Together, the contributions describe changes involving protein organization, cell-wall permeability, pectin networks, rheology, yield, and texture. The editorial frames plant-based food as a dynamic soft-matter system whose functional properties emerge from a hierarchy extending from individual molecules to intermediate networks and, ultimately, macroscopic behavior. Plant proteins and polysaccharides can have rigid structures, limited solubility, undesirable off-flavors, and poor texturization under conventional thermal processing.

Replacing animal-derived proteins and fats with plant sources therefore presents scientific difficulties as well as sustainability goals. The proposed alternative is to connect physical changes at one scale with observable properties at another, including mouthfeel, firmness, stability, and texture, rather than treating food processing as a collection of unrelated steps. One review examines ultrasound-assisted structural modification in plant proteins at the molecular and macro-organizational levels.

Its mechanism centers on acoustic cavitation, which generates localized shear forces, microjets, and transient temperature spikes. These effects can disrupt non-covalent interactions, partially unfurl folded polypeptide chains, and expose previously hidden hydrophobic regions. The editorial reports that this molecular realignment can improve solubility, emulsification, and gelation performance.

A second review addresses a wider processing continuum, beginning with the extraction of components from plant biomass and extending to the texturization of the resulting ingredients. It considers the integration of ultrasound with complementary electro-physical technologies in what the editorial describes as multi-technology, green processing cascades. The purpose is to connect the physical principles involved in isolation with the production of ingredients whose structures and techno-functional properties are retained or improved.

Rather than treating ultrasound and other electro-physical methods as isolated alternatives to heat, this perspective places them within coordinated processing lines and considers how multiple physical mechanisms can contribute at successive stages. The collection’s mini-review offers a more focused multiscale analysis of tomato-based matrices subjected to ultrasound or pulsed electric fields. According to the editorial, both approaches can modify cell-wall permeability and interactions within pectin networks without the thermal degradation associated with heating.

These microscopic modifications can affect macroscopic rheological properties and are reported in the tomato work to enhance lycopene bioaccessibility. The contribution therefore illustrates how targeted physical stress can be connected to process efficiency, potential nutritional value, and sensory quality in the same matrix. Its evidence is specific to tomato-based systems, however, and the editorial does not demonstrate that every response observed in those systems will occur at the same level in other plant foods.

The topic’s original research examines a finished plant-based product: tofu. In that study, the authors use multivariate modeling to evaluate the combined effects of thermosonication and coagulant type on tofu matrices. The editorial describes the analysis as a mapping of relationships among physical processing inputs, coagulant chemistry, product yield, and textural profiles.

Because the study evaluates several variables together, it seeks to clarify how processing mechanics and coagulation conditions relate to the formation and performance of a protein network. Its central methodological message is that structural optimization in plant-based foods should not rely only on empirical trial and error, but should instead use an integrated account of interacting physical and chemical inputs. Across these contributions, ultrasound and electro-physical processing are presented as distinct but complementary sources of physical stress.

Ultrasound acts through cavitation-associated mechanical effects, including shear forces and microjets, whereas pulsed electric fields impose localized electrical stress on plant material. In tomato matrices, these treatments are considered together because both can influence cell and network organization. In plant proteins, ultrasound is associated with changes to folded molecular structures and non-covalent interactions.

The soft-matter framework allows researchers to relate these molecular or cellular events to the behavior of gels, emulsions, and other organized structures, and then to properties such as solubility, stability, rheology, and texture. The editorial also places the research topic within the wider push toward sustainable food systems and connects it to the United Nations Sustainable Development Goals on zero hunger and responsible consumption and production. Its argument is that replacing animal-derived food matrices with plant-based alternatives requires more than a change in ingredients; the structures within those ingredients must also be engineered deliberately.

Non-thermal physical methods offer tools for controlling selected features without relying solely on conventional heating. Nevertheless, the editorial is a synthesis of research contributions rather than a clinical, consumer, or industrial performance study, and it does not report human health outcomes, consumer acceptance results, or large-scale manufacturing validation. The strongest conclusion is methodological: improving the texture and function of plant-based foods requires researchers to connect mechanisms across scales and model the interactions among processing variables.

Ultrasound-assisted protein modification, electric-field treatment of plant cells, combined electro-physical processing, and multivariate optimization of tofu demonstrate how this approach can be applied to different structural levels and product systems. The research topic does not establish universal gains in nutritional value, yield, sensory quality, or texture.

Subject of Research: Multiscale modification of plant-food structures using ultrasound and electro-physical processing

Article Title: Editorial: Multiscale analysis of ultrasound-assisted and electro-physical methods for modifying structure–property relationships in plant-based foods

Article References: Lamas, D. L., Lin, Y.-W., & Huang, P.-H. (2026). Editorial: Multiscale analysis of ultrasound-assisted and electro-physical methods for modifying structure–property relationships in plant-based foods. Frontiers in Soft Matter, 6, Article 2019319. https://doi.org/10.3389/frsfm.2026.2019319

Image Credits: AI Generated

DOI: 10.3389/frsfm.2026.2019319

Keywords: plant-based foods, ultrasound processing, pulsed electric fields, food structure, plant proteins, soft matter, tofu texture, tomato matrices, food engineering, Editorial, Multiscale, analysis

The core challenge is architectural. Many plant proteins fold into compact globular shapes stabilized by dense networks of hydrogen bonds, hydrophobic interactions, and disulfide linkages. These bonds provide stability but also bury the functional groups that proteins need to dissolve in water, stabilize emulsions, form foams, and create gel networks. The result is poor solubility, weak interfacial behavior, limited digestibility, and sensory performance that often falls short of animal proteins. The review emphasizes that these constraints operate across a hierarchy of scales, from the molecular conformation of secondary and tertiary structures to the microstructural organization of protein aggregates and the macroscopic properties of gel networks, and it is this multiscale organization that ultimately governs how plant proteins behave in complex food matrices.

Ultrasound processing has emerged as one of the most versatile tools for breaking through these structural barriers. Operating at frequencies between roughly 20 and 100 kilohertz, ultrasound triggers acoustic cavitation, a process in which microscopic bubbles form, grow, and collapse violently within liquid protein suspensions. Each bubble collapse generates localized shear forces, microjets, and shock waves that can disrupt protein aggregates and promote partial unfolding without the extensive thermal damage associated with conventional heating. The review highlights that these mechanical forces primarily target the non-covalent interactions stabilizing protein structure, weakening hydrogen bonds and hydrophobic associations that hold aggregates together.

The structural consequences are measurable and significant. Jambrak and colleagues demonstrated that ultrasound treatment altered the secondary structure of soy proteins, reducing the proportion of alpha-helical structures while increasing random coil configurations, which enhanced protein flexibility and improved solubility and emulsifying capacity. Li and co-workers reported that ultrasound reduced the particle size of pea protein aggregates from 831.6 to 346.7 nanometers under controlled conditions, with the resulting smaller particles exhibiting improved interfacial activity and producing more stable emulsions over time. Hu and colleagues observed that ultrasound treatment increased the availability of free sulfhydryl groups in soy protein isolates, promoting stronger gel formation and improved water-holding capacity. These molecular-level changes cascade upward: disrupted hydrogen bonds drive partial unfolding, which exposes previously buried hydrophobic residues and reactive groups, which then drive controlled aggregation or interfacial adsorption, ultimately determining the macroscopic solubility, emulsification, and gelation properties of the final food product.

Pulsed electric field processing operates through a fundamentally different mechanism. Short bursts of high-voltage electricity, typically between 5 and 50 kilovolts per centimeter with microsecond pulse durations, temporarily disrupt cell membranes through electroporation, creating nanoscale pores that facilitate the release of intracellular proteins without harsh solvents or severe thermal treatments. Barba and colleagues reported that PEF pretreatment improved protein extraction yields from plant materials by approximately 30 percent. Beyond its effects on cellular structures, PEF directly influences protein molecules by interacting with molecular dipoles and charged amino acid residues, causing polarization and reorientation that can disrupt hydrogen bond networks and modify the hydration layer surrounding proteins. The review offers a particularly elegant physical explanation for why alpha-helical segments are preferentially affected: the alpha-helix carries a substantial net dipole moment along its axis because the peptide-bond dipoles are aligned in the same direction, making these segments more strongly coupled to an externally applied electric field than beta-sheet segments, which leave a comparatively small net dipole.

Cold plasma treatment takes yet another approach, acting primarily at the protein surface rather than inducing extensive unfolding throughout the molecular structure. Plasma is a partially ionized gas containing energetic electrons, ions, ultraviolet photons, and reactive oxygen and nitrogen species. When these reactive species interact with exposed amino acid residues, they initiate oxidation-reduction reactions that modify protein side chains. Sulphur-containing amino acids such as cysteine and methionine are especially susceptible, forming sulfoxides, disulfide cross-links, or carbonyl derivatives. Misra and colleagues demonstrated that cold plasma treatment increased the emulsifying activity of soy protein isolates because the introduction of oxygen-containing groups enhanced protein surface polarity and interfacial adsorption. Segat and colleagues reported improved foaming capacity in plasma-treated wheat proteins, while Ji and colleagues showed enhanced solubility and dispersibility of plasma-treated peanut proteins. Because cold plasma modifies surfaces selectively, it allows fine control over interfacial behavior while minimizing structural degradation.

Ohmic heating, which the review carefully distinguishes as an electro-thermal rather than strictly non-thermal technology, passes alternating electric current directly through the food material, generating heat internally through electrical resistance. Unlike conventional heating, where thermal energy transfers gradually from external surfaces inward, ohmic heating produces rapid and uniform volumetric heating throughout the entire food matrix. This minimizes temperature gradients and prevents localized overheating, allowing greater control over protein denaturation and aggregation behavior. Sakr and Liu observed that ohmic heating promoted more homogeneous protein unfolding and network formation compared with conventional thermal methods, with the resulting protein gels exhibiting improved water-holding capacity, elasticity, and structural stability. The review notes that this controlled heating approach is particularly valuable for developing plant-based meat analogues and high-moisture protein systems where uniform network formation is essential for replicating the fibrous texture of animal muscle tissue.

One of the most striking findings of the review is that no single set of processing parameters is optimal across all plant protein sources. Soy and pea proteins are dominated by 7S vicilin and 11S legumin globulins, with the more loosely associated 7S fraction unfolding and solubilising more readily than the disulfide-rich 11S fraction under identical ultrasound treatment. Oat protein, dominated by a compact, highly disulfide-stabilised 12S globulin with unusually high thermal and structural stability, requires substantially higher ultrasound intensities to achieve comparable particle-size reduction and solubility gains. Wheat gluten proteins, being prolamins rather than globulins, respond to ultrasound primarily through changes in disulfide crosslink density and aggregate structure rather than through classical alpha-helix-to-beta-sheet transitions, since their native structure already contains little ordered secondary structure. Faba bean globulins occupy an intermediate position, sharing the 7S/11S architecture of legumes but with a subunit composition that produces a somewhat lower unfolding threshold and a correspondingly higher risk of re-aggregation if treatment is not carefully controlled.

The review also sounds a cautionary note about overprocessing. Beyond a defined favourable range, the same mechanisms that improve functionality at moderate intensity begin to cause functional deterioration. At high acoustic intensities, water sonolysis generates hydroxyl and other free radicals that oxidise newly exposed free sulfhydryl groups back into disulfide bonds, promoting irreversible protein re-aggregation rather than continued unfolding. Excessive cold plasma exposure can over-oxidise surface amino acid residues, producing carbonylation and cross-linking reactions that stiffen the protein surface and reduce interfacial activity. Once excessive aggregation has occurred, the resulting dense aggregates can become less accessible to digestive proteases than either the native protein or the moderately processed form, producing an inverted U-shaped relationship between processing intensity and digestibility. The point at which structural modification becomes detrimental is technology- and protein-source-specific, and is generally reached well before complete protein unfolding or maximal cavitation intensity.

Looking forward, the review identifies computational modelling and machine learning as critical tools for optimizing non-thermal protein processing. Molecular dynamics simulations allow researchers to observe atomic-level structural changes in proteins subjected to mechanical stress, electric fields, or pressure variations, providing insights into how protein folding patterns respond to different processing environments. Machine learning algorithms such as artificial neural networks and random forest models can identify relationships between processing parameters and functional outcomes that may not be evident through conventional statistical analysis, predicting how variations in ultrasound intensity, treatment time, or PEF strength influence solubility, emulsifying capacity, and gel strength. The integration of real-time sensors with machine learning algorithms enables adaptive process control, where processing parameters are adjusted dynamically based on incoming data to ensure consistent product quality despite variations in raw materials. As the review concludes, the most energy-efficient operating point for a given technology is generally the same moderate-intensity window that avoids overprocessing, meaning that energy efficiency and functional quality are not competing objectives but are, in practice, optimised together, bringing the food industry closer to producing plant-based products that are nutritionally balanced, environmentally sustainable, and appealing to consumers.

Subject of Research: Food Science and Soft Matter

Article Title: Multiscale structural modulation of plant proteins via ultrasound and electro-physical processing: from extraction to functional food matrices

Article References: Majeed, N., Younis, K., & Yousuf, O. (2026). Multiscale structural modulation of plant proteins via ultrasound and electro-physical processing: from extraction to functional food matrices. Frontiers in Soft Matter, 6, Article 1881300. https://doi.org/10.3389/frsfm.2026.1881300

Image Credits: AI Generated

DOI: 10.3389/frsfm.2026.1881300

Keywords: plant proteins, ultrasound, pulsed electric fields, cold plasma, ohmic heating, non-thermal processing, food structure, sustainable food systems, protein functionality, multiscale, structural, modulation

The engine of this transformation is acoustic cavitation. When high-intensity sound waves pass through a protein suspension, they force microscopic bubbles to form, grow, and then collapse violently. Each collapse creates a fleeting hot spot of extreme temperature and pressure, accompanied by intense shear forces, shock waves, and microjets of liquid. These micro-events last only microseconds, but they deliver enough localized energy to pry apart the hydrogen bonds, hydrophobic interactions, electrostatic contacts, and disulfide linkages that hold a protein in its compact native shape. Crucially, because the energy is deposited in tiny, transient zones, the bulk of the liquid barely warms, making ultrasound a genuinely non-thermal technology that preserves heat-sensitive nutrients.

The review, authored by Gulcin Yildiz of Igdir University and Gökçen Yıldız of Bursa Technical University, frames ultrasound not as a mere processing aid but as a multiscale structural engineering tool. At the molecular level, cavitation partially unfolds protein chains, exposing functional groups that were previously buried inside. At the supramolecular level, large aggregates are shattered into smaller assemblies, and protein–protein interaction networks reorganize. At the colloidal scale, particle sizes shrink, surface charges shift, and dispersion stability improves. These levels are not independent; they form a continuous cascade in which energy input at the smallest scale ultimately determines whether a protein solution flows, gels, foams, or emulsifies at the largest.

The practical payoffs are striking. In soy protein, combining pH-shifting with ultrasonication produced nano-aggregates of roughly 22 nanometers and lifted solubility from a dismal 1.49 percent to 82.73 percent. Hemp protein isolates treated with ultrasound showed about a 3.7-fold increase in solubility, while lentil proteins gained up to roughly 90 percent more solubility after sonication or thermosonication. Faba bean proteins fragmented from aggregates of 370 nanometers down to 187 nanometers, reaching solubilities above 89 percent, and combining ultrasound with alkaline pH-shifting pushed faba bean solubility from around 12 percent to more than 95 percent. Even mung bean proteins underwent a dramatic micro-to-nano transition, with particles shrinking from 10.37 micrometers to 484 nanometers, improving solubility, emulsification, and oil-holding capacity in the process.

Not every protein responds the same way, however. The review emphasizes that plant protein isolates are heterogeneous mixtures of distinct fractions: soy contains 7S β-conglycinin and 11S glycinin, pea contains vicilin, legumin, and convicilin, and cereals contribute glutelins, prolamins, and albumin–globulin fractions, each with its own structural stability and susceptibility to cavitation. Rice protein, in particular, is a tough case. Its compact, rigid assemblies resist ultrasound-induced unfolding, and meaningful gains require synergistic treatments such as alkaline or thermal assistance. When ultrasound was combined with alkali treatment, rice protein solubility increased by up to roughly 230-fold, one of the largest enhancements reported, but ultrasound alone delivered only modest changes compared with the dramatic responses seen in legumes.

Perhaps the most important conceptual contribution of the review is the idea of an optimal cavitation window. Moderate ultrasound doses promote controlled unfolding, exposing hydrophobic and sulfhydryl groups in ways that enhance interfacial adsorption, gelation, and digestibility. Push past that window, however, and the same exposed hydrophobic regions begin to find each other, driving reaggregation and functional decline. The authors trace this non-linearity to a temporal race: cavitation bubbles collapse in microseconds, but proteins relax and refold over much longer timescales. When sufficient recovery time exists between cavitation pulses, proteins settle into favorable, functional conformations. Under prolonged or continuous sonication, proteins are perturbed again before they can relax, accumulating unfolding and hydrophobic exposure until uncontrolled aggregation wins.

The functional consequences ripple through every property food scientists care about. Emulsifying activity improved by roughly 1.5 to 1.7 times in hemp protein, and pea proteins formed nanoemulsions around 198 nanometers with improved oxidative stability. Lentil proteins stabilized high internal phase emulsions with smaller droplets and better rheological stability, while faba bean proteins produced oil-in-water emulsions with droplets below 0.4 micrometers, suitable as clean-label emulsifiers. Gelation benefited too: moderate cavitation fostered dense, elastic networks stabilized by hydrophobic interactions, hydrogen bonding, and disulfide linkages, raising gel hardness, water-holding capacity, and storage modulus in soy, chickpea, mung bean, and faba bean systems. Excessive sonication, by contrast, produced porous, weak gels with poor viscoelasticity.

Nutrition stands to gain as well. By loosening protein structure and exposing cleavage sites, ultrasound makes plant proteins more accessible to digestive enzymes, enhancing gastrointestinal hydrolysis and the release of bioactive peptides with antioxidant and antihypertensive properties. Rice protein digestibility reached approximately 96.9 percent under optimized ultrasound-assisted pretreatment, and chickpea proteins showed increased enzymatic accessibility along with improved antioxidant activity and gut microbiota modulation. Ultrasound also strengthens protein–biopolymer interactions: sonicated proteins form more stable complexes with polysaccharides such as pectin and inulin, and covalent conjugates with polyphenols such as curcumin and chlorogenic acid, opening routes to encapsulation systems and functional ingredients with enhanced antioxidant activity.

The technology also pays dividends upstream. Ultrasound-assisted extraction disrupts cell walls, improves mass transfer, and boosts solvent penetration into protein-rich plant matrices, cutting extraction time, solvent use, and energy consumption relative to conventional methods. Hemp seed protein extraction yields rose up to 2.1-fold, chickpea protein recovery increased by up to 47.28 percent when ultrasound was combined with pulsed electric fields, and pumpkin seed proteins showed the highest yields under alkaline extraction assisted by ultrasound. The review cautions, though, that excessive cavitation during extraction can trigger aggregation, oxidation, or loss of nutritional quality, so the same optimal-window logic applies to recovery processes as to functional modification.

Scaling all of this from the laboratory bench to the factory floor remains the central challenge. The authors identify persistent obstacles, including a lack of standardization of ultrasound parameters across different systems, incomplete understanding of energy efficiency and heat dissipation at industrial scale, matrix-dependent variability in product functionality, and limited real-time monitoring of structural transitions during processing. Scale-up often produces non-uniform energy distribution, undermining reproducibility. Their roadmap for the future includes integrating ultrasound with complementary technologies such as pulsed electric fields, cold plasma, and high-pressure processing; developing in situ monitoring tools that track unfolding and aggregation as it happens; deploying multiscale computational modeling alongside advanced spectroscopy; and designing continuous-flow ultrasound reactors with improved acoustic uniformity. If those pieces come together, the same sound waves that once seemed a niche laboratory trick could become the precision instrument that turns humble peas, beans, and seeds into the next generation of high-performance plant-based foods.

Subject of Research: Ultrasound-assisted multiscale structural modification of plant proteins and its effects on functionality

Article Title: Ultrasound-assisted multiscale structural engineering of plant proteins: mechanisms and structure–property relationships

Article References: Yildiz, G., & Yıldız, G. (2026). Ultrasound-assisted multiscale structural engineering of plant proteins: mechanisms and structure–property relationships. Frontiers in Soft Matter, 6, Article 1893101. https://doi.org/10.3389/frsfm.2026.1893101

Image Credits: AI Generated

DOI: 10.3389/frsfm.2026.1893101

Keywords: plant proteins, ultrasound, acoustic cavitation, food processing, solubility, emulsification, gelation, digestibility, soy protein, pea protein, sustainable food, non-thermal processing

Protein-glutamine glutaminase, often abbreviated PGG, belongs to a family of enzymes that modify glutamine residues within proteins. When applied to plant proteins such as those from soy, pea or wheat, it can convert glutamine side chains into glutamic acid, changing the charge profile of the protein and, in turn, its solubility, emulsifying capacity and gel-forming behavior. That matters enormously for the fast-growing plant-based food sector, where manufacturers struggle to replicate the mouthfeel and stability that animal proteins deliver naturally. An enzyme that can be sprinkled into a formulation to improve functionality without chemical additives is an attractive proposition, but only if it can be manufactured at scale, consistently and affordably.

The Barcelona group, led by Clàudia Lliso-Pascual, Sergi Abad, Marc Carnicer and Antoni Planas, working between the Institut Químic de Sarrià of Universitat Ramon Llull and the biotechnology company CYGYC BIOCON, chose Bacillus subtilis as their production host for good reason. This Gram-positive bacterium is famous for secreting proteins directly into the culture medium, a trait exploited for decades in the industrial production of enzymes for detergents and food processing. Secretion simplifies purification dramatically: instead of cracking open cells and separating a soup of intracellular contaminants, manufacturers can simply collect the culture supernatant, in which the target protein is already enriched. Yet B. subtilis does not secrete every protein equally well, and finding the right combination of genetic controls is largely a matter of trial and error.

To bring order to that trial and error, the researchers constructed a modular secretion platform based on Golden Gate cloning, a DNA assembly method that allows genetic parts to be swapped in and out of a common backbone with standardized overhangs. In their architecture, a promoter, which controls how strongly the gene is transcribed, and a signal peptide, which directs the growing protein through the secretion machinery, could be combined systematically in a single construct design. This meant that dozens of promoter-signal peptide pairings could be screened under identical conditions, with the gene of interest held constant. Such standardization is the essence of modern synthetic biology: rather than redesigning each construct from scratch, engineers assemble variants like interchangeable modules and let the data decide which configuration wins.

The screening combined a reporter assay with direct measurement of enzyme activity, allowing the team to identify which combinations genuinely delivered functional protein to the medium rather than merely producing transcripts. The clear winner was a configuration pairing the Pgrac100 promoter with the amyQ signal peptide, a signal sequence derived from the alpha-amylase gene that has a long track record in Bacillus secretion systems. In the laboratory strain B. subtilis 168, this construct supported robust secretion of the PGG enzyme from Chryseobacterium proteolyticum, designated CpPGG. Intriguingly, the secreted protein emerged as an inactive proenzyme, and the host bacterium itself carried out the maturation step, processing the proenzyme into its active form through its own extracellular proteases.

That host-mediated activation initially looked like a convenient bonus, but it became a liability at scale. When the researchers moved their best construct into 3-liter batch bioreactors running on rich medium, the culture reached 2.9 units per milliliter of enzyme activity in the supernatant, a respectable starting point for a difficult-to-secrete enzyme. However, when they shifted to fed-batch cultivation in a chemically defined medium, a strategy used industrially to push cell densities and product titers higher, a new problem surfaced. The very proteases that B. subtilis uses to mature the proenzyme began to degrade the accumulated protein, and extracellular proteolysis emerged as a major limitation under high-cell-density conditions. In other words, the same biology that activated the enzyme also destroyed it.

The solution was conceptually elegant: decouple secretion from activation. The team transferred their construct into B. subtilis KO7-S, a protease-deficient strain that has been engineered to lack many of the extracellular degradative enzymes that plague protein production in this organism. The strain was kindly provided by Dr. Jordi Ferrando and Prof. Pere Picart of the University of Barcelona, whose expertise in Bacillus biology and transformation supported the work. In KO7-S, the non-processed proenzyme accumulated stably in the culture supernatant, protected from the proteolytic buzz-saw that had undermined production in strain 168. The trade-off was that the accumulated protein was inactive, but that turned out to be a manageable problem rather than a fatal one.

With the proenzyme safely stockpiled outside the cells, the researchers activated it on their own terms. They treated the supernatant with a controlled in vitro activation step using a food-grade neutral protease, an enzyme acceptable for use in food processing, to cleave the pro-peptide and unleash the catalytic activity. This controlled approach yielded 12.8 plus or minus 0.8 units per milliliter of supernatant, a more than fourfold improvement over the batch bioreactor result in the protease-rich host. Just as importantly, the decoupling strategy gives manufacturers precise control over when and how the enzyme becomes active, which simplifies quality control and avoids the unpredictable mixture of intact and degraded protein that plagued the earlier system.

The broader significance of the study lies less in any single number than in the engineering logic it demonstrates. Efficient PGG production, the authors conclude, requires coordinated control of three distinct processes: secretion, extracellular stability and proenzyme activation. Each of these can be optimized independently, and the modular platform makes that optimization systematic rather than ad hoc. The same Golden Gate architecture could, in principle, be applied to other industrially interesting enzymes that suffer from poor secretion or proteolytic degradation in Bacillus hosts, turning the platform into a general-purpose chassis for extracellular protein production. The work also highlights the value of food-grade solutions throughout the process, from the neutral protease used for activation to the generally recognized safety profile of B. subtilis itself.

For the plant-based food industry, the prospect of a reliable, scalable supply of protein-glutamine glutaminase could accelerate the development of next-generation meat and dairy alternatives with improved texture, solubility and nutritional performance. For bioprocess engineers, the study offers a textbook example of how modular cloning, host strain selection and bioreactor strategy must advance together: a brilliant genetic construct is worthless if the fermentation destroys its product, and a high-titer fermentation is worthless if the protein it yields is inactive. The Barcelona team’s platform, funded in part by an industrial doctorate grant from the Catalan government’s AGAUR agency, bridges those worlds, and its open-access publication means that other laboratories can immediately adopt and extend the modular design. As demand for functional plant proteins continues to climb, engineered microbial factories like this one are likely to play an increasingly central role in feeding the world’s appetite for sustainable protein.

Subject of Research: Modular secretion engineering in Bacillus subtilis for scalable production of protein-glutamine glutaminase

Article Title: A modular secretion platform in Bacillus subtilis enables scalable production of protein-glutamine glutaminase

Article References: Lliso-Pascual, C., Abad, S., Carnicer, M., & Planas, A. (2026). A modular secretion platform in Bacillus subtilis enables scalable production of protein-glutamine glutaminase. Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-026-14008-4

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14008-4

Keywords: Bacillus subtilis, protein-glutamine glutaminase, protein secretion, Golden Gate cloning, modular cloning, proenzyme activation, bioreactor cultivation, plant proteins, food-grade enzymes, protease-deficient strains, synthetic biology, industrial biotechnology

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