The study, published in Frontiers in Chemistry by Zijing Wang and colleagues at Xi’an University of Science and Technology, Beijing University of Chemical Technology, and Yan’an University, combined first-principles calculations, spectroscopy, and electrochemical testing to unravel exactly how sarcosine stabilizes the zinc metal anode. The answer, they found, lies in a two-pronged mechanism: the molecule simultaneously restructures the water hydrogen-bond network in the electrolyte and preferentially adsorbs onto the zinc surface, reshaping the interface where the most damaging chemistry occurs.

The core challenge is thermodynamic. In an aqueous zinc-ion battery, the hydrogen evolution potential at pH 5 sits at −0.296 volts versus the standard hydrogen electrode, which is more positive than the zinc redox potential of −0.76 volts. That means water molecules are reduced before zinc ions can plate cleanly onto the anode, generating hydrogen gas, depleting the electrolyte, and corroding the metal. Meanwhile, hydroxide ions produced by water hydrolysis react with zinc sulfate to form insoluble, electrochemically inactive byproducts such as Zn4SO4(OH)6·xH2O, which roughen the electrode surface and accelerate dendrite formation. Left unchecked, these processes culminate in internal short circuits and battery failure.

Sarcosine, also known as N-methylglycine, is a naturally occurring, inexpensive, water-soluble, and biodegradable amino acid. Its compact molecular structure pairs an amino group with a carboxyl group, giving it two distinct chemical handles. Density functional theory calculations revealed a strong molecular polarization: the O–H and N–H hydrogens carry local positive electrostatic potential maxima of 46.21 and 40.57 kcal mol−1 respectively, making them powerful hydrogen-bond donors, while the carbonyl oxygen carries a negative potential of −38.97 kcal mol−1, providing an electron-rich anchor site for zinc ions and for binding to the zinc surface.

Molecular dynamics simulations showed that sarcosine does not dramatically rebuild the primary zinc solvation shell. In a baseline ZnSO4 electrolyte, each zinc ion coordinates with about 5.76 water molecules; adding sarcosine only nudges that number down to 5.74, with a weak Zn2+–O(Sar) coordination number of 0.06. Instead of displacing water from the inner shell, sarcosine works through weaker, subtler interactions—hydrogen bonding with water and preferential adsorption on the electrode. First-principles calculations confirmed that sarcosine binds to the Zn(002) surface with adsorption energies of −1.01 and −0.98 eV for two representative configurations, far stronger than water’s −0.31 eV. This means sarcosine outcompetes water for surface sites, physically blocking the direct adsorption and reduction of water molecules that drive hydrogen evolution and corrosion.

Spectroscopic evidence backed up the picture. Raman measurements of the O–H stretching region between 3,000 and 3,700 cm−1 deconvoluted the water population into three categories: strongly hydrogen-bonded free water at 3,230 cm−1, weakly hydrogen-bonded water at 3,450 cm−1, and non-hydrogen-bonded water at 3,620 cm−1. As sarcosine concentration increased, the fraction of active free water steadily shrank while the inert, additive-restricted fraction grew. Nuclear magnetic resonance confirmed the trend, with the deuterium peak of D2O shifting downfield from 4.702 ppm in neat solvent to 4.72 ppm in the 0.5 M sarcosine electrolyte, indicating progressively tighter binding of water molecules. Fourier-transform infrared spectroscopy showed the O–H stretching vibration shifting to higher wavenumbers and the sulfate vibration moving from 1081.6 to 1084.3 cm−1, both consistent with a weakened water network and reduced zinc–sulfate interaction.

The electrochemical consequences were dramatic. In Zn||Zn symmetric cells, the sarcosine-modified electrolyte sustained stable cycling for over 2,100 hours at 1 mA cm−2, while the baseline electrolyte failed after roughly 50 hours at the harsher condition of 5 mA cm−2 and 5 mAh cm−2. Zn||Cu half-cells achieved an average Coulombic efficiency of 99.7 percent over more than 1,200 cycles, compared with severe fluctuations and failure after about 200 cycles in the unmodified electrolyte. In situ optical microscopy revealed that zinc plating in the baseline electrolyte produced loose, black, dendritic deposits with visible gas bubbles, whereas the sarcosine-containing electrolyte maintained a smooth, flat surface throughout plating and stripping with no bubble formation.

Three-dimensional laser confocal microscopy quantified the improvement in surface morphology. After 100 cycles at 1 mA cm−2 and 1 mAh cm−2, the maximum surface height of zinc anodes cycled in the baseline electrolyte reached approximately 77 micrometers, while those cycled in the sarcosine electrolyte measured only 21 micrometers. After 5 hours of plating at 5 mA cm−2, the contrast was even starker: 118 versus 23 micrometers. Chronoamperometry showed that the deposition current in the baseline electrolyte rose continuously as new active sites formed and dendrites proliferated, while the sarcosine electrolyte reached a stable current quickly after nucleation, indicating uniform and controllable zinc deposition.

Kinetic measurements added further depth. Temperature-dependent electrochemical impedance spectroscopy and Arrhenius analysis showed that the activation energy for zinc deposition dropped from 34.2 kJ mol−1 in the baseline electrolyte to 30.01 kJ mol−1 with sarcosine, confirming a lowered energy barrier for zinc ion reduction. The nucleation overpotential increased from 33.4 to 42.5 millivolts, which paradoxically is beneficial: a higher nucleation barrier promotes the formation of more numerous, finer, and more evenly distributed zinc nuclei rather than coarse, dendritic growth. Tafel polarization measurements showed the corrosion current density falling from 5.42 to 1.11 mA cm−2, an approximately 80 percent reduction, while linear sweep voltammetry revealed that the hydrogen evolution onset potential shifted cathodically by 171 millivolts, from −1.073 to −1.244 volts, meaning substantially more energy is required to trigger gas evolution.

In full cells paired with a ZnI@CNT-AC cathode, the sarcosine electrolyte delivered higher specific discharge capacity across all tested rates and recovered nearly its original capacity when the current was reduced from 8 to 0.1 A g−1. After 24 hours of rest, the modified cell retained 96.87 percent of its capacity, compared with only 73.24 percent for the baseline cell—a stark demonstration of reduced self-discharge through suppressed parasitic reactions. Over 3,000 cycles at 1 A g−1, the full cell retained 90.6 percent of its initial capacity with Coulombic efficiency approaching 100 percent. The researchers note that further validation under high electrode loading, lean electrolyte, and limited zinc excess will be needed to confirm practical viability, but the strategy itself—a simple, green, low-cost amino acid additive that simultaneously tames water reactivity and reshapes the electrode interface—offers a compelling blueprint for the next generation of safe, durable aqueous zinc batteries.

Subject of Research: Sarcosine electrolyte additive for stabilizing zinc metal anodes in aqueous zinc-ion batteries

Article Title: Adsorption-dominated interfacial regulation by sarcosine via hydrogen-bond water modulation for stable Zn metal anodes

Article References: Wang, Z., Ju, H., Zhang, H., Yang, Y., Liu, H., Cao, B., Ding, J., & Xu, B. (2026). Adsorption-dominated interfacial regulation by sarcosine via hydrogen-bond water modulation for stable Zn metal anodes. Frontiers in Chemistry, 14, Article 1986660. https://doi.org/10.3389/fchem.2026.1986660

Image Credits: AI Generated

DOI: 10.3389/fchem.2026.1986660

Keywords: aqueous zinc-ion batteries, zinc metal anode, sarcosine, electrolyte additive, hydrogen evolution reaction, dendrite suppression, hydrogen-bond regulation, interfacial adsorption, energy storage, electrochemistry, density functional theory, zinc corrosion

The appeal is easy to see. Compared with soy protein, rice protein rarely triggers allergic reactions, making it attractive for infant formula and allergy-sensitive consumers. Unlike wheat protein, it contains no gluten, offering a critical alternative for people with celiac disease or gluten intolerance. It also delivers a balanced amino acid profile with high nutritional value, and its raw material is abundant, fast-growing, and efficient in land and water use per unit of protein produced. Yet despite these advantages, natural rice protein has struggled to find a foothold in products such as whipped toppings, plant-based yogurts, and gluten-free baked goods, because it performs poorly at the interfaces where emulsifiers and foaming agents must work.

The root of the problem lies in the protein’s molecular architecture. Rice glutelin, which accounts for roughly 80 percent of the total protein in the grain, is a large, rigid molecule held together by an extensive network of disulfide bonds. In its native state, the hydrophobic regions that would anchor the protein to oil droplets or air bubbles are buried deep inside the folded structure. Solubility can be as low as 1.84 percent, which means the protein tends to clump into large aggregates rather than dispersing evenly and diffusing toward an oil-water or air-water interface. Compounding the difficulty, the protein’s isoelectric point falls between pH 4 and 5, where its net charge approaches zero, electrostatic repulsion collapses, and aggregation and precipitation accelerate.

Why does this matter for food texture? When a protein acts as an emulsifier or foaming agent, it must race to a newly created interface, unfold, and reorganize so that hydrophobic segments face the oil or air phase while hydrophilic segments remain in water. This adsorption process unfolds in stages: diffusion from the bulk liquid, conformational rearrangement at the interface, and finally the formation of a viscoelastic film that physically blocks droplets or bubbles from merging. Rice glutelin’s dense cross-linking and stiff backbone raise the energy barrier for that rearrangement, so the protein cannot complete sufficient unfolding within the limited time available. The result is a loose, defect-ridden interfacial layer with low mechanical strength, unable to resist the drainage and rupture that collapse foams or the coalescence that breaks emulsions.

The review, led by Zhuangpeng Wang and colleagues, systematically maps how physical, chemical, and enzymatic modification strategies can overcome these limitations, and the numbers are striking. Ultrasound treatment, which uses cavitation forces to break non-covalent bonds and partially unfold proteins, boosted foaming capacity by 189.5 percent and emulsifying capacity to 77.1 milliliters per gram in one study, while extending emulsion stability in rice bran protein systems to more than 336 minutes. High hydrostatic pressure, operating at 100 to 600 megapascals, increased the solubility of rice bran protein by up to 76.69 percent without the nutrient losses associated with heat. Extrusion processing raised emulsion stability by 152.82 percent, and simple pH-shifting treatments accelerated both the permeation and rearrangement rates of protein molecules at the interface.

Chemical approaches work on a different principle: they covalently retool the protein’s surface chemistry. Glycosylation, which attaches sugar molecules through the Maillard reaction, improved foaming ability to 180.31 percent by adding hydrophilic groups and steric hindrance that keep molecules from clumping. Deamidation, which converts glutamine and asparagine residues into acidic forms, raised emulsifying capacity to 44.19 square meters per gram by improving solubility. Phosphorylation and acylation similarly reduced particle size and increased surface charge, with succinylation of rice glutelin lifting foaming capacity above 102 percent and foam stability to nearly 98 percent. The authors caution, however, that these methods carry trade-offs: chemical reagents raise cost and regulatory questions, and excessive modification can reduce digestibility or even expose hidden allergenic epitopes.

Enzymatic modification offers a gentler path. Proteases such as papain chop the bulky protein into smaller peptides that diffuse faster and adsorb more readily, achieving emulsifying capacities of 71.45 square meters per gram. Transglutaminase, an enzyme that stitches glutamine and lysine residues together into isopeptide bonds, produced a remarkable 375 percent increase in foaming capacity in rice bran protein by building a stronger, more elastic interfacial network. Laccase, a polyphenol oxidase that requires no cofactors, can cross-link proteins with phenolic compounds under mild conditions. Notably, the review highlights that combining methods often outperforms any single technique: ultrasound paired with alkaline heat treatment shrank rice protein particles to roughly 130 nanometers and pushed emulsion stability to about 360 minutes, while pH-shifting combined with calcium ion induction tripled foaming capacity.

These improvements translate directly into real food applications. In gluten-free baking, where the gas-holding network of gluten is absent, modified rice protein fibers have significantly increased the volume and softness of angel food cakes. In dairy alternatives, hydrolyzed rice glutelin can stabilize coconut milk emulsions against heating and shear stress, and rice protein hydrolysates partially replacing whey protein maintain physical stability while improving digestibility. In plant-based meat, rice protein substituted into extruded meat analogs influenced texture and fibrous structure, and in beverages, glycosylated rice protein resists the heat-induced aggregation and mineral-triggered precipitation that plague natural proteins in coffee creamers and fortified drinks.

The path from laboratory bench to factory floor is not without obstacles. Ultrasound equipment remains expensive and suffers from limited penetration depth at scale, high-pressure systems constrain product size, and enzymatic processes demand precise control to avoid bitter peptides from over-hydrolysis. Chemical modifications require reagent recovery and waste management, and composite strategies involve multi-step processes whose consistency is difficult to maintain industrially. Regulatory frameworks add another layer of complexity: in the European Union, significantly altered proteins may be classified as novel foods requiring full safety assessment by the European Food Safety Authority, while the United States may require generally recognized as safe designation or food additive approval. The review also flags a subtle scientific problem: most studies fail to report the rice cultivar or raw material source they used, even though indica, japonica, and glutinous varieties differ systematically in protein composition, undermining comparability across the literature.

Looking ahead, the authors sketch an ambitious frontier. Gene-editing tools such as CRISPR-Cas9 could redesign the amino acid sequence of rice storage proteins at the source, optimizing hydrophobicity, charge, and flexibility before the grain is even harvested. Molecular dynamics simulations could predict how engineered sequences assemble at interfaces, while machine learning models trained on structure-function databases might automate the design of proteins with tailored interfacial behavior. The most speculative vision involves smart materials: rice protein systems that respond to pH, temperature, ionic strength, or light to switch their interfacial properties on demand, giving food manufacturers dynamic control over emulsion and foam stability during processing and storage. If even a fraction of this agenda succeeds, the humble grain that anchors diets across Asia could become the backbone of a new generation of sustainable, plant-based foods, transforming a byproduct-rich crop into a strategic ingredient for a protein-hungry century.

Subject of Research: Modification strategies to enhance the interfacial adsorption, emulsifying, and foaming properties of rice protein for food applications

Article Title: Modulating the interfacial properties of rice protein to enhance its applicability as an emulsifier and foaming agent in the food industry

Article References: Wang, Z., Huang, X., Zhao, Y., & Wu, L. (2026). Modulating the interfacial properties of rice protein to enhance its applicability as an emulsifier and foaming agent in the food industry. Food Chemistry: X, Article 104554. https://doi.org/10.1016/j.fochx.2026.104554

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104554

Keywords: rice protein, emulsifier, foaming agent, food chemistry, plant-based protein, interfacial adsorption, protein modification, ultrasound, glycosylation, transglutaminase, gluten-free, sustainable food

The research team, led by Chen Li and Tao Yang, focused on wheat gliadin, the alcohol-soluble fraction of gluten that is increasingly explored as a sustainable plant-protein foaming agent. Gliadin is not a single protein but a heterogeneous family of subunits—alpha, beta, gamma, and omega—each differing in molecular weight, cysteine content, hydrophobicity, and conformational character. Alpha-gliadin contains intramolecular disulfide bonds and relatively compact secondary structures, whereas omega-gliadin lacks cysteine entirely and adopts an extended, highly surface-active shape. Most previous studies treated gliadin, or even gluten as a whole, as an averaged component, obscuring the fact that these subunits may respond to polysaccharide partners in fundamentally different ways.

The polysaccharide partner in question, Lycium barbarum polysaccharide or LBP, is a bioactive heteropolysaccharide rich in arabinose, galactose, rhamnose, and galacturonic acid. Its abundance of hydroxyl and carboxyl groups allows it to form hydrogen bonds and electrostatic interactions with proteins, wrapping them in thick hydration shells while decorating protein-coated interfaces with negative charge. LBP has long been studied for antioxidant and immunomodulatory properties, but its role in steering the interfacial assembly of gliadin subunits had never been clarified. The researchers hypothesized that LBP would act through subunit-dependent pathways: compacting and associating alpha-gliadin, while loosening and recharging omega-gliadin.

To test this, the team first separated gliadin into alpha-enriched and omega-enriched fractions using stepwise ethanol precipitation, a classical Osborne-style fractionation exploiting differences in solubility. They then prepared solvent-matched mixtures of each fraction with and without LBP, ensuring that any observed differences could be attributed to the polysaccharide rather than solvent composition. A battery of techniques followed: laser diffraction for particle size, circular dichroism for secondary structure, intrinsic fluorescence and ANS-probe hydrophobicity for tertiary structure, zeta potential for surface charge, sequential extraction for non-covalent interaction forces, SDS-PAGE and size-exclusion chromatography for aggregation state, and pendant-drop tensiometry for interfacial adsorption kinetics.

The structural results were strikingly divergent. In alpha-gliadin, LBP increased beta-sheet content from 42.33 to 45.67 percent while reducing random coil by nearly 15 percent, and it lowered surface hydrophobicity by 17.18 percent—hallmarks of tighter packing and enhanced structural ordering. Hydrogen bonding and hydrophobic interactions both increased, and size-exclusion data showed a rise in polymeric fractions. Omega-gliadin did the opposite: beta-sheet content fell, random coil rose by 16.46 percent, intrinsic fluorescence and surface hydrophobicity increased, and both hydrogen bonding and hydrophobic interactions dropped sharply—by 51.82 and 60.00 percent respectively. Zeta potential shifted more negative in both cases, but the relative change was largest for omega-gliadin, whose absolute charge grew by 31.57 percent, improving colloidal dispersion stability.

These molecular differences translated directly into foam behavior. Alpha-gliadin alone was already an excellent foamer, producing 153.67 percent overrun and a foam half-life of 82 minutes. Adding LBP slightly reduced overrun to 147.00 percent but extended the half-life to 133 minutes—a 62 percent improvement—while cutting the drainage rate by nearly a third. Omega-gliadin, by contrast, was a poor performer, with only 50 percent overrun and a half-life of under 20 minutes. LBP lifted its overrun to 62.33 percent and prolonged its half-life to 32.67 minutes, a nearly 69 percent gain, while simultaneously reducing drainage. Microscopy confirmed the story: alpha-gliadin foams became denser and more uniform, while omega-gliadin’s large, collapsing bubbles gave way to a visibly finer distribution.

Interfacial kinetics explained the mechanism. Alpha-gliadin adsorbed fastest at the air-water interface, with the highest initial adsorption rate and the shortest half-adsorption time of 18.17 seconds, whereas omega-gliadin lagged far behind at 75.10 seconds. After LBP addition, omega-gliadin’s apparent adsorption rate increased and its equilibrium interfacial tension dropped, indicating that the polysaccharide reconstructed its sluggish interfacial behavior. The authors interpret this as a compensatory enhancement: the polysaccharide modestly reinforces the already efficient film of alpha-gliadin but substantially rebuilds the weak film-forming capacity of omega-gliadin, consistent with earlier observations that weaker interface-active proteins benefit most from synergistic polysaccharide partners.

To probe the molecular origins of these divergent responses, the team ran 50-nanosecond all-atom molecular dynamics simulations using representative alpha- and omega-gliadin sequences and a simplified arabinogalactan model of LBP. The simulations showed that LBP drove alpha-gliadin toward a more compact, dynamically stable ensemble—with reduced radius of gyration, solvent-accessible surface area, and backbone fluctuations—and formed 773 intermolecular hydrogen bonds with it, along with a sharp radial distribution peak indicating persistent, close-range contact. Omega-gliadin, in contrast, sampled more expanded, solvent-exposed conformations with elevated flexibility in loop and terminal regions, and formed only 314 hydrogen bonds with the polysaccharide in more transient, diffuse associations. Free-energy landscape analysis confirmed that alpha-gliadin with LBP occupied a localized, low-variability conformational region, while omega-gliadin systems explored broader conformational space.

The authors are careful to note the limits of the computational work: each system was represented by a single trajectory without replicas, the polysaccharide model captures only part of LBP’s structural heterogeneity, and the simulations lacked an explicit air-water interface. The mixed force-field parameterization was not formally revalidated, so the results describe comparative tendencies rather than quantitative binding thermodynamics. Similarly, because interfacial rheology was not measured directly, the improved foam stability cannot yet be pinned to increased interfacial mechanical strength. The experimental foaming results were also obtained under solvent-matched conditions containing 25 percent 1-propanol, required to keep gliadin soluble, so absolute behavior in alcohol-free aqueous systems may differ.

Even with those caveats, the study delivers a conceptually important message for food colloid science: polysaccharide regulation of protein foams operates at the subunit level, and the same molecule can stiffen one protein fraction while flexibilizing another to achieve the same functional goal—longer-lasting foam. As plant-protein formulations replace animal-derived foaming agents across the food industry, this structure-interaction-performance framework suggests that formulators should no longer ask simply whether a protein and a polysaccharide are compatible, but which specific protein subunits are present and how each one responds. Targeted polysaccharide strategies, matched to subunit composition, could become the key to plant-based foams that finally rival their animal-derived counterparts in shelf stability.

Subject of Research: Subunit-dependent stabilization of wheat gliadin foams by Lycium barbarum polysaccharide

Article Title: Subunit-dependent interfacial assembly of wheat gliadin subunits by Lycium barbarum polysaccharide underlies foam stabilization

Article References: Li, C., Wang, B., Yu, H.-Y., Dai, X.-L., & Yang, T. (2026). Subunit-dependent interfacial assembly of wheat gliadin subunits by Lycium barbarum polysaccharide underlies foam stabilization. Food Chemistry: X, 39, Article 104416. https://doi.org/10.1016/j.fochx.2026.104416

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104416

Keywords: wheat gliadin, Lycium barbarum polysaccharide, foam stability, protein-polysaccharide interactions, air-water interface, plant proteins, food colloids, molecular dynamics simulation, interfacial adsorption, alpha-gliadin, omega-gliadin, food chemistry