights into the modification of hordein by polyphenols.

Water bridges as the trigger in an amino functionalized Zn-MOF for highly selective and sensitive fluorescent sensing of water

Water is a fundamental element for life. The highly selective and sensitive sensing of water is always attractive for mankind in activities such as physiological processes study and extraterrestrial life exploration. Fluorescent MOFs with precise channels and functional groups might specifically recognize water molecules with hydrogen-bond interaction or coordination effects and work as water sensors. As a proof of concept, herein, an amino functionalized Zn-MOF (named as complex 1) with pores that just right for water molecules to form hydrogen bond bridges is revealed for highly selective and sensitive fluorescent sensing of water. The single-crystal X-ray diffraction analysis indicates that the 3D framework of complex 1 is functionalized with free amino groups in the channels. Hydrogen bonds formed in the channel along b-axis as water bridges to connect two adjacent NH2bdc ligands and result in the restriction of intramolecular motions (RIM) which could responsible for the selective turn-on fluorescence response to water. Complex 1 exhibits high sensitive to trace amount of water in organic solvents and could be used for water detection in a wide range water contents. Take advantages of complex 1, portable sensors (complex 1@PMMA) were prepared and used in the highly sensitive water sensing.

Effects of three polyphenols with different numbers of phenolic hydroxyls on the structural and interfacial properties and lipid-protein co-oxidation of oil body emulsions

Oil bodies (OBs) are organelles for storing lipids, and they are composed of lipid cores and monolayer phospholipid protein membranes. During storage, membrane proteins anchored in the lipid core are often damaged by lipid oxidation products, leading to oxidative damage and a decreased quality of emulsified foods. Here, three natural antioxidants (gallic acid (GA), epigallocatechin gallate (EGCG), and tannic acid (TA)) were added to OB emulsions to study the effects of polyphenols on protein interfacial properties during oxidation and the lipid-protein co-oxidation behavior. Compared to GA, EGCG and TA with higher molecular weights and hydroxyl substitution showed better antioxidant activity, metal chelating activity, iron reduction ability, and affinity for OB. The polyphenols significantly reduced the contents of free amino and sulfhydryl groups in OB. Infrared spectroscopy analysis indicate that hydrogen bonding and hydrophobic interactions may exist between the polyphenols and OB. During storage, polyphenols inhibited >23% of the primary and secondary lipid oxidation products in the emulsions, whereas the formation of carbonyl groups and disappearance of sulfhydryl groups were only inhibited by 10.7% and 7.4%, respectively, indicating that polyphenols preferentially inhibited lipid oxidation over protein oxidation. Electrophoresis results showed that moderate oxidation (3 days of storage) disrupted the disulfide bonds of proteins. Note that moderate oxidation enhanced the interfacial properties of OB proteins, whereas excessive oxidation led to protein aggregation. This study offers new perspectives on using polyphenols to regulate the lipid-protein co-oxidation in OB, as well as the different properties of OB proteins after oxidation.

The effects of advanced glycation end-products on skin and potential anti-glycation strategies.

The advanced glycation end-products (AGEs) are produced through non-enzymatic glycation between reducing sugars and free amino groups, such as proteins, lipids or nucleic acids. AGEs can enter the body through daily dietary intake and can also be generated internally via normal metabolism and external stimuli. AGEs bind to cell surface receptors for AGEs, triggering oxidative stress and inflammation responses that lead to skin ageing and various diseases. Evidence shows that AGEs contribute to skin dysfunction and ageing. This review introduces the basic information, the sources, the metabolism and absorption of AGEs. We also summarise the detrimental mechanisms of AGEs to skin ageing and other chronic diseases. For the potential strategies for counteracting AGEs to skin and other organs, we summarised the pathways that could be utilised to resist glycation. Chemical and natural-derived anti-glycation approaches are overviewed. This work offers an understanding of AGEs to skin ageing and other chronic diseases and may provide perspectives for the development of anti-glycation strategies.

Formation of casein micelles from bovine caseins simulating human casein phosphorylation patterns: Micellar structure and in vitro infant gastrointestinal digestion

This study investigated the micellar structure and in vitro infant gastrointestinal digestion of formed casein micelles simulating human casein composition and phosphorylation patterns. Caseins were fractionated from bovine caseins and formulated according to human casein composition, i.e., β-, κ- and αs1-caseins with a ratio of 68:20:12. The formulated caseins were dephosphorylated for different times and were mixed to obtain mixed phosphorylation patterns (FC-MP) for β-casein, showing 0–5 phosphate groups comparable to human β-casein. The formulated caseins without dephosphorylation and with high dephosphorylation, showing 5 phosphate groups and 0–2 phosphate groups for β-casein, respectively, were categorized as high (FC-HP) and low phosphorylated (FC-LP). With the average mineral concentrations found in human milk, CaCl2, MgCl2, citrate and inorganic phosphate were added into the different formulated casein dispersions to obtain casein micelles (FM-HP, FM-MP and FM-LP). Compared to FM-HP, FM-MP was closer to human micelles in relation to particle size, micellar hydration, molar ratio of Ca:casein, morphology and internal structure, whereas FM-LP showed did not show a characteristic micellar structure and had a larger size and lower molar ratio of Ca:casein. For gastrointestinal digestion, FM-MP was closer to human micelles in terms of the gastric flocs, casein degradation rate, free amino groups, and molecular weight distribution of peptides compared to FM-HP, whereas FM-LP showed larger flocs and lower casein degradation rate. These results show the significance of post-translational phosphorylation in facilitating the assembly of caseins into micellar structures, indicating the potential to form human-like micelles for application in infant formulae.

Structure and digestibility of bovine casein complexes formed by enriching κ- and β-caseins in micellar casein concentrate together with minerals adjustment

Colloidal structure and infant in vitro gastrointestinal digestibility of casein complexes simulating caseins and minerals compositions of human casein micelles were studied. κ- and β-Caseins were fractionated from bovine micellar casein concentrate (MCC), and mixed with MCC to increase their ratios to 20% and 68%, followed by adding citrate (Cit), calcium (Ca), and inorganic phosphate (Pi) to obtain the casein complexes. The complexes enriched with κ- and β-caseins showed higher percentages of serum Ca, Pi and caseins, larger particle size, and looser internal structure. During gastric digestion, the complexes enriched with κ- and β-caseins formed smaller and looser coagula, which promoted degradation of intact caseins and formation of free amino groups and small peptides. During initial intestinal digestion, the complexes enriched with κ- and β-caseins formed more free amino groups and smaller peptides. These results offered a potential strategy to form human casein micelles analogues for use in infant formula.

Surface Treatment Effect on the Mechanical and Thermal Behavior of the Glass Fabric Reinforced Polysulfone.

The chemical structure of the surface of glass fibers, including silanized fibers, was studied. Highly efficient heat-resistant composites were obtained by impregnating silanized glass fiber with a polysulfone solution, and the effect of modification of the surface of glass fibers on the physical, mechanical and thermophysical properties of the composite materials was studied. As a result of the study, it was found that the fiber-to-polymer ratio of 70/30 wt.% showed the best mechanical properties for composites reinforced with pre-heat-treated and silanized glass fibers. It has been established that the chemical treatment of the glass fibers with silanes makes it possible to increase the mechanical properties by 1.5 times compared to composites reinforced with initial fibers. It was found that the use of silane coupling agents made it possible to increase the thermal stability of the composites. Mechanisms that improve the interfacial interaction between the glass fibers and the polymer matrix have been identified. It has been shown that an increase in adhesion occurs both due to the uniform distribution of the polymer on the surface of the glass fibers and due to the improved wettability of the fibers by the polymer. An interpenetrating network was formed in the interfacial region, providing a chemical bond between the functional groups on the surface of the glass fiber and the polymer matrix, which was formed as a result of treating the glass fiber surface with silanes, It has been shown that when treated with aminopropyltriethoxysilane, significant functional unprotonated amino groups NH+/NH2+ are formed on the surface of the fibers; such free amino groups, oriented in the direction from the fiber surface, form strong bonds with the matrix polymer. Based on experimental data, the chemical structure of the polymer/glass fiber interface was identified.

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.