Beyond Polysaccharides: Multifunctional Roles of Plant‐Derived Conjugates in Sensory Enhancement and Food Quality Improvement

ABSTRACT

In plant‐based foods, polysaccharides rarely exist in isolation. During plant growth, processing, and storage, they can bind to or associate with proteins, polyphenols, lipids, metal ions, and small molecules via covalent or non‐covalent interactions, forming plant‐derived polysaccharide conjugates (PPCs). These conjugates play important roles in determining food structure, sensory attributes, and nutritional functionality. Although many studies have focused on purified polysaccharides or model biopolymer systems, naturally occurring PPCs in plant‐based foods and their multifunctional roles remain insufficiently explored. This review discusses PPCs formed within plant tissues or generated during food processing, summarizing their major types, structural features, and formation pathways, and highlighting how conjugation modulates conformation, charge distribution, hydration, and self‐assembly. Particular attention is given to their roles in regulating color stability, aroma generation and retention, taste perception (including bitterness masking and astringency reduction), and texture formation in foods such as wines, yogurts, low‐fat creams, plant‐based meat analogs, and active packaging films. In addition, their contributions to oxidative stability, gut microbiota modulation, glycemic response, and antitumor potential are discussed from a food science perspective. Finally, current analytical challenges, regulatory considerations, and technological limitations that hinder scale‐up and industrial application are critically evaluated. By linking PPC structure with effects on taste, nutrition, and processing behavior, this review highlights their potential for developing foods that are healthier, more stable, and more palatable.

Abbreviations

5‐HMF

5‐hydroxymethylfurfural

Akt

protein kinase B

AMPK

AMP‐activated protein kinase

AX

arabinoxylan

BLG

β‐lactoglobulin

BSA

bovine serum albumin

BSP

Bletilla striata polysaccharide

cAMP

cyclic adenosine monophosphate

CDI

N,N‐carbonyldiimidazole

CF

citrus flavonoids

Cr (III)

chromium (III)

DEX

dextran

DOP

Dendrobium officinale polysaccharide

DSPE

1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine

EGC

epigallocatechin

EGCG

epigallocatechin gallate

GAE

gallic acid equivalent

GSK‐3β

glycogen synthase kinase‐3β

HIPE

high internal phase emulsion

HSHE

high‐shear homogenization extraction

HSP

hemp seed protein

HWE

hot water extraction

IFN‐γ

interferon‐γ

IgE

immunoglobulin E

IL‐2

interleukin‐2

IL‐6

interleukin‐6

JAK2

Janus kinase 2

LBP

Lycium barbarum polysaccharide

MAE

microwave‐assisted extraction

MAPK

mitogen‐activated protein kinase

MC

myricetin

MMP‐2

matrix metalloproteinase‐2

MMP‐9

matrix metalloproteinase‐9

MyD88

myeloid differentiation primary response 88

NF‐κB

nuclear factor kappa B

NK

natural killer

NMR

nuclear magnetic resonance

PI3K

phosphoinositide 3‐kinase

PLE

pressurized liquid extraction

PPCs

plant‐derived polysaccharide conjugates

PWE

pressurized water extraction

ROS

reactive oxygen species

SCFAs

short‐chain fatty acids

SeNPs

selenium nanoparticles

SFE

supercritical fluid extraction

SP

soy peptide

SPC

soybean lecithin

SPE

solid‐phase extraction

SPI

soy protein isolate

STAT3

signal transducer and activator of transcription 3

TLR2

Toll‐like receptor 2

TLR4

Toll‐like receptor 4

TNF‐α

tumor necrosis factor‐α

UMAE

ultrasound–microwave combined extraction

1. Introduction

Plant‐derived polysaccharides are structurally diverse biopolymers whose properties depend on their composition and structure (J. Li et al. ²⁰²⁵). In plant matrices and food systems, they often occur in association with other components rather than as isolated carbohydrates. Instead, they are commonly associated with proteins, polyphenols, lipids, metal ions, pigments, and other small molecules. During plant growth, processing, and storage, these associations can develop through covalent and non‐covalent interactions, forming plant‐derived polysaccharide conjugates (PPCs) with distinct structural and functional properties (Wan et al. 2025). These associations give rise to PPCs, which may exhibit physicochemical and biological properties that differ from those of purified polysaccharides. For example, the antioxidant activity of water‐extracted polysaccharides from citrus and mushrooms has been suggested to be largely attributable to associated phenolic and protein components rather than to the carbohydrate backbone alone (Surin et al. 2020). Therefore, PPCs should be considered complex molecular assemblies rather than simple polysaccharide fractions.

Although PPCs are increasingly recognized as important components in plant‐based foods, they remain insufficiently integrated into current food science frameworks (Liang et al. 2025). Previous reviews have mainly focused on purified polysaccharides, artificially constructed food‐grade covalent complexes, or polysaccharide‐based nutraceutical delivery systems (Liu et al. 2017). These studies have provided valuable information on biopolymer complexes, but they have not fully addressed naturally occurring PPCs or processing‐induced PPCs in real food matrices. In particular, the roles of PPCs in sensory formation, food stability, nutrient bioaccessibility, and biological activity have not been comprehensively summarized from a food science perspective. This gap limits the understanding of how PPCs contribute to the quality and functionality of complex food systems.

From a food quality perspective, PPCs can influence color, aroma, taste, texture, oxidative stability, and consumer acceptance (Narayan et al. 2025). Their interactions with pigments, volatile compounds, tannins, bitter substances, proteins, and lipids may stabilize color, retain aroma, reduce bitterness and astringency, improve emulsion stability, regulate texture, and delay lipid oxidation (Yu et al. 2025). For instance, polyphenol–polysaccharide conjugates can reduce wine astringency by modulating tannin‐related interactions (Yan et al. 2025). In contrast, polysaccharides conjugated with polyphenols or lipids can improve emulsification, palatability, and shelf‐life stability (Keramat et al. 2023). PPC‐based delivery systems, such as soy protein–soy polysaccharide nanogels, can also enhance folic acid stability and controlled release under gastrointestinal conditions (Sun et al. 2022). These examples indicate that PPCs are multifunctional contributors to both sensory quality and nutritional performance.

Despite these promising applications, the mechanisms underlying conjugate formation remain poorly understood, and the relative contributions of different interactions are difficult to quantify. In particular, naturally self‐assembled conjugates offer great potential but remain underexplored. To address these gaps, this review adopts a broad definition of polysaccharide conjugates, encompassing both covalent and non‐covalent systems. For clarity, it distinguishes between naturally occurring PPCs, which are present in plant tissues or native matrices before processing, and processing‐induced PPCs, which arise or undergo structural alteration during processing, storage, or preparation. This review summarizes the classification, formation, structural features, extraction and synthesis, sensory effects, biological activities, and food applications of PPCs, highlighting their multifunctional roles in plant‐based foods.

2. Classification and Structural Features

Polysaccharides are commonly classified as homopolysaccharides or heteropolysaccharides according to the types of sugars they contain. However, this classification alone cannot explain how they interact with other food components or function in complex food systems. Therefore, this review classifies PPCs according to their interaction partners and the mechanisms that stabilize the complexes. Particular attention is given to structural features such as hydroxyl and carboxyl groups, uronic acid content, molecular weight, branching degree, charge density, and chain flexibility. These features influence the interactions of polysaccharides with proteins, peptides, polyphenols, lipids, metal ions, pigments, flavor compounds, and other small molecules through hydrogen bonding, electrostatic attraction, hydrophobic association, coordination, or covalent bonding. This classification better explains the binding, solubility, and interfacial properties of PPCs, as well as their roles in food stability, sensory quality, texture, and nutrient delivery (Figure 1).

FIGURE 1.

The classification and structural basis of representative polysaccharide conjugates.

2.1. Polysaccharide–Protein/Peptide Conjugates

2.1.1. Polysaccharide–Protein Conjugates

Polysaccharide–protein conjugates are formed through non‐covalent or covalent interactions. In food systems, non‐covalent assemblies are mainly driven by electrostatic interactions, hydrogen bonding, and hydrophobic forces. Covalent conjugates are typically formed via Maillard‐type glycation, enzyme‐mediated cross‐linking, or chemical cross‐linking reactions. Although individual systems differ in composition and processing conditions, their formation generally follows a comparable sequence: molecular recognition, intermolecular association, stabilization by specific interactions, conformational rearrangement, and the development of interfacial films, particulate structures, or three‐dimensional networks.

The type of interaction determines how the resulting complexes are structured and organized. Non‐covalent bonds can easily change or dissociate in response to pH, salt concentration, and temperature. This makes them suitable for controlled release and sensory regulation. In contrast, covalent conjugates are more stable and better able to withstand food processing conditions. For example, arabinoxylan (AX) from cereal byproducts can conjugate with soybean protein under peroxidase and transglutaminase treatment, leading to reduced alpha‐helix content, increased beta‐sheet formation, and a denser, more ordered gel network (Gao et al. 2024). In Maillard‐type systems, amino groups of proteins react with carbonyl groups of reducing sugars to form stable glycopeptide‐linked structures (Zheng et al. 2024). These structural changes can relax or partially unfold protein tertiary structures, expose hydrophobic domains, and generate additional binding sites.

The structural features of the polysaccharide component further regulate the strength and stability of protein–polysaccharide assemblies. Polysaccharides rich in hydroxyl, carboxyl, or uronic acid groups can form stable complexes with proteins, especially under acidic conditions where electrostatic attraction is favored (Shen et al. 2024). Polysaccharides with abundant glucuronic acid residues and high negative charge density can readily form electrostatic complexes with positively charged proteins, thereby establishing stable network structures (Warnakulasuriya and Nickerson 2018). Furthermore, Capek et al. (2015) observed new FT‐IR bands associated with glucuronic acid COOH groups and phenolic compounds after protonation, indicating interactions among carbohydrate, phenolic, and protein components. This example illustrates that protein–polysaccharide conjugates in plant‐derived matrices may contain multiple interacting components rather than simple binary associations.

These changes improve the performance of PPCs in food systems. Protein–polysaccharide conjugates often show marked changes in particle size, viscosity, surface activity, and interfacial stability, which translate into improved emulsification, foaming, and thermal resistance in complex food matrices. Maillard‐type protein–polysaccharide conjugates are particularly effective at stabilizing oil‐in‐water emulsions because they can form thick and cohesive macromolecular layers around oil droplets. These interfacial layers provide steric and electrostatic repulsion that helps suppress flocculation, coalescence, and creaming during pH shifts, heating, increased ionic strength, and freeze–thaw cycles (Nooshkam et al. 2023).

Overall, protein–polysaccharide conjugates are promising structural modifiers and stabilizers for emulsions, foams, gels, sauces, beverages, and encapsulated delivery systems. However, their design should be guided by the intended food application rather than by conjugation efficiency alone. Reversible non‐covalent complexes may be more appropriate for stimulus‐responsive release, oral‐phase interactions, or taste modulation, whereas covalent conjugates are better suited to products requiring long‐term storage stability, thermal tolerance, and robust interfacial protection. This distinction provides a clearer basis for selecting protein–polysaccharide systems in plant‐based and functional food formulations.

2.1.2. Polysaccharide–Peptide Conjugates

Polysaccharide–peptide conjugates are similar to protein–polysaccharide conjugates, but they have distinct structures and properties. Because peptides have shorter chain lengths, lower conformational complexity, and more defined sequence motifs than proteins, their interactions with polysaccharides are often more dependent on amino acid composition, charge distribution, hydrophobicity, and terminal functional groups. The peptide sequence affects how these conjugates assemble, behave at interfaces, and deliver biological functions in food systems (Prommakool et al. 2011). These conjugates can be formed through both covalent and non‐covalent interactions. Covalent coupling commonly involves amide, ester, imine, or thioether linkages, whereas non‐covalent assembly is mainly driven by electrostatic attraction, hydrogen bonding, and hydrophobic interactions (Ghelichi et al. 2025; Mohan et al. ²⁰²²). Through these interactions, peptide fragments may be grafted onto polysaccharide backbones or associated with polysaccharide chains to modify molecular weight, charge density, chain flexibility, and spatial conformation (Olech et al. 2023). As a result, polysaccharide–peptide conjugates can form compact self‐assembled networks, interfacial layers, or nanoscale delivery structures, depending on the polysaccharide source, peptide sequence, pH, ionic strength, and component ratio.

From a functional perspective, polysaccharide–peptide conjugates are valuable because they combine the hydration capacity, biocompatibility, and structural stability of polysaccharides with the sequence‐specific functions of peptides. Peptide domains can provide different functional groups, including hydrophobic patches, charged residues, antioxidant groups, metal‐binding sites, and receptor‐recognition motifs. In contrast, the polysaccharide component improves water solubility, protects peptides from degradation, and controls their release. Zhou et al. (2021) noted that polysaccharide–protein and polysaccharide–peptide conjugates can improve solubility, reduce immunogenicity, and enhance delivery performance compared with native proteins or peptides. For food applications, however, these advantages should be interpreted in relation to matrix stability, digestion, sensory effects, and food‐grade processing rather than only biomedical delivery performance.

Therefore, the main distinction between polysaccharide–protein and polysaccharide–peptide conjugates lies in their structure–function orientation. Protein–polysaccharide conjugates are generally more suitable for matrix stabilization, emulsification, foaming, gelation, and texture development because proteins provide larger interfacial and network‐forming domains. In contrast, polysaccharide–peptide conjugates are better suited for introducing defined bioactive motifs, designing digestion‐responsive carriers, and constructing compact self‐assembled systems. Both systems share common formation principles, including charge‐driven association, covalent coupling, molecular rearrangement, and network development, but peptide‐based conjugates offer greater sequence‐level tunability. This feature makes them promising, although still underexplored, candidates for functional foods, bioactive delivery, and targeted modulation of food structure and digestion.

2.2. Polysaccharide–Lipid Conjugates

In plant‐based foods, polysaccharides can interact with lipids, helping to regulate their distribution, stabilize interfaces, and maintain the structural integrity of the food matrix. Two representative forms are particularly relevant: starch–lipid inclusion complexes and polysaccharide‐modified lipid carriers. The former is mainly governed by non‐covalent inclusion complexation and hydrophobic association within starch helices (Yuldasheva et al. 2021). In contrast, the latter relies more on interfacial adsorption, steric stabilization, electrostatic interactions, or covalent surface coupling. Distinguishing between these two forms helps clarify why polysaccharide–lipid systems can influence both texture‐related properties and the stability, retention, and delivery of lipid‐soluble components.

In starch–lipid inclusion complexes, amylose can adopt a left‐handed helical conformation during heating and cooling, with hydrophilic groups facing outward and hydrophobic cavities accommodating fatty acids or monoacylglycerols. This process promotes the formation of V‐type crystalline structures and modifies gelatinization, retrogradation, digestibility, and texture (Chao et al. 2020; Tan et al. ²⁰²⁵). Similar interactions can also occur at lipid interfaces. For example, disaccharides can insert between lipid head groups, where their hydroxyl groups form hydrogen bonds that help stabilize lipid‐based structures (Tunsirikongkon et al. 2019). Depending on crystalline organization, amylopectin–lipid complexes can be classified into amorphous Type I and crystalline Type II forms (Luo et al. 2020). These mechanisms are especially relevant to starch‐rich foods, including cereals, baked products, noodles, and plant‐based gels, where lipid inclusion can affect firmness, chewiness, staling, digestibility, and shelf stability.

Polysaccharide‐modified lipid carriers follow a different structural logic. Rather than trapping lipids inside starch helices, polysaccharides decorate, adsorb onto, or become covalently coupled to the surface of lipid droplets, liposomes, or other lipid‐based carriers. This surface modification can improve colloidal stability, reduce aggregation, protect lipids against oxidation, and control the release of lipophilic bioactive compounds. For example, mulberry leaf polysaccharides were covalently attached to liposomes composed of soybean lecithin (SPC), 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine (DSPE), and cholesterol, forming stable caged liposomes with improved lipid‐associated delivery performance (Chen et al. 2025). Although such systems are often studied in delivery models, the underlying principles are directly relevant to food design, particularly for emulsions, fortified beverages, plant‐based meat analogs, and functional foods containing lipophilic nutrients or flavor compounds. Overall, starch–lipid inclusion complexes mainly regulate starch digestibility, retrogradation, and texture, whereas polysaccharide‐modified lipid carriers mainly improve lipid stability, interfacial protection, aroma retention, and delivery efficiency.

2.3. Polysaccharide–Polyphenol Conjugates

During food processing or chewing, cell disruption exposes bound polyphenols to polysaccharides, enabling covalent and non‐covalent complexation (Cortés‐Ferré et al. ²⁰²⁵). Some plant polysaccharide fractions naturally contain high levels of associated polyphenols. For example, Hizikia fusiforme polysaccharides contain 59.43 mg gallic acid equivalents (GAE)/g (J. Li et al. ²⁰²⁵). In fruit juice processing, the lower levels of phenolic acids and proanthocyanidins in juices than in whole fruits reflect the restricted release of polyphenols after binding to cell wall polysaccharides (Liu et al. 2020; Saluk‐Juszczak et al. ²⁰¹⁰). These observations indicate that polysaccharide–polyphenol interactions should be considered determinants of phenolic extractability, sensory expression, and bioaccessibility rather than merely analytical interferences.

At the molecular level, complex formation is governed by multiple interaction sites between polysaccharide hydroxyl, carboxyl, and aldehyde groups and the phenolic hydroxyl groups or aromatic rings of polyphenols. Non‐covalent interactions mainly include hydrogen bonding, hydrophobic association, and electrostatic interactions, whereas covalent linkages may arise from oxidative condensation, radical grafting, esterification, or amidation. The balance among these interactions depends on polysaccharide charge, degree of esterification, branching pattern, and polyphenol structure. For example, pectin enrichment in apple cell walls can reduce the adsorption of negatively charged polyphenols by 129%–311%, probably because of electrostatic repulsion (Liu et al. 2019). The number and position of phenolic hydroxyl groups also affect complex stability, with ortho‐substituted hydroxyls forming more stable complexes than meta‐substituted ones (Fan et al. 2024).

Different polysaccharide–polyphenol systems exhibit distinct binding structures. In starch–polyphenol systems, polyphenols may enter amylose helical cavities and form V‐type inclusion complexes (Yu et al. 2023). In pectin–tannin systems and Asteraceae‐derived conjugates, condensation reactions and ether‐bridged linkages can generate C–O–C/C = C‐containing networks (X. Liu et al. ²⁰²¹). Structural characterization has shown that epigallocatechin gallate (EGCG) complexation can induce crystal collapse and backbone distortion in Dendrobium officinale polysaccharides (DOP) (Peng et al. 2025). These findings indicate that polysaccharide–polyphenol conjugates are not governed by a single binding mechanism, but rather arise from matrix‐dependent combinations of inclusion, adsorption, cross‐linking, and conformational rearrangement.

Functionally, these structural changes influence antioxidant capacity, color stability, astringency, flavor retention, and phenolic release in wines, juices, teas, and plant extracts. By immobilizing phenolics within polysaccharide networks or at polysaccharide‐rich interfaces, these conjugates can protect oxidation‐sensitive compounds (Tsirigotis‐Maniecka et al. ²⁰¹⁹), regulate oral perception, and improve both sensory and health‐related properties (Jakobek et al. 2020). Reversible non‐covalent interactions allow easier release and sensory regulation. In contrast, covalent binding, including oxidation‐mediated binding, provides greater stability but may limit molecular movement and reduce bioaccessibility. Therefore, food design should focus not simply on maximizing binding strength, but on optimizing the balance between phenolic protection, controlled release, sensory quality, and nutritional functionality.

2.4. Polysaccharide–Metal Conjugates

Polysaccharide–metal conjugates, broadly defined here as coordination complexes or mineralized hybrids constructed from food‐relevant polysaccharides and metal ions, are typically generated in water under mild conditions through interactions between metal ions and hydroxyl, carboxyl, amino, or sulfate groups along the polysaccharide backbone (Jing et al. 2020). In these assemblies, metal ions act as coordination nodes, cross‐linking points, or nucleation sites (Lu et al. 2016), while the polysaccharide provides a hydrated ligand shell that limits aggregation and imposes steric and electrostatic stabilization (Zhang et al. 2019). Consequently, their structural integrity is controlled not by a single bond type but by a cooperative network of coordination chelation, electrostatic attraction, and hydrogen bonding, together with ion‐induced chain association in some systems (Ho et al. 2020). These interactions determine particle size, crystallinity, surface charge, chain conformation, and responsiveness to pH, ionic strength, digestive enzymes, and competing ligands in food and gastrointestinal environments (Long et al. 2025).

Representative examples show how polysaccharide composition and metal‐binding mechanisms influence the structure and functional properties of these conjugates. Bletilla striata polysaccharide (BSP) can coordinate with Zn^{2 +} through multiple hydroxyl groups, promoting ZnO nanocore formation and generating a BSP‐wrapped shell structure (Zhang et al. 2020). Licorice polysaccharide forms nanoscale spherical complexes with Ca^{2 +} and Fe^{3 +} through coordination and electrostatic interactions involving abundant polyhydroxy sites, suggesting its potential as a carrier for mineral enrichment and controlled ion delivery (Yang et al. 2024). Lycium barbarum polysaccharide (LBP) coordinates with platinum ions at carboxyl and hydroxyl sites and can reduce platinum ions to Pt(II), forming Pt(II)–LBP conjugates with Pt–O–C and Pt–O–H coordination patterns and enhanced thermal stability (Wang et al. 2020). Platinum‐based conjugates are not typical systems for food fortification, but they provide useful models for studying redox‐active metal binding, metal‐induced structural changes, and polysaccharide‐mediated stabilization (Raju et al. 2020).

Platinum‐based conjugates are not typical systems for food fortification, but they provide useful models for studying redox‐active metal binding, metal‐induced structural changes, and polysaccharide‐mediated stabilization. However, their food application requires careful control of metal speciation and ion release under gastrointestinal conditions, coordination stability, sensory effects, and potential pro‐oxidant activity in real matrices. Key formulation variables include competition with proteins, polyphenols, phytates, salts, and other food‐matrix components, as well as effects on color, flavor, texture, processing tolerance, and storage stability.

2.5. Polysaccharide–Other Molecular Conjugates

Polysaccharides can also interact with flavonoids, anthocyanins, alkaloids, terpenoids, lignin‐related units, and flavor molecules (Mundlia et al. 2019). These compounds differ greatly in polarity, charge, aromaticity, reactivity, volatility, molecular structure, and oxidation sensitivity (Ma et al. 2022). Therefore, their conjugates should be treated as separate mechanistic groups rather than as a single category (Szejk et al. 2017). This distinction is particularly important for food systems, where the same polysaccharide matrix may simultaneously affect phytochemical stability, aroma release, texture, and gastrointestinal behavior.

Small phenolic molecules, including flavonoids and anthocyanins (Alejandra et al. 2019), mainly bind to polysaccharides through hydrogen bonding, hydrophobic interactions, aromatic stacking, and electrostatic effects when charged groups are present (Kolodziejczyk‐Czepas et al. ²⁰¹⁵). In some cases, oxidative, thermal, or acid‐induced reactions can further generate covalent linkages. For example, during apple sauce production, thermal processing and acidic conditions may promote deprotonation of cyanidin‐3‐glucoside and the formation of a carbocation, allowing covalent bonding with nucleophilic groups on polysaccharides (Le Bourvellec et al. 2019). These interactions can improve thermal stability and antioxidant retention.

Hydrophobic or weakly polar molecules, such as alkaloids and terpenoids, are more commonly associated with polysaccharides through hydrophobic effects, van der Waals interactions, inclusion behavior, and electrostatic attraction. For alkaloids, association with negatively charged polysaccharide groups may improve dispersion and apparent bioavailability by reducing aggregation, moderating release, and protecting labile compounds during digestion. For terpenoids, amylose helices can provide hydrophobic cavities that support V‐type inclusion complex formation, with enhanced thermal stability and antioxidant function (Zuo et al. 2023). Such inclusion or carrier‐like behavior is relevant to food formulation because many terpenoids are poorly water‐soluble, volatile, and chemically unstable during heating, storage, or gastrointestinal exposure.

Lignin‐related units and flavor molecules further expand the functional roles of polysaccharide conjugates. Phenylpropanoid and lignin‐derived units can form ester, ether, or aromatic cross‐linked structures with polysaccharide hydroxyl or carboxyl groups, generating rigid networks with improved thermal resistance and antioxidant stability as well as potential improvements in mechanical strength and water‐holding behavior (Xiao et al. 2025). Flavor molecules such as aldehydes, alcohols, and esters can bind to amylose through hydrogen bonding and hydrophobic interactions (Mundlia et al. 2021), thereby modulating solubility, gelatinization, retrogradation, aroma retention, palatability, and texture (Tu et al. 2023). In addition, ferulic acid–arabinogalactan cross‐linking can inhibit radish softening during heating, highlighting the potential of polysaccharide–small molecule conjugates in texture regulation (Ho et al. 2020).

2.6. Polysaccharide Multivalent Conjugates

Compared with binary conjugates, multicomponent polysaccharide systems show greater structural complexity because polysaccharides can co‐assemble with proteins, polyphenols, metals, and small molecules through electrostatic interactions, hydrogen bonding, hydrophobic forces, and covalent linkages (Yan et al. 2020). Their structures are governed by component ratio, pH, ionic strength, heat treatment, and order of addition (Wu et al. 2021), which determine whether stable complexes, coacervates, gels, or aggregates are formed.

Representative protein–polysaccharide–polyphenol systems illustrate this behavior. In soy protein isolate(SPI)–citrus pectin–gallic acid conjugates, citrus pectin regulates protein–polyphenol binding and promotes an ordered three‐dimensional network (Koshani et al. 2015), thereby improving solubility, interfacial properties, and antioxidant performance (Xu et al. 2023). In SPI–beta‐glucan–myricetin (MC) conjugates, protein interfacial stabilization, polysaccharide steric protection, and polyphenol‐mediated reinforcement jointly strengthen the network through hydrogen bonding, pi–pi stacking, and covalent interactions (Jian et al. 2023). Similarly, phenolic compounds such as quercetin, EGCG, and caffeic acid can strengthen protein–polysaccharide binding (Jiang et al. 2025). The β‐lactoglobulin (BLG)–arabic gum–quercetin system further illustrates this multistep assembly process. Complex formation first proceeds through exothermic electrostatic interactions and hydrogen bonding, followed by an entropy‐driven stage involving ion and water release, hydrophobic interactions, reduced β‐sheet content, and stabilization of the protein–polysaccharide–flavonoid complex (Aberkane et al. 2012). Other protein–sugar–phenol networks, such as those in Lysimachia chinensis alkali extract, show enhanced C = O and C–O–C signals that correlate with bronchodilatory activity in animal models (Elkhawas et al. 2024).

From a food science perspective, these multicomponent systems are more similar to real plant‐based foods than simple two‐component conjugates. They may improve thickening, emulsification, color and flavor stability, antioxidant protection, and controlled release. However, these benefits must be confirmed in actual food products during processing, storage, digestion, and sensory evaluation. The classification, structural features, binding mechanisms, and functional improvements of representative PPCs are summarized in Table 1.

TABLE 1.

Classification and structural features.

Type	Polysaccharide source	Macromolecules	Binding mechanism	Average molecular weight (kDa)	Functional improvements	Reference
Protein/peptide	Tragacanthin	Lysozyme	Maillard reaction	——	Enhanced solubility, emulsification, and antibacterial activity	Koshani et al. (2015)
	Lycium barbarum	Whey protein isolate	Hydrogen bonding and electrostatic interaction	——	Improved antioxidant and stability under stress	Al Wraikat et al. (2024)
	Ganoderma lucidum	Soy protein	Hydrophobic interaction and H‐bonding	——	Better gelation and functional food compatibility	Koshani et al. (2015)
	Astragalus	Ovalbumin	Electrostatic complexation	——	Increased immunogenicity and delivery efficiency	Koshani et al. (2015)
	Abelmoschus esculentus (okra)	Lactoferrin	Maillard‐type covalent conjugation and steric hindrance	——	Inhibits thermal aggregation at neutral pH, enhances protein stability and solubility	Jiang et al. (2025)
	Rosa rugosa Thunb.	Peptides	Covalent and non‐covalent interaction via glycosylation and peptide grafting	180 kDa	Antioxidant capacity, structural integrity	Olech et al. (2023)
Lipid	Mulberry leaf	Soy lecithin (SPC), DSPE, and cholesterol	Covalent modification—amphiphilic assembly	——	Enhanced gastrointestinal stability, controlled release, improved lymphatic absorption	Chen et al. (2025)
	Phragmites communis	Lipids in aerial part, roots, and inflorescences	Electrostatic interaction	——	Cytotoxic activity against HeLa cells	Yuldasheva et al. (2021)
Polyphenol	Oat β‐glucan	Tea polyphenols	Hydrogen bonding, hydrophobic interaction	230 kDa	Antioxidant capacity, thermal stability	Jakobek et al. (2020)
	Agrimonia eupatoria L.	Polyphenols (lignin‐related units, dimethoxyphenyl structures)	Covalent and non‐covalent interactions	55 kDa	Anticoagulant activity	Tsirigotis‐Maniecka et al. (2019)
	Pectin polysaccharides (from fruits)	Anthocyanins	Non‐covalent hydrogen bonding, hydrophobic interaction; π–π stacking; insertion into polysaccharide domains	200–250 kDa	Enhanced color stability, improved antioxidant activity, increased thermal and pH tolerance of anthocyanins	Wang et al. (2020)
	Pectin	Naringenin (flavonoid)	Non‐covalent interactions (hydrogen bonding, hydrophobic forces, π–π stacking)	218 kDa	Antioxidant activity, antibacterial, anticancer	Mundlia et al. (2019)
	Corn starch	Ferulic acid	N,N′‐carbonyldiimidazole (CDI)‐mediated esterification (covalent grafting)	——	Antioxidant activity, enhanced free radical scavenging and structural stability	Wen et al. (2016)
	Gum arabic	Ferulic acid	Covalent grafting (CDI‐mediated ester/amide linkages) and non‐covalent interactions	——	Antioxidant, thermal stability	Vuillemin et al. (2020)
	Gellan gum	Curcumin, naringenin	Hydrogen bonding and hydrophobic interaction	——	Antioxidant, antibacterial, bioactive stability	Mundlia et al. (2021)
	Asteraceae medicinal plants	Phenolic acids	Hydrogen bonding, possible Schiff base formation, oxidative crosslinking	——	Platelet protection, antioxidant, cardiovascular support	Saluk‐Juszczak et al. (2010)
	Crataegus pinnatifida	Polyphenols	Hydrogen bonding, hydrophobic interaction, partial covalent conjugation	——	Protected platelet proteins, cardiovascular protective	Pawlaczyk‐Graja et al. (2019)
	Apple cell walls	Epicatechin, phloridzin, chlorogenic acid, procyanidin	Hydrophobic interaction, hydrogen bond	——	Anti‐inflammatory	Liu et al. (2019)
	Blueberry pectin	Anthocyanins	Electrostatic interaction, hydrophobic interaction, hydrogen bond	——	Antioxidant	Alejandra et al. (2019)
Metal	Licorice	Ca2 +/Fe3 +	Metal bridging via hydroxyl‐rich chain domains	——	Sustained release	Yang et al. (2024)
	Fritillaria ussuriensis Maxim	Zn2 +	Coordination bonding and electrostatic interaction	——	Improved Zn bioavailability	Zhang et al. (2020)
	Glehniae Radix	Fe3 +	Carboxyl/hydroxyl coordination, O–Fe–O chelation ring	——	Antioxidant activity, improved Fe bioavailability and stability	Jing et al. (2020)
	Garlic	Cr (III)	Coordination via hydroxyl (O–H) and C–O/O–C–O structures	9.24 kDa	α‐Glucosidase inhibition, hypoglycemic activity	Song et al. (2023)
	Momordica charantia L.	Cr (III)	Coordination bonding (O–H and C–O groups)	——	Improved insulin secretion	Zhang et al. (2019)
	Astragalus membranaceus	Fe (III)	Coordination via hydroxyl and carboxyl groups forming O–Fe–O chelate rings	51.8 kDa	Antioxidant activity, improved gastrointestinal release	Lu et al. (2016)
	Lycium barbarum	Platinum (Pt)	Redox‐assisted coordination via –COOH/OH groups	——	Targeted drug delivery, enhanced antitumor activity	Wang et al. (2020)
	Dendrobium officinale	Selenium nanoparticles (SeNPs)	Electrostatic interaction, hydrogen bonding, hydroxyl stabilization	——	Improved selenium stability, immunomodulatory effect	Long et al. (2025)
Small molecule	Pseuderanthemum palatiferum	Natural polyphenols (multi‐caffeic‐type)	Covalent bonding via etherification (C–O–C) and condensation	——	Anticoagulant activity, structural stability	Ho et al. (2020)
	Matricaria chamomilla L.	Polyphenols	Covalent etherification and esterification (C–O–C/C = O)	——	Antioxidant capacity, improved free radical scavenging	Kolodziejczyk‐Czepas et al. (2015)
	Rosaceae/Asteraceae family	Polyphenol glycosides	Native glycosidic conjugation and coexistent complexation	——	DNA protection from radiation, ROS inhibition, antiapoptotic effect	Szejk et al. (2017)
	Jujube	Cyclic adenosine monophosphate (cAMP)	Weak hydrogen bonding, electrostatic interaction, and hydrophobic association	——	Improved intestinal absorption and prolonged bioavailability	Ma et al. (2022)
	Agrimonia eupatoria L.	Polyphenol glycosides	Native glycosidic conjugation	——	ROS scavenging, NF‐κB inhibition, anti‐inflammatory activity	Tsirigotis‐Maniecka et al. (2023)
	Punica granatum	Cysteine	Reductive amination (covalent) and –SH	——	Anticancer and antimetastatic	Raju et al. (2020)
Multivalent conjugates	Dextran (DEX)	Bovine serum albumin (BSA)	Covalent bonding via Maillard reaction	51.8 kDa	Enhanced emulsion stability, bioaccessibility of lutein	Yan et al. (2020)
	β‐Glucan	Soy protein isolate (SPI) + myricetin (MC)	H‐bonding, electrostatic, π–π stacking	——	Antioxidant protection, better β‐carotene delivery	Jian et al. (2023)
	Hovenia dulcis	Polyphenolic–protein–polysaccharide	C = C stretching vibrations	59.7 kDa	Antiglycation activity	Wu et al. (2021)
	Quercetin	Acacia gum–β‐lactoglobulin	Electrostatic and hydrophobic interactions	18 kDa	Structural stability	Aberkane et al. (2012)

3. Extraction, Synthesis, and Process Optimization

3.1. Natural Conjugate Extraction

Natural PPCs may form within plants or during food processing. PPCs formed in plants should be extracted under mild conditions to preserve their native structures, whereas process‐induced PPCs require controlled processing to ensure consistent formation and properties.

For preexisting PPCs, extraction aims to release conjugates from cell wall or storage matrices while limiting depolymerization, oxidation, and loss of bound phenolics. Conventional methods, including hot water extraction (HWE) and alkaline reflux, remain widely used because of their simplicity (Figure 2). However, these approaches may have low extraction efficiency, high solvent consumption, and potential degradation of heat‐sensitive constituents. Thus, improved protocols usually combine extraction with selective enrichment. For example, HWE coupled with solid‐phase extraction (SPE) yielded pectin‐rich polyphenol–polysaccharide complexes with anticoagulant activity and internal networks of pectic polysaccharides, polyphenols, and uronic acids (Wu et al. 2020). Extraction methods may need to be adjusted to the plant source. For example, conjugates from Asteraceae and Rosaceae plants may require delipidation, alkaline extraction of cell wall‐bound fractions, methanol precipitation, and dialysis to enrich the macromolecular conjugates (Xue et al. 2025). Enzyme‐assisted alkaline extraction followed by diethylaminoethyl–Sepharose purification has similarly been used to obtain PPCs from Hizikia fusiforme (S. Li et al. ²⁰²⁵).

FIGURE 2.

Extraction, synthesis, and process optimization of plant‐derived polysaccharide conjugates.

In contrast, some PPCs are formed or substantially modified during processing rather than simply extracted from raw materials. Moist‐heat treatments, such as steaming, boiling, and stewing, can partially depolymerize polysaccharides and promote their self‐assembly with phenolics or proteins through hydrogen bonding, electrostatic attraction, and hydrophobic interactions. In Polygonatum sibiricum, steaming and boiling altered monosaccharide composition and produced more stable bioactive conjugates (Li et al. 2021). Chemical complexation can also introduce metal ions into polysaccharide matrices, producing polysaccharide–metal conjugates with distinct functional properties. Therefore, food processing can both release existing conjugates and promote the formation of new ones.

Recent green extraction technologies have been introduced to improve recovery while preserving conjugate activity. These include ultrasound‐assisted extraction, enzyme‐assisted extraction, pressurized liquid extraction (PLE), supercritical fluid extraction (SFE), microwave‐assisted extraction (MAE), ultrasound–microwave combined extraction (UMAE), and high‐shear homogenization extraction (HSHE). Ultrasound‐assisted extraction is especially effective because cavitation improves mass transfer. When properly controlled, it can also help preserve polysaccharide molecular weight and bound phenolic compounds.

Despite these advances, PPC extraction remains challenging because many conjugates occur at low abundance or in tightly bound forms. Harsh conditions may degrade sensitive components, whereas mild conditions may give insufficient yield. Therefore, future extraction strategies should balance efficiency, structural preservation, scalability, and sustainability and should be optimized not only for yield but also for molecular weight distribution, phenolic retention, conjugate stability, bioactivity, sensory quality, and compatibility with food‐grade processing to maximize recovery while maintaining the nutritional and sensory properties of PPCs (Pawlaczyk‐Graja et al. ²⁰¹⁹).

3.2. Processing‐Induced Synthesis

Processing can also be used to produce polysaccharide conjugates with desired structures and functions. Food‐compatible routes include physical assembly, ionic cross‐linking, and enzyme‐mediated conjugation, whereas chemical cross‐linking and some nanotechnology‐assisted methods require stricter safety and regulatory evaluation. Physical assembly relies mainly on non‐covalent interactions and is therefore the most practical route for food applications. Anti‐solvent precipitation, adsorption‐driven self‐assembly, and controlled gelation can form nanoparticles or co‐precipitates through hydrogen bonding, electrostatic attraction, hydrophobic interactions, and pH‐ or ion‐induced network formation (D.‐H. Lee et al. ²⁰²⁵).

Covalent approaches provide stronger conjugates but are more constrained by reagent safety. Maillard‐type glycation and enzyme‐mediated reactions using laccase or transglutaminase are relatively promising for food use, whereas glutaraldehyde‐, quinone‐, carbodiimide‐, or radical‐mediated reactions are mainly useful for mechanistic or material‐design studies unless food‐grade conditions are established (Wu et al. 2023). Ionic cross‐linking offers a milder alternative in which Ca^{2 +}, Mg^{2 +}, or Fe^{3 +} bridges negatively charged polysaccharides, proteins, or bioactives to improve network cohesion and encapsulation efficiency (Cao et al. 2025).

External energy–assisted processes, including ultrasonication, microwave heating, ultrasound–microwave treatment, high‐shear homogenization, and pulsed electric fields, can accelerate conjugate formation, improve dispersion, and reduce processing time (Zhang et al. 2023). Similar process‐controlled strategies have been applied to polysaccharide–metal complexes, such as co‐heating polysaccharide extracts with iron (III) salts or using biomimetic mineralization to obtain uniform polysaccharide–metal conjugates (Dai et al. 2024). Polysaccharides can also guide the formation of nanomaterials and act as stabilizers during green synthesis. However, their safety and suitability must be carefully evaluated before use in foods.

For food applications, physical assembly, ionic cross‐linking, and enzyme‐mediated conjugation are generally more practical. Chemical cross‐linking and some nanotechnology‐based methods offer better control over structure, but their safety, regulatory acceptance, and large‐scale production require further evaluation.

3.3. Reaction Mechanism Regulation and Process Optimization

The structure and properties of polysaccharide conjugates depend on both molecular characteristics and processing conditions. Important molecular factors include chain composition, molecular weight, branching, and acidic group content. Processing factors include pH, temperature, ionic strength, solvent polarity, and component ratio. In most systems, optimization mainly involves controlling molecular charge, exposing more binding sites, and improving network stability (Al Wraikat et al. 2024).

Molecular charge affects the attraction and repulsion between components, which in turn influences conjugate formation, dispersion stability, and molecular assembly. pH adjustment, phenolic oxidation, enzyme catalysis, and component‐ratio control can shift zeta potential and interfacial charge distribution, promoting non‐covalent complexation or covalent coupling. Electrostatic interactions often dominate under acidic conditions, whereas hydrogen bonding and hydrophobic association may become more important when electrostatic attraction weakens, indicating that conjugate formation is usually governed by coupled interactions rather than a single force.

Exposing more binding sites allows polysaccharides and other components to interact more easily. Physical treatments such as ultrasonication, heating, high‐pressure processing, and drying can modify crystalline and amorphous regions, expose hydrophobic domains, and improve dispersion stability. Similarly, pressurized water extraction (PWE) and HWE can increase polyphenol content and antioxidant capacity by exposing hydroxyl, carboxyl, hydrophobic, and other functional domains that participate in conjugate formation.

Network stabilization is essential for maintaining conjugate integrity during processing, storage, and gastrointestinal exposure. Stability can be enhanced through covalent reinforcement, dynamic cross‐linking, amphiphilic design, or chemical modification such as phosphorylation, carboxymethylation, selenylation, and sulfhydration. For example, polyethylene glycol‐modified Rehmannia glutinosa polysaccharide forms nanoadjuvant particles whose size, zeta potential, loading efficiency, stability, and release behavior depend on mass ratio and reaction conditions (Huang et al. 2019). Similarly, stearic acid‐modified BSP forms a hydrophobic‐core/hydrophilic‐shell structure that supports particle‐size control and sustained release (Zhang et al. 2023). Overall, optimization should balance molecular charge, binding‐site availability, and network stability to improve function and resistance to environmental changes.

4. Mechanisms in Regulating Sensory Characteristics

4.1. Color Regulation

Color is a key sensory attribute in functional foods and traditionally processed products. In PPCs‐containing foods, it is governed by three related processes: pigment formation, pigment stabilization, and processing control. During thermal processing, reducing sugars and polysaccharide degradation products react with amino groups through the Maillard reaction (Yang et al. 2015), generating 5‐hydroxymethylfurfural (5‐HMF) and brown melanoidins (Figure 3A). This pathway contributes to color darkening and flavor development in processed Polygonatum, Panax ginseng, and Polygonum multiflorum (Jiang et al. 2022). Repeated steaming and sun‐drying of Polygonum multiflorum promote polysaccharide degradation and glycoprotein formation, whereas ginseng steaming produces a reddish‐black surface and roasted aroma through reactions between polysaccharide‐derived carbonyls and amino groups (Idoudi et al. 2024; Qiu et al. ²⁰²⁴).

FIGURE 3.

The regulatory mechanism of sensory characteristics.

PPCs can also stabilize preexisting pigments by limiting degradation, bleaching, or structural conversion during storage and processing. Polysaccharides protect natural colorants through hydrogen bonding, electrostatic attraction, hydrophobic association, and physical encapsulation. In anthocyanin‐rich systems, pectic polysaccharides from grape skins bind malvidin‐3‐O‐glucoside through hydrophobic interactions, thereby improving thermal stability and color intensity (Fernandes et al. 2021). These interactions can also reduce the hydration of the flavylium cation and preserve red hues under mildly acidic conditions. Similar stabilizing effects have been reported for Aronia melanocarpa polysaccharide–anthocyanin complexes formed through hydrogen bonding and cation–pi interactions (H. Zhang et al. ²⁰²⁵). In fermented beverages, high‐molecular‐weight tannins can co‐assemble with polysaccharides and anthocyanins to form copigmentation complexes that support long‐term color stability (Gonzalo et al. 2022). Polysaccharides can also protect chlorophyll from degradation. For example, xanthan gum and sodium alginate improve its stability during heating and changes in pH (Jin et al. 2024).

Processing conditions further determine whether PPC formation promotes browning or preserves desirable pigments. Modern techniques can be used to guide this balance. Ultrasound‐assisted glycosylation, for example, accelerates the conjugation of peanut protein with polysaccharides and produces products with higher brightness and lower yellowness than conventional heat‐treated controls (F. Wang et al. ²⁰²⁵). Thus, controlling pH, temperature, treatment time, and energy input can minimize undesirable browning while improving pigment stability in food systems.

4.2. Aroma Regulation

PPCs influence aroma by retaining volatile compounds, promoting aroma formation, and controlling aroma release. Polysaccharides can retain aldehydes, ketones, terpenes, and other volatile compounds through hydrogen bonding, hydrophobic interactions, and physical entrapment. For example, gum arabic forms protective films around flavor‐oil droplets (Vuillemin et al. 2020), while freeze‐dried carbohydrate matrices help reduce volatile loss during storage (Figure 3B).

During thermal processing, polysaccharide‐derived carbonyl compounds react with amino groups through Maillard pathways to generate aroma‐active pyrazines and furans with roasted and nutty notes. Protein–polysaccharide association may further expose hydrophobic binding sites that retain volatiles. In contrast, low‐molecular‐weight reducing sugars contribute more readily to aroma formation than larger polysaccharides, such as maltodextrin, because steric constraints reduce the latter's reactivity (Huang et al. 2023).

PPC networks also control aroma release by regulating volatile accessibility and diffusion. Amylose helices can include aroma molecules within their hydrophobic cavities and release them as the starch matrix disintegrates (Chen et al. 2023). Similarly, polysaccharide–protein adducts formed during tea processing can stabilize key aroma compounds through complexation and encapsulation (Xu et al. 2025). Through these physical, chemical, and microenvironmental interactions, PPCs contribute to richer and longer‐lasting aroma profiles in foods and beverages.

4.3. Taste Regulation

PPCs regulate taste mainly by reducing bitterness and astringency through electrostatic capture, polyphenol sequestration, steric shielding, and diffusion control. Many bitter alkaloids and peptides are positively charged at oral pH and can associate with anionic polysaccharides, thereby reducing their access to bitter‐taste receptors (Figure 3C). For example, citrus pectin–potato protein complexes increased the negative surface charge of the system and reduced perceived bitterness by binding cationic bitter compounds (Huang et al. 2025).

Polysaccharides can reduce astringency by binding polyphenols and preventing tannins from interacting with salivary proteins. For example, pectin and gum arabic can bind polyphenols or block tannin‐binding sites, thereby reducing tannin–protein precipitation and the associated dry or puckering mouthfeel (Cheng et al. 2025; Gonzalo et al. ²⁰²²; Manjón et al. ²⁰²³). Highly branched and flexible polysaccharide chains may also provide spatial domains that retain hydrophobic flavor compounds, as supported by nuclear magnetic resonance (NMR) analysis (Liu et al. 2025).

In addition to molecular binding, viscous or gel‐like PPC networks can physically limit taste‐compound diffusion. An SPI–pectin co‐gel, for instance, encapsulated bitter peptides and reduced the bitterness of casein hydrolysate (Tian et al. 2025). Through electrostatic interactions, polyphenol binding, steric shielding, and diffusion control, PPCs can reduce bitterness and astringency, providing a food‐compatible approach to taste modulation without the need for synthetic masking agents.

4.4. Texture Regulation

PPCs regulate texture through network formation, processing‐induced restructuring, and formulation‐driven assembly. Their gel and three‐dimensional networks influence softness, smoothness, elasticity, chewiness, and water retention (Pawde and Dave 2025). During processing, polysaccharide hydrolysis and molecular reorganization alter interactions with proteins and phenolics, thereby changing network density and continuity (Figure 3D). In steamed Polygonatum, shorter polysaccharide fragments interact with released phenolics, promoting gelation and product softening (Zhang et al. 2024). Processing conditions further tune these networks. Temperature, pH, and shear can disrupt or reorganize hydrogen bonding and other non‐covalent interactions, leading to transitions in texture from firmer to softer states (Al‐Akayleh et al. ²⁰²⁵). Deliberate conjugation provides an additional strategy for texture control (Ding et al. 2025). Under laccase catalysis, pea protein and beet pectin form a cross‐linked gel network with improved binding strength and elasticity (Wei et al. 2020), outperforming methylcellulose as a texture builder (Moll et al. 2023).

In formulated foods, passion fruit polysaccharides interact with casein micelles via carboxyl–amino electrostatic interactions, thereby strengthening yogurt gels, improving water‐holding capacity, and producing a smoother texture (Yu et al. 2025). Sodium caseinate–locust bean gum systems likewise increase viscosity, firmness, foam stability, and resistance to syneresis in low‐fat cream (Rezvani et al. 2020). Ferulic acid‐mediated AX cross‐linking also helps retain the firmness of vegetables during heating (Li et al. 2019). Overall, PPC‐based texture design should balance network strength, moisture retention, and oral breakdown to improve product stability and consumer acceptance.

5. Bioactivity and Mechanism of PPCs

5.1. Regulation of Gut Microbiota

PPCs can influence the gut microbiota by delivering fermentable polysaccharides and polyphenols to the colon. These compounds may promote the growth of beneficial bacteria, suppress harmful microbes, and increase the production of short‐chain fatty acids (SCFAs), helping to maintain gut health. During gastrointestinal transit, PPCs undergo swelling, debranching, partial hydrolysis, and microbial enzyme‐mediated degradation. This gradual transformation releases oligosaccharides and phenolic metabolites that alter substrate availability and microbial composition. For example, polyphenols bound to LBP are minimally released during upper gastrointestinal digestion, but are extensively liberated and metabolized during colonic fermentation. This process is accompanied by increased abundances of Bacteroides, Parabacteroides, and Clostridioides (Liang et al. 2024). Similar effects have been reported for conjugates from Hippophae rhamnoides L., Hizikia fusiforme (X. Wang et al. ²⁰²⁵), and Grifola frondosa, which increased SCFA production, enriched beneficial bacteria, and improved microbial metabolic balance (Guo et al. 2020; Long et al. ²⁰²⁵). Black tea polysaccharide conjugates also promoted intestinal barrier repair by modulating Toll‐like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa B (NF‐κB) and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling. These changes were accompanied by increased expression of immune defense factors and tight junction proteins (Liu et al. 2026; L. Zhang et al. ²⁰²⁵).

Importantly, these effects depend on the binding state of the phenolic components. During apple processing, cell wall‐bound proanthocyanidins restricted microbial degradation, whereas free proanthocyanidins reduced SCFA production, including butyrate, and altered metabolic processes associated with taxa in the phylum Actinobacteria (Liang et al. 2025). Therefore, PPCs not only provide fermentable substrates for gut microbes but also help regulate microbial composition, SCFA production, and intestinal homeostasis.

5.2. Immune Modulation

The immunomodulatory activity of PPCs is influenced by their structural features, surface charge, and the multivalent display of sugar residues. These structural features determine recognition by innate immune receptors, including Toll‐like receptor 2 (TLR2), TLR4, and dectin‐1, and promote receptor clustering and signal amplification. After ligand binding, NF‐κB and mitogen‐activated protein kinase (MAPK) signaling pathways can be activated, leading to macrophage and natural killer (NK) cell activation and the secretion of immune effector molecules such as interleukin‐2 (IL‐2), interferon‐γ (IFN‐γ), and nitric oxide (Dai et al. 2018; Wang et al. ²⁰²⁴)

Structural remodeling during digestion and colonic fermentation may further shape immune activity. Partial depolymerization and debranching may expose structural features associated with immune recognition, whereas microbial degradation releases oligosaccharides and phenolic metabolites that may contribute to antigen presentation, T‐cell activation, and Th1/Th2 immune balance (Jia et al. 2024). Representative systems demonstrate these complementary mechanisms. Ophiopogon‐derived polysaccharide–polyphenol–protein conjugates strengthened the mucosal barrier while suppressing TLR/NF‐κB signaling, and tea polysaccharide conjugates reduced autoimmune injury in diabetic mice. Soy protein–polysaccharide conjugation also reduced immunoglobulin E (IgE)‐binding potential by modifying allergenic epitopes (Liu et al. 2024; Qiu et al. ²⁰²⁵; Šutovská et al. ²⁰²²). Overall, PPCs may exert immunomodulatory effects through receptor‐mediated signaling, digestive and microbial transformation, and regulation of adaptive immune responses.

5.3. Antioxidant and Anti‐Inflammatory

PPCs exert antioxidant and anti‐inflammatory effects through electron donation, radical scavenging, metal chelation, and structural stabilization (Figure 4). Hydroxyl, carboxyl, and aromatic groups in polysaccharide–polyphenol systems can quench radicals and interrupt oxidative chain reactions (Vuillemin et al. 2020). For example, Agrimonia eupatoria polyphenol–polysaccharide conjugates enhanced radical‐scavenging activity and reduced interleukin‐6 (IL‐6) and tumor necrosis factor‐alpha (TNF‐α), whereas lotus root polysaccharide–phenol complexes showed improved anti‐inflammatory activity following hydrogen bond–mediated structural reorganization (Peng et al. 2023; Tsirigotis‐Maniecka et al. ²⁰²³).

FIGURE 4.

Bioactivity and mechanism of plant polysaccharide conjugates.

Metal coordination and covalent anchoring provide additional pathways for enhancing antioxidant and anti‐inflammatory activities. Metal‐coordinated conjugates containing Zn^{2 +} or Fe^{3 +} can improve redox‐buffering capacity, promote reactive oxygen species (ROS) decomposition, block MAPK cascades, and downregulate inflammatory mediators, as reported for polysaccharide–Zn^{2 +} systems from Flammulina velutipes, Fritillaria ussuriensis, corn silk, and ginger peel (Jia et al. 2021; Li et al. ²⁰²²; Qiu et al. ²⁰²⁴). Meanwhile, Maillard‐type protein–polysaccharide conjugates release electron‐rich amino acid residues that help terminate radical chain reactions, and ultrasound‐assisted covalent coupling can further enhance antioxidant capacity (Zheng et al. 2024). The binding mode is therefore an important determinant of activity (Wen et al. 2016). A covalent DOP–epigallocatechin gallate (EGCG) conjugate showed greater thermal stability and radical‐scavenging activity than its non‐covalent counterpart (Peng et al. 2025). Nevertheless, these benefits should be validated in real food matrices and in vivo models because processing, digestion, and competing food components may alter antioxidant performance.

5.4. Blood Sugar Regulation and Lipid Homeostasis

Natural PPCs may support blood glucose and lipid homeostasis by improving gastrointestinal stability, inhibiting digestive enzymes, and modulating metabolic signaling. Inhibition of α‐glucosidase and α‐amylase can slow starch hydrolysis and glucose release. Auricularia cornea Ehrenb. polysaccharide–zinc conjugates increased digestive‐enzyme inhibition and reduced oxidative stress in insulin‐resistant HepG2 cells. Grape pomace polyphenol–polysaccharide complexes also inhibited α‐amylase, reduced glucose transport, and showed stronger α‐glucosidase inhibition and antiglycation activity after oxidation (Fan et al. 2024; T. Liu et al. ²⁰²¹; Zhu et al. ²⁰²⁵).

Metal‐coordinated systems, particularly chromium (III) (Cr (III))–polysaccharide conjugates, have shown broader metabolic effects in preclinical models. Pumpkin peel polysaccharide–Cr (III) conjugates promoted glucose utilization through the AMP‐activated protein kinase (AMPK)/glycogen synthase kinase‐3 beta (GSK‐3β) pathway (Zhang et al. 2022), while garlic and Momordica charantia L. conjugates improve insulin resistance and inhibit digestive enzymes (Song et al. 2023).

Grifola frondosa polysaccharide–Cr(III) further regulates both glucose and lipid metabolism by suppressing gluconeogenesis, promoting glycogen synthesis, reducing lipogenesis, and enhancing fatty acid β‐oxidation through phosphoinositide 3‐kinase (PI3K)/protein kinase B (Akt) and lipid metabolism‐related pathways (Guo et al. 2020). Tea polysaccharide conjugates, which are enriched in summer and autumn teas, also improve glucose tolerance and delay the progression from impaired glucose tolerance to diabetes (Erukainure et al. 2025). Collectively, these findings support the potential of PPCs for managing postprandial glycemia and dyslipidemia, but confirmation in well‐controlled human studies remains necessary.

5.5. Antitumor Activity

Natural PPCs have shown antitumor potential in preclinical studies through targeted delivery, induction of apoptosis, regulation of signaling, immune activation, and remodeling of the tumor microenvironment. An Auricularia auricula‐judae polysaccharide–cisplatin conjugate was reported to enhance folate receptor–mediated cisplatin uptake, increase apoptosis, and reduce toxicity (Kim et al. 2025). Sulfation of Portulaca oleracea polysaccharides also increased cytotoxicity across several tumor cell lines (Han et al. 2021).

PPCs also regulate tumor‐related signaling and immune responses. Bullacta exarata polysaccharide conjugates inhibit hepatocellular carcinoma proliferation by upregulating p53, p21, and Bax while suppressing Bcl‐2 (Kim et al. 2025). High‐molecular‐weight oolong tea polysaccharide–polyphenol conjugates inhibit cell‐cycle progression and suppress invasion‐ and metastasis‐associated factors such as matrix metalloproteinase‐2 (MMP‐2) and matrix metalloproteinase‐9 (MMP‐9) (Rashwan et al. 2025). Immune‐mediated mechanisms may further contribute. LBP–protein conjugates inhibited tumor growth while increasing macrophage phagocytosis, lymphocyte proliferation, cytotoxic T‐cell activity, and IL‐2 expression (Mandal et al. 2025). Grifola frondosa polysaccharide–protein conjugates may also suppress colorectal cancer progression by modulating lipid metabolism in the tumor microenvironment (He et al. 2023). However, current evidence is largely derived from cell and animal studies, and further research is needed to evaluate pharmacokinetics, tumor selectivity, long‐term safety, and clinical efficacy.

5.6. Other Activities

PPCs have also shown anticoagulant, antitussive, radioprotective, and antibacterial activities in preclinical studies. These findings further illustrate how conjugation may alter biological activity relative to the individual components, although the available evidence remains largely limited to in vitro and animal models. Polyphenol–polysaccharide conjugates from Asteraceae and Rosaceae families, Echinacea purpurea (L.) Moench, Fragaria vesca L., and Rubus plicatus W. Et N., show significant anticoagulant activity in vitro (Barragan‐Galvez et al. ²⁰²⁴; H. J. Lee et al. ²⁰²⁵; Li et al. ²⁰²⁴). This effect has been associated with flavonoid‐rich polyphenolic moieties and galacturonic acid‐rich polysaccharide chains with low degrees of esterification. Hawthorn flower conjugates preferentially inhibited factor Xa through antithrombin, whereas fruit‐derived fractions mainly inhibited thrombin through heparin cofactor II, indicating source‐dependent anticoagulant mechanisms (Marchelak et al. 2023).

In addition to the activities discussed above, some PPCs have demonstrated antitussive and radioprotective effects. Lythrum salicaria polysaccharide–polyphenol conjugates reduce citric acid‐induced cough frequency and airway resistance, with efficacy comparable to low‐to‐moderate doses of salbutamol (Martina et al. 2025). Polyphenol–polysaccharide conjugates from Sanguisorba officinalis L., Erigeron canadensis L., F. vesca L., and blackberry leaves mitigate γ‐radiation‐induced lipid peroxidation in human plasma and DNA damage in lymphocytes (Untea et al. 2024). Antibacterial activity has also been reported for Bi^{3 +}‐complexed Hericium erinaceus polysaccharides, which exhibited inhibitory effects against Helicobacter pylori comparable to those of colloidal bismuth subcitrate, with a minimum inhibitory concentration (MIC) of 20 µg/mL (Ni et al. 2025). Overall, these findings broaden the potential applications of PPCs, but their effective doses, safety, bioavailability, and performance in food matrices and human studies require further validation.

6. Applications of Conjugates in Functional Foods and Nutrient Delivery

PPCs combine multivalent binding sites, interfacial activity, and network‐forming capacity (Tao et al. 2024), enabling the retention of aroma compounds, physicochemical stabilization, and the controlled release of bioactive compounds (Figure 5). Recent reviews have highlighted the importance of protein‐based and polysaccharide–protein delivery systems in improving the bioavailability and functional stability of nutraceuticals (Cao et al. 2025). These properties make PPCs promising platforms for functional foods, nutrient delivery, food packaging, and oral care (Xu et al. 2020). For example, protein–polysaccharide conjugates from sugar beet pulp can form stable emulsions and gel‐like high internal phase emulsions (HIPEs) under stress, indicating their potential in clean‐label formulations (Lin et al. 2023).

FIGURE 5.

Application in functional food and drug delivery.

In nutrient delivery, PPCs can encapsulate both hydrophilic and lipophilic bioactives through non‐covalent interactions, interfacial adsorption, and network entrapment. SPI–citrus pectin systems have been used to deliver β‐carotene and resveratrol (Zhou et al. 2025), while soy protein–polysaccharide composites show high encapsulation efficiency (Wu et al. 2022). Microbiota‐responsive systems, such as GlycoCaging, further demonstrate how polysaccharide‐based structures can improve targeted delivery in gut‐related diseases, including inflammatory bowel disease (Ma et al. 2025). Polyphenol–polysaccharide microgels also provide structural integrity and oxidation protection in food systems (Cortés‐Ferré et al. ²⁰²⁵).

PPCs are also promising for food preservation and packaging applications, as they can serve as bioactive reservoirs and protective matrices. Fish gelatin–orange peel pectin films enhance cheese stability and antioxidant capacity (J. Li et al. ²⁰²⁵), and plum seed conjugates improve essential oil encapsulation (Xue et al. 2025). In pharmaceutical and oral care applications, PPC‐based emulsions, hydrogels, microcapsules, and nanoparticles may support stable delivery through receptor‐mediated uptake and intracellular transport (Ma et al. 2020). However, most current studies still rely on simplified model systems. Future work should therefore validate plant‐derived PPCs in real food matrices, with particular attention to processing stability, sensory impact, release behavior, safety, and scalability. Representative applications of PPCs in food, nutrient delivery, and biomedical systems are summarized in Table 2.

TABLE 2.

Multifunctional applications in food, nutrition delivery, and biomedical systems.

Source	Type of complex	Application form	Applicable conditions/characteristics	Reference
Soy protein isolate + citrus pectin + citrus flavonoids (CF)	Protein–polysaccharide–polyphenol	Antimicrobial edible films for food packaging	Sustained release of CF, enhanced antioxidant and antimicrobial activity, extended shelf‐life of grapes and pork	Guo et al. (2024)
Soy soluble polysaccharide + casein + curcumin	Ternary complex nanoparticles	Oral delivery system for curcumin	High curcumin loading (97%, up to 48.6%), stable (30 days, pH 2–7)	Xu et al. (2020)
Pea protein + corn fiber polysaccharide	Core‐shell composite nanoparticles		High encapsulation efficiency, improved dispersibility and stability (pH/thermal)	Wei et al. (2020)
Soy protein isolate (SPI) + citrus/apple pectin	Maillard reaction	Food ingredient/emulsifier	Improved solubility and emulsifying properties, showed higher grafting extent	Ma et al. (2020)
SPI + soy soluble polysaccharide	Core‐shell nanocomplex	Oral delivery system for hyperoside	Encapsulation efficiency up to 85.6% at pH 3.5	Wu et al. (2022)
Soy soluble polysaccharide	Maillard reaction	Oil‐in‐water emulsions (citral delivery)	Enhanced physical and thermal stability (95°C, 30 min), stable under simulated gastric fluid (2 h, 70% citral retained)	Yang et al. (2015)
SPI/soy peptide (SP) + ginseng polysaccharide	Maillard reaction	Emulsifier for oil‐in‐water emulsions	Emulsifying activity, high zeta potential (−50.2 mV), long‐term stability (21 days, no creaming)	Tao et al. (2024)
Plum seed protein isolate + polyphenols+ wolfberry polysaccharides	Modified protein complex	Essential oil emulsions and capsules	Improved emulsifying and encapsulating ability	Xue et al. (2025)
Protein–polysaccharide conjugates from sugar beet pulp	Core‐shell	Emulsifier for oil‐in‐water and HIPE emulsions	Droplet size 0.44 µm, stable at 60°C, 5 days	Lin et al. (2023)
Whey protein isolate + okra polysaccharide	Blend films	Edible packaging films	Improved flexibility, elongation, and oxygen barrier	Prommakool et al. (2011)
Green tea polysaccharide conjugates	Natural form	Oil‐in‐water emulsions	Stable emulsions at 2–3 wt%, protective effect on EGCG and epigallocatechin (EGC)	Chen et al. (2019)
Lycium barbarum	Polysaccharide–protein conjugates (subcritical water)	Stabilizer for selenium nanoparticles	Prevented aggregation	Zhang et al. (2022)
Bamboo leaf	Alkali‐extracted polysaccharide conjugates	High internal phase	Stable at 1.0–2.5 wt% with 80% oil phase, 30 days storage	Chen et al. (2023)
Dendrobium officinale polysaccharide (DOP) + hemp seed protein (HSP)	Alkali‐induced polysaccharide–protein gels	Dysphagia‐friendly food formulation	Tunable gel texture, enhanced viscoelasticity, antioxidant activity, cytocompatibility	Ding et al. (2025)

7. Perspectives

PPCs provide a versatile platform for connecting molecular interactions with sensory quality, food stability, and health‐related functions. Future research should move beyond the characterization of individual conjugates and focus on establishing clearer structure–function relationships across diverse PPC systems. Particular attention should be given to how molecular weight, branching degree, charge density, binding mode, and spatial conformation determine sensory regulation, interfacial behavior, digestive stability, and bioactive delivery. Such mechanistic insights will facilitate the transition of PPCs from empirically developed ingredients to rationally designed multifunctional food components.

Another important research direction is the development of controllable and food‐compatible fabrication strategies. Although chemical conjugation and nanotechnology‐assisted methods can provide structural precision, their use in foods may be limited by reagent safety, regulatory acceptance, and scalability. Therefore, green and mild technologies, such as enzymatic modification, fermentation, ultrasound‐assisted processing, microwave‐assisted treatment, and controlled thermal processing, deserve greater attention. These approaches may enable the formation of PPCs with improved stability, color protection, flavor retention, texture control, and nutrient delivery while maintaining clean‐label and consumer‐friendly characteristics.

The behavior of PPCs in real food systems needs further study. Most studies use simplified model systems, while real foods contain many different components that can affect PPC formation and function. Future studies should therefore evaluate PPCs under realistic processing, storage, oral, gastric, intestinal, and microbial fermentation conditions. This is particularly important for understanding the balance between structural stability and controlled release, as well as the effects of PPCs on sensory perception, nutrient bioaccessibility, gut microbiota, and long‐term safety.

From an application perspective, PPCs have broad potential in functional foods, plant‐based products, active packaging, oral care, and nutraceutical delivery systems. Their multivalent binding sites and tunable networks allow simultaneous regulation of aroma retention, pigment stability, texture formation, antioxidant protection, and bioactive compound release. However, future work will require standardized characterization methods, quantitative evaluation of sensory and functional properties, and clearer links between laboratory‐scale performance and industrial‐scale production. Interdisciplinary integration of food chemistry, colloid science, sensory science, nutrition, and materials engineering will be essential for designing next‐generation PPC‐based food systems.

8. Conclusions

This review summarizes the formation mechanisms, structural characteristics, sensory roles, biological activities, and food applications of PPCs. PPCs can be generated through non‐covalent interactions, covalent conjugation, ionic coordination, interfacial assembly, and processing‐induced molecular rearrangement. These interactions regulate molecular conformation, charge distribution, network formation, and interfacial stability, thereby determining their performance in complex food systems.

Overall, PPCs play multifunctional roles in improving food quality by regulating color, aroma, taste, texture, oxidative stability, and nutrient delivery. Their functions are not determined by polysaccharides alone but arise from coordinated interactions with proteins, peptides, polyphenols, lipids, metals, and other small molecules. By linking structural design with sensory enhancement, bioactivity, and processing tolerance, PPCs represent promising multifunctional ingredients for developing sustainable, stable, and health‐oriented food products.

Author Contributions

Jinrui Liu: writing – review and editing, writing – original draft, conceptualization, validation, methodology, visualization. Yanqing Zhang: conceptualization, funding acquisition, data curation, resources. Xiaotong Zhao: data curation, writing – original draft, writing – review and editing, investigation. Ting Zhang: software, formal analysis, project administration. Junbo Xie: conceptualization, writing – review and editing, supervision.

Conflicts of Interest

The authors declare no conflicts of interest.