Biology subjects

Dadmohammadi, Y.

Publications and source records attributed to Dadmohammadi, Y..

5 recordsLinked to original sources

bioRxiv2026

Ethanol-assisted core-shell microparticles for enzyme stabilization with precise size control

In vegetarian diets, phytate is known to disrupt the adsorption of minerals. Fortifying foods with phytase, a therapeutic enzyme known to mitigate phytate, might increase the uptake of important nutrients. Phytase is susceptible to environmental stress such as heat and acidic conditions encountered during food processing. Therefore, we developed and optimized a core-shell microparticle composed of a phytase-chitosan core and a shell consisting of cross-linked alginate-{kappa}-carrageenan. Ethanol was used to precipitate the microparticles, and the ethanol concentration was optimized along with the chitosan and phytase ratio and the alginate-carrageenan concentration, to form stable core-shell microparticles. The optimized core-shell microparticles have a loading capacity of 32.7% with a high encapsulation efficiency of 80.3% and uniform micro-size with a diameter of 3.2 {micro}m and a poly-dispersity index of 0.178. Loaded phytase retained 62.7% enzymatic activity after heat treatment and digestion conditions. These results indicate that core-shell microparticles are suitable for retaining enzyme activity within the food matrix under typical food processing conditions. HighlightsO_LIDevelopment of size-controlled core-shell microparticles to protect phytase C_LIO_LIPhytase-chitosan microparticles are surrounded by an alginate-{kappa}-carrageenan shell C_LIO_LIOptimization achieved 32.7% loading capacity with a uniform size of 3.2 {micro}m C_LIO_LICore-shell microparticles retained 62.7% enzyme activity after heat and digestion C_LIO_LIPhytase powder (2 mg) is required for a single maize meal C_LI

biochemistry↗

bioRxiv2026

Iron-mediated assembly of lactoferrin-alginate composites for iron encapsulation and structural stabilization

Ternary composite systems formed by lactoferrin (LF), sodium alginate (Alg), and Fe(II) were designed to investigate their potential as an iron delivery platform with enhanced protein stability. The ternary LF-Alg-Fe (LAF) composites demonstrated distinct structures depending on the LF to Alg ratio and the Fe(II) concentrations. At an LF to Alg ratio of 8:2 and final Fe concentrations between 20-30 mM, the system formed complexes stabilized by electrostatic interactions. Whereas Alg-rich formulations formed hydrogels stabilized by Alg-Fe(II) egg-box cross-linking. Rheological analysis and swelling behavior indicated a higher mechanical strength in LF-rich complexes and stronger network integrity in Alg-rich hydrogels, while intermediate LF/Alg ratios showed weaker structures overall. Fourier-transform infrared spectroscopy (FTIR) spectra showed no changes in functional groups or polymer structures after composite formation, confirming composite formation via non-covalent interactions. Thermal studies indicated that these ternary systems improved LF stability, evidenced by preserved secondary structure after heating using circular dichroism (CD), and an increased denaturation temperature compared with free LF in differential scanning calorimetry (DSC). In addition, in LF-rich formulations the Fe(II) release in aqueous solution was [~]50% while in Alg-rich formulations it was much lower (< 10%). LF-Alg-Fe composites exhibit distinct structures governed by protein-polysaccharide interactions and iron-mediated cross-linking, providing a potential strategy for protein stabilization and iron fortification in food systems.

biochemistry↗

bioRxiv2025

Improving Thermal and Gastric Stability of Phytase via pH Shifting and Coacervation: A Demonstration of Bayesian Optimization for Rapid Process Tuning

Phytase (phyA) breaks down phytate, which can help with nutrient absorption in a plant-based seed diet or high-phytate food. Unfortunately, it is prone to denaturation at food preparation temperatures and is easily inactivated by pepsin during gastric digestion. To protect phyA for use in high-temperature processes (100 {degrees}C) and gastric digestion, chitosan (CS) was used to complex phyA. Bayesian optimization, a machine learning technique, was used to demonstrate how to expedite the optimization process. Thermal stability of the optimized complex increased from 20% (Control: phyA in the native state) up to 74% at 4:1 CS to phyA (CS-phyA) complex and 52% at the 1:1 CS-phyA complex as measured by phytase activity assay. Chitosan complexation also improved the retention of enzyme activity after thermal and gastric digestion by 13-fold, retaining residual activity at 40% for the 4:1 CS to phyA and 22% for the 1:1 CS-phyA complexes compared to the enzyme itself, which only retained 3% residual activity. Molecular docking and circular dichroism were used to investigate the underlying interaction mechanism between CS and phyA and the secondary structure of the enzyme after heat treatment. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) confirmed the complexation of phyA with CS and revealed complex morphology. With improved enzyme stability, there is great potential for efficiently expanding phytase applications in a high plant-based seed food matrix. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=121 SRC="FIGDIR/small/649602v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@889b76org.highwire.dtl.DTLVardef@969ed3org.highwire.dtl.DTLVardef@953e55org.highwire.dtl.DTLVardef@2f5864_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThermal stability of phytase improved from 20% to 74% using chitosan C_LIO_LIpH shifting increased enzyme complexation efficiency and thermal stability (100 {degrees}C) C_LIO_LIBayesian optimization (BO) is a promising optimization tool for complexation conditions C_LI

biochemistry↗

bioRxiv2025

Core-Shell Hydrogel System to Protect the Enzyme Activity of Phytase from Environmental Stress

Fortification of phytase from Aspergillus niger (phyA) in a vegetarian diet is a practical strategy to solve mineral deficiencies induced by the presence of phytate. To protect phyAs activity and retention from environmental stress such as heat and acidic conditions, we evaluated the use of a core-shell hydrogel bead, where the core is composed of a phyA-chitosan complex, and the shell is formed by cross-linking alginate with {kappa}-carrageenan. The phyA loading capacity is 52.2%, with high encapsulation efficiency (82.6%). When forming the hydrogel beads, a needle diameter of 0.5 mm can create a 2.5 mm bead. The beads were found to remain intact during dehydration under a vacuum at 30 . The formed hydrogel beads protected 79.7% of the phyA activity after heating at 100 {degrees}C for 12 min. The beads protected their cargo against salt, pH changes, and protease. These results suggest that core-shell beads are suitable for protecting enzyme activity against various processing stresses, which makes them useful as a delivery method for phytase in food applications.

biochemistry↗

bioRxiv2025

Improved Thermal Stability of Lactoferrin and Oxidative Stability of Iron(II) Sulfate by Co-encapsulation with Low-Methoxyl Pectin

Complex coacervates between bovine lactoferrin (LF) and low-methoxyl pectin (LMP) were prepared to encapsulate and deliver Fe(II) as an iron fortification ingredient in food, with the goal of enhancing the protein thermal stability and minimizing Fe(II) oxidation. The impact of pH and biopolymer ratio was investigated in terms of complex yield and iron encapsulation efficiency. The thermal stability of LF at 95 {degrees}C was determined by changes in turbidity, particle size, and LF retention by HPLC. The interaction between LF and LMP prevented thermal aggregation and circular dichroism analysis showed the complexation preserved the secondary structure of the protein. LF-LMP-Fe complexes contained 28-74 mg g-1 of total iron depending on the pH of formation, with <5% of the Fe released at neutral pH. The complex coacervation system shows promise as a thermally stable ingredient for iron delivery and food fortification.

biochemistry↗