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 review begins with a sober assessment of sustainability claims. Insects such as Tenebrio molitor, Acheta domesticus, Locusta migratoria, Alphitobius diaperinus, Bombyx mori and Hermetia illucens offer high feed conversion efficiency, short growth cycles and lower land requirements than conventional livestock, and many species contain all essential amino acids in nutritionally significant amounts. Yet the authors stress that environmental advantages only materialise when the entire production chain is optimised, including rearing substrate, energy use for temperature control, killing method and drying. Insect proteins should therefore be treated as conditional alternatives whose benefits depend on well-controlled systems rather than assumed by default.

Even measuring how much protein an insect contains turns out to be surprisingly tricky. The conventional nitrogen-to-protein conversion factor of 6.25 can overestimate protein content because insect biomass contains nitrogen from chitin and other non-protein compounds. Janssen and colleagues proposed a lower factor of approximately 4.76 for mealworm, lesser mealworm and black soldier fly larvae. Reported values also depend on whether composition is expressed on a fresh-weight or dry-matter basis, and on the developmental stage, rearing diet and processing history of the material. Digestibility adds another layer: in vitro studies show mealworm and cricket proteins can achieve digestibility figures of 79 to 99 percent and favourable DIAAS scores, but these outcomes shift with heat treatment, defatting and chitin reduction, making digestibility a processing-dependent property rather than a fixed species trait.

Processing is where the review’s central framework comes into play. Pretreatments such as killing, blanching, drying, grinding and defatting establish the initial state of the biomass, and each involves trade-offs. Blanching improves microbial and enzyme control but can unfold proteins and promote aggregation that reduces extraction efficiency. Freeze-drying limits thermal damage but is costly, while microwave and hot-air drying scale better yet risk Maillard reactions, lipid oxidation and protein denaturation. Defatting enriches protein and limits oxidation, since residual lipids rich in polyunsaturated fatty acids generate rancid aldehydes such as hexanal and nonanal, but solvent contact and duration can alter protein conformation and downstream recovery. Quantitatively, defatting raised Tenebrio molitor flour from 57.8 to 64.6 percent protein while cutting fat to 2.8 percent, and lifted Hermetia illucens flour from 34.7 to 44.9 percent protein.

Protein recovery routes then diverge sharply. Dry fractionation by milling and sieving is simple and low in water and chemical use, but yields fractions still loaded with lipids, chitin, ash and pigments, making them better suited to bakery and snack applications than to refined functional roles. Alkaline solubilisation followed by isoelectric precipitation boosts purity and yield, but extreme pH can trigger denaturation, browning and unwanted structural changes. Assisted technologies offer further options: ultrasound cavitation disrupts tissues and aggregates, improving extraction yields by 35 to 94 percent in sonicated silkworm pupae, while high-pressure processing increased protein solubility in Protaetia brevitarsis seulensis up to an optimum of 200 megapascals before the benefit declined. No single technology wins outright; the authors insist processing should be designed backwards from the target food.

Post-recovery modification tailors proteins to specific functions, and here the quantitative evidence is striking. Enzymatic hydrolysis of migratory locust protein raised solubility from as low as 10 percent to 55 percent and foamability to 326 percent at pH 3. Cricket hydrolysates reached emulsifying activity indices of up to 32 square metres per gram, compared with 6.23 for defatted cricket flour. But hydrolysis illustrates what the authors call the protein-functional modification dilemma: excessive cleavage weakens interfacial films, releases bitter hydrophobic peptides and, crucially, does not reliably eliminate allergenic epitopes unless proteolysis is extensive, on the order of 60 to 85 percent degree of hydrolysis needed to disrupt major allergens such as tropomyosin. Fermentation offers another route, with fungal fermentation of cricket powder increasing solubility by roughly 20 percent and water-holding capacity from 2.17 to about 2.62 grams per gram, though it demands careful microbiological control.

Application studies show that ingredient form must match product structure. Bread is highly sensitive because insect flour dilutes the gluten network that traps fermentation gases, producing compact crumbs and darker colour, so insects work best as supplementary ingredients. Biscuits, crackers, muffins and protein bars tolerate higher inclusion levels because their quality depends less on gas retention. Extruded snacks sit in between: cricket powder at 12.5 to 15 percent could qualify products as protein sources, but 7.5 percent was recommended to preserve expansion and texture. In meat analogues, insect proteins perform best as complementary fractions within hybrid systems. High-moisture extrusion of insect and soy protein concentrates showed that around 15 to 40 percent insect protein could match the cutting properties of a soy control, while substituting 10 percent of soy protein isolate with cricket powder actually enhanced fibrous anisotropy, although higher levels produced brittle, incoherent extrudates. Three-dimensional printing studies found that pellet fractions of cricket and mealworm at 15 percent gave the best shape fidelity and post-print texture, underlining that fractionation, not the insect species alone, is the controlling design variable.

Liquid foods impose the strictest demands. Beverages require high solubility at acidic pH to avoid sedimentation and cloudiness, making whole insect flours largely unsuitable and pushing formulators toward soluble concentrates and hydrolysates. Consumer testing of mealworm protein shakes identified a rejection threshold of 14.6 percent mealworm content only among blind-tasting participants; health- and sustainability-framed groups showed no comparable threshold, suggesting communication can shift tolerance, though it cannot rescue poor sensory quality. Bioactive peptides add another dimension: cricket hydrolysates produced by microwave-assisted enzymatic hydrolysis showed ACE-inhibitory IC50 values of 0.096 milligrams per millilitre and DPP-IV-inhibitory values of 0.27, better than conventional hydrolysis. The authors caution, however, that these results come from chemical and in vitro enzyme assays and cannot be equated with proven antihypertensive or glycaemic effects in humans.

Safety and regulation complete the picture. Insect biomass can carry Enterobacteriaceae, Salmonella, Listeria, Staphylococcus aureus and spore-forming bacteria, so hurdle-based strategies combining blanching, drying, water-activity control and hygienic handling are essential. Chemical hazards such as mycotoxins and heavy metals depend on rearing substrate, meaning circular production using food-industry side streams requires rigorous contaminant monitoring. Allergenicity remains a critical concern because insects share conserved pan-allergens, including tropomyosin and arginine kinase, with crustaceans, molluscs and house dust mites; one observational study found 73 percent of crustacean- and mite-sensitised patients showed IgE reactivity to recombinant black soldier fly tropomyosin. In the European Union, novel food authorisations are species- and process-specific, as illustrated by the approved partially defatted house cricket powder, which carries mandatory allergen labelling. The review’s conclusion is clear: no single insect ingredient will suit every product. Commercial success will depend on standardised, application-specific ingredients whose processing history, functional performance, safety profile and sensory character are validated together, from raw material to finished food.

Subject of Research: Processing-structure-function relationships in edible insect proteins for food applications

Article Title: Designing edible insect proteins for food applications: Processing-Structure-Function relationships, product performance and safety trade-offs

Article References: Nguyen, C. H., & Truong, D. H. (2026). Designing edible insect proteins for food applications: Processing-Structure-Function relationships, product performance and safety trade-offs. Journal of Agriculture and Food Research, 31, Article 103340. https://doi.org/10.1016/j.jafr.2026.103340

Image Credits: AI Generated

DOI: 10.1016/j.jafr.2026.103340

Keywords: edible insects, insect protein, food processing, protein functionality, allergenicity, food safety, meat analogues, protein hydrolysates, novel foods, sustainable protein, techno-functional properties, consumer acceptance