Towards Sustainable Biopolymer Innovation: A Review of Opuntia ficus-indica Mucilage

Abstract

Natural biopolymers, such as the mucilage of Opuntia ficus-indica (OFI), are gaining attention as sustainable alternatives to synthetic materials due to their biocompatibility, biodegradability, and functional versatility. Opuntia ficus-indica mucilage, a polysaccharide-rich hydrocolloid extracted from OFI cladodes, has emerged as a promising biomaterial with diverse applications. In the food sector, its use in edible coatings and films can extend shelf life, reduce moisture loss, and deliver bioactive agents, aligning with eco-friendly packaging initiatives. Its physicochemical properties, including high water-holding capacity, viscosity, thermal stability, and film-forming ability, also support potential uses in pharmaceuticals, cosmetics, biomedicine, and environmental remediation. Despite this promise, large-scale adoption is limited by variability in composition, lack of standardized processing, functional inconsistencies, and competition with synthetic polymers. However, the sustainable cultivation of OFI, its resilience under drought, and the possibility of valorizing cladode waste strengthen its profile within circular economy frameworks. This review synthesizes current knowledge on the extraction, properties, and applications of OFI mucilage, while identifying key research gaps and technological challenges. It emphasizes the need for interdisciplinary research and industrial collaboration to overcome barriers and unlock the full potential of OFI mucilage as a high-performance, eco-friendly biopolymer for future applications.

1. Introduction

In light of growing environmental concerns and increasing global commitment to sustainability, the development of natural biopolymers has emerged as a scientific and industrial priority. Synthetic polymers, which dominate sectors such as packaging, agriculture, and biomedicine, are primarily derived from fossil-based resources and are notoriously persistent in the environment [1]. Their resistance to degradation contributes significantly to global pollution burdens, with about 460 million tonnes of plastic waste produced annually, about 40–45% of which arises from packaging materials [2]. These materials accumulate in terrestrial and marine ecosystems while leaching harmful substances and emitting greenhouse gases when incinerated. In contrast, biopolymers derived from renewable sources such as plants, microbes, or animals offer advantages including biodegradability, biocompatibility, and reduced toxicity, making them attractive alternatives in efforts to mitigate ecological harm and reduce reliance on non-renewable materials [3].

Among the array of emerging bio-based materials, plant-derived hydrocolloids have garnered increasing attention due to their functional versatility and environmental compatibility [4]. The global market for biopolymer-based packaging was valued at USD 14.45 billion in 2024 and projected to exceed USD 29 billion by 2032, reflecting growing consumer and industrial demand for sustainable materials [5]. In this context, mucilage from Opuntia ficus-indica (L.) Mill. (OFI) has been identified as a particularly promising natural biopolymer. This cactus, commonly known as the prickly pear, is a drought-tolerant species capable of thriving on marginal lands with minimal inputs, making it an ideal candidate for low-impact, sustainable biomass production. O. ficus-indica mucilage exhibits a distinctive combination of physicochemical attributes, including high viscosity, hydrogel formation, film-forming capacity, and biodegradability, all of which position it as a multifunctional material for diverse applications ranging from food and pharmaceuticals to environmental engineering.

1.1. Opuntia ficus-indica: Agronomic and Ethnobotanical Significance

Opuntia ficus-indica, a member of the Cactaceae family, is one of the most widely cultivated cactus species globally [6]. Its flattened, fleshy cladodes (modified stems adapted for water storage) enable it to withstand prolonged drought, nutrient-poor soils, and high temperatures with minimal irrigation or fertilization [7]. This resilience is attributed to its crassulacean acid metabolism (CAM) photosynthetic pathway and a shallow, fibrous root system that efficiently captures moisture [8]. In addition to its agronomic robustness, OFI contributes to ecosystem services, including soil conservation, erosion control, biodiversity enhancement, and microclimate regulation [6].

Opuntia ficus-indica (OFI) has also had a long history of culinary and medicinal use. The cladodes are consumed as vegetables or processed into flour, while the fruits are used in juices, jams, and syrups [9]. Its high moisture content also makes it a valuable source of livestock feed, often requiring minimal processing [10]. Ethnobotanical evidence highlights its use in traditional medicine, particularly in regions such as Mexico, where various plant parts are employed in managing burns, diabetes, edema, asthma, and hypertension [11]. Similar uses have been reported globally, for instance, the fruit is used in kidney stone and diabetes management in Turkey, and different parts of the plant are applied in ulcer and gastrointestinal treatment in China [12,13]. These diverse agronomic and ethnobotanical attributes highlight OFI as a resilient and multifunctional crop and also provide a compelling rationale for the increasing scientific interest in its mucilage.

1.2. O. ficus-indica Mucilage: Composition and Functional Significance

In recent years, scientific interest has increasingly focused on a previously underutilized component of OFI, which is its mucilage. This mucilage is a gelatinous polysaccharide-rich extract found predominantly in the medulla of the cladodes. It has demonstrated considerable promise across various fields, including food science, pharmaceutical technology, materials engineering, and environmental remediation. Although its composition varies with factors such as extraction method, cultivar, and geographic origin [14], OFI mucilage is generally characterized as a high-molecular-weight heteropolysaccharide [15]. Structurally, it consists of a galacturonic acid backbone with side chains of galactose, rhamnose, arabinose, and xylose [16,17]. It also contains other bioactive compounds and essential minerals such as calcium, potassium, and magnesium, although anti-nutritional factors like calcium oxalate crystals have also been observed [18].

These compositional features contribute to the properties of OFI mucilage, including its hydrogel-forming capacity, water-binding ability, emulsification potential, and mechanical stability. These traits make it an ideal candidate for use in biodegradable films, encapsulation systems, wound dressings, and flocculants [19,20]. Notably, it exhibits superior film-forming properties and biocompatibility compared to other plant mucilages, and its sustainable production is further supported by the rapid cladode regeneration of the parent plant, even under water-limited conditions [21].

As industries increasingly shift toward bio-based and circular economy models, OFI mucilage has garnered attention as a green alternative to petroleum-derived polymers. Its utility spans moisture regulation in food packaging, controlled drug release, dermal applications, and pollutant removal in wastewater systems. Despite its potential, current research remains fragmented, with most studies focusing on isolated functionalities or narrow use-cases. Critical challenges such as composition variability, standardization of extraction, functional reproducibility, and scalability continue to hinder its broader industrial uptake.

1.3. Scope and Objectives of the Review

In response to these challenges and opportunities, this review provides a comprehensive synthesis of current research on OFI mucilage. It explores the sources, extraction techniques, physicochemical characteristics, and current and emerging applications of OFI mucilage across multiple industries. The review also critically examines its advantages over conventional and plant-based polymers, identifies key technological and regulatory bottlenecks, and outlines strategic directions for future research and industrial integration. By bridging insights from plant sciences, materials engineering, environmental sustainability, and bioeconomics, this work aims to inform the development of OFI mucilage as a commercially viable, high-performance biopolymer for a greener future.

2. Materials and Methods

2.1. Data Sources

This review was conducted utilizing a targeted literature search across multiple reputable academic databases to ensure comprehensive coverage of the current and emerging applications of OFI mucilage. The primary sources included ScienceDirect, Web of Science, Scopus, and Google Scholar. Additionally, relevant gray literature such as academic theses, dissertations, and institutional reports was considered to capture emerging or unpublished data. Patents were also reviewed as formally indexed sources of applied innovation. The reference lists of selected articles were manually screened for additional relevant studies not indexed in major databases.

To maintain data reliability, all included sources were evaluated based on their scientific relevance, methodological transparency, and clarity of reported results. Only documents providing verifiable data, experimental details, or explicit application outcomes were included to ensure comparability and credibility across information sources.

2.2. Search Terms

A combination of free-text keywords was employed. The core search terms included “Opuntia ficus-indica” OR “prickly pear cactus,” “mucilage” OR “plant mucilage” OR “cactus mucilage,” “applications” OR “uses” OR “functional properties,” “biopolymer” OR “hydrocolloid,” “drug delivery” OR “encapsulation,” “wound healing” OR “scaffold” OR “tissue engineering,” “environmental” OR “water flocculant” OR “construction admixture,” and “cosmetics” OR “prebiotic” OR “fat replacer.” Boolean operators (AND, OR) and truncation were utilized to enhance the search breadth and specificity. Truncation symbols were adapted to the syntax requirements of each database. Searches were limited to studies published between 2000 and 2025 to reflect recent advancements and trends.

2.3. Inclusion and Exclusion Criteria

To ensure the relevance and quality of data included in this review, the following inclusion criteria were applied:

• Studies focusing on the chemical, functional, or application-related properties of mucilage derived specifically from OFI.
• Articles evaluating the use of OFI mucilage in food, pharmaceutical, biomedical, cosmetic, or environmental applications.
• Research papers published in peer-reviewed journals, as well as authoritative book chapters, patents, and technical reports.
• Studies written in English or with accessible English translations.
• Both experimental studies and review articles were included if they provided new insights or critical analysis relevant to the topic.

Studies were excluded if they:

• Focused on other cactus species or plant gums not related to OFI.
• Did not clearly differentiate OFI mucilage from other components.
• They were duplicated, outdated, or lacked methodological clarity.

2.4. Data Extraction

The following variables were recorded from the included studies:

• Publication details: Author(s), year, journal, country;
• Plant material: Source and part used (e.g., cladode medulla, peel, fruit);
• Extraction method: Technique, solvent, temperature, drying method;
• Characterization: Physicochemical properties (e.g., viscosity, thermal stability, functional groups);
• Application area: Food, pharmaceuticals, environmental, cosmetics, biomedicine;
• Key findings: Efficacy, performance, limitations, novelty.

To enhance the reliability and transparency of the data synthesis, data extraction was carried out independently by two reviewers to ensure accuracy and consistency. Extracted information was cross-validated, and any discrepancies were resolved through discussion and consensus. Data were synthesized thematically under categories aligned with the major sections of the review. Where applicable, data were cross-compared to identify trends, knowledge gaps, and future research directions.

3. Results and Discussion

3.1. Extraction of Mucilage from O. ficus-indica

The extraction of OFI mucilage is a crucial step in valorizing this bioresource for applications in agriculture, food packaging, biopolymer formulation, and wastewater treatment [22]. Mucilage from OFI, which is a complex polysaccharide-rich hydrocolloid, is majorly extracted from the cladodes (pads) of the plant using aqueous methods. Nevertheless, the yield, phytochemical composition, and functional properties of mucilage extracted from OFI are influenced by a wide range of factors, among which the extraction method is particularly significant [20]. To this end, the key process parameters used in various studies on mucilage extraction have been summarized in

Table 1. Summary of mucilage extraction protocol conditions, processing conditions, and yields of mucilage from different parts of Opuntia ficus-indica.

Plant Part	Thermal Pre-Treatment	Mechanical Disintegration	Centrifugation	Precipitation	Drying	Yield	References
Cladode	None	Pressing	10,000 rpm for 10 min	Ethanol (1:3)	Oven-dried (105 °C for 24 h)	NA	[26]
Cladode	None	Pressing	No	Ethanol (2:3)	Oven-dried (50 °C for 24 h)	14%	[19]
Cladode	None	Blending	7000 rpm for 1 h	None	Freeze-dried (NA)	NA	[15]
Cladode	Microwave	Milling	4000 rpm for 15 min	Ethanol (1:3)	Freeze-dried (−55 °C for 12 h)	Up to 25.6%	[27]
Cladode	Microwave	Blending	Yes (NA)	None	Freeze-dried (NA)	Up to 20.9%	[28]
Cladode	None	Blending	No	None	Spray-dried (inlet temp. of 135 °C)	1.17%	[29]
Cladode	None	Milling	Yes (NA)	Ethanol (1:2)	Oven-dried (35 °C for 40 min)	15.69%	[20]
Cladode	Hot water	None	Yes (4000 rpm for 20 min)	Ethanol or isopropanol (2:3)	Oven-dried (40 °C for 24 h)	Isopropanol (23.2%) Ethanol (19%)	[30]
Fruit	Hot water	None	Yes (2500 rpm for 15 min)	Ethanol (1:3)	Oven-dried (30 °C for 48 h)	9.92%	[23]
Cladode	None	Pressing	Yes (10,000 rpm for 30 min)	Ethanol (1:3)	Oven-dried (105 °C for 24 h)	NA	[31]
Fruit peel	None	Pressing	No	Ethanol (1:3)	Oven-dried (50 °C for 3 h)	NA	[25]
Fruit peel	Hot water	Ultrasound sonication	No	NA	NA	Up to 41.7% Up to 33.6%	[24]
Cladodes	Microwave	Blending	No	Ethanol (1:3)	Oven-dried (NA)	18.8%	[32]
Cladodes	Hot water	Ultrasound sonication	Yes (4000 rpm for 20 min)	NA	Oven-dried (45 °C for 24 h)	19 to 22.8%	[33]
Cladodes	None	Crushing	Yes (4500 rpm for 30 min)	Ethanol (1:3)	Freeze-dried (NA)	NA	[34]
Cladodes	Microwave	Blending	Yes (8117 rpm for 15 min)	None	NA	Up to 26%	[35]
Cladodes	Microwave	None	Yes (10,100 rpm for 15 min)	None	Freeze-dried (72 h)	NA	[36]

NA: Not Available; Yield basis varies across studies, wet mucilage yield (% w/w) per fresh cladode weight in [28,33]; dry mucilage yield (% w/w) per dehydrated cladode weight in other studies.

, while an overview of the process is represented in Figure 1. Moreover, it is worth noting that there is no strict categorization of these methods into “traditional” and “modern” approaches in the literature, as many studies combine elements from both to optimize yield, purity, and functional performance. Hence, Table 1 identifies the core processing steps adopted in each study, the conditions applied, and the resulting mucilage yield. Notably, while mucilage is most commonly extracted from the cladodes of OFI, Table 1 also highlights studies that have successfully extracted mucilage from other plant parts, including the fruit pulp and peels [23,24,25].

A frequently utilized pretreatment method involves the thermal processing of the internal tissue (medulla) of cladodes by boiling them in water. This process serves to soften the plant matrix, thereby enhancing the release of mucilage. Such thermal pretreatment has been accomplished through conventional heating [27] or microwave-assisted techniques [36]. Thermal pretreatment softens cell wall matrices and enhances polysaccharide release by promoting pectin solubilization and water diffusion [28]. However, prolonged exposure to heat may induce partial depolymerization of galacturonic acid chains, leading to reduced viscosity and alterations in the molecular weight distribution of the extracted mucilage [20]. Consequently, the use of thermal pretreatment represents a trade-off between enhanced yield and the potential loss of rheological and structural integrity. Numerous studies have therefore omitted the heating step, opting instead for mechanical methodologies, including pressing, blending, milling, or maceration of the peeled and diced cladodes to generate a viscous gel [15,19,26]. Notably, in studies where thermal pretreatment was implemented, mechanical disintegration frequently followed as a supplementary procedure [28,32].

Following extraction, centrifugation is commonly employed to separate soluble mucilage from insoluble plant debris, which includes cell wall fragments and fibers. However, the centrifugation parameters (e.g., speed and duration) exhibit considerable variability across different studies. The documented trend indicates that the application of thermal pretreatment results in a softened matrix that requires less rigorous centrifugation. For instance, Otálora et al. [31], who omitted the heating step, centrifuged at 10,000 rpm for 30 min, whereas Felkai-Haddache et al. [27], who incorporated heating, achieved effective separation at 4000 rpm for 15 min. This observation suggests that thermal softening of the plant matrix diminishes resistance to separation, thereby reducing the requirement for high-speed centrifugation. This step is often followed by precipitation.

Typically, ethanol is widely utilized for precipitating mucilage from the aqueous extract, usually in ratios ranging from 1:2 to 2:3 (mucilage solution to ethanol). Ethanol facilitates precipitation by decreasing the solubility of mucilage polysaccharides and also contributes to decolorization, yielding a whitish mucilage that resembles conventional biopolymers and enhances its acceptability for industrial applications [34]. Some studies have investigated alternative solvents; for example, Mannai et al. [37] reported that substituting ethanol with isopropanol resulted in an improved yield, increasing from 19% to 23.2%, while still maintaining satisfactory depigmentation [30]. The choice of solvent dictates the ionic strength and dielectric environment of the process, influencing the yield and recovery of phenolics and mineral ions that contribute to the functional properties of OFI mucilage. Nevertheless, not all studies incorporate the alcohol precipitation step. In such instances, the resulting mucilage retains a greenish hue due to the presence of residual chlorophyll and other pigments [29,38]. This omission is often motivated by the desire to preserve antioxidant compounds, such as polyphenols, which may be lost during alcohol precipitation [24,33]. For example, Hernández-Carranza et al. [24] eliminated the use of ethanol and instead employed hot water extraction under continuous magnetic stirring, achieving a yield superior to that obtained via ultrasound-assisted extraction alone [24]. Notably, the combination of hot water and ultrasound treatment has also been shown to enhance extraction efficiency compared to hot water extraction alone [33]. Once extracted, the mucilage must undergo drying to yield a stable powder.

Among the various drying techniques, oven drying is the most prevalent due to its accessibility and cost-effectiveness. Freeze-drying is preferred for preserving phytochemical integrity; however, it is less frequently utilized due to its higher associated costs. Conversely, while spray drying can be an efficient method for mucilage recovery when process parameters are optimized, it has been infrequently reported in the literature, appearing in only one of the studies reviewed. This limited use may reflect preference for low-temperature drying methods, given that excessive heat can potentially degrade thermolabile phytochemicals [39]. The drying method also exerts a significant influence on mucilage yield. Although comparable yields of between 10 and 23% have been reported in the literature for oven-dried and freeze-dried samples (Table 1), a spray-dried sample analyzed by Reyes-Ocampo et al. [29] exhibited a substantially lower yield of 1.19%. It is important to note that yield calculations were not standardized across studies. Specifically, two studies [28,33] expressed yield as the wet weight of extracted mucilage relative to fresh cladode weight, whereas other studies reported yield as the dry weight of mucilage relative to dehydrated cladode/fruit/fruit peel biomass. This methodological variation, in addition to variations in plant parts used for mucilage production, may have contributed significantly to the apparent discrepancies in reported yields. Otálora et al. [26] reported oven drying at a relatively high temperature of 105 °C for 24 h. These parameters were specific to the cited methodology and may have been intended for moisture removal rather than preservation of functional integrity. Such conditions, while effective for rapid dehydration, could potentially affect the structural and rheological properties of the mucilage.

While the extraction protocol is a crucial determinant of mucilage yield and quality, it is not the sole influencing factor. Genetic and cultivar differences exert a considerable impact as well. Du Toit [40] emphasized that mucilage yield varies significantly among cultivars and is not directly correlated with cladode size or moisture content. Consequently, when comparing yields across studies, it is imperative to consider the specific cultivar employed, a detail that is often overlooked in the literature but is essential for reproducibility and standardization.

3.2. Key Physicochemical Properties of O. ficus-indica Mucilage

Mucilage extracted from OFI exhibits a distinctive array of physicochemical properties that underpin its versatility across various industrial sectors, including food, pharmaceuticals, cosmetics, and biomaterials [41]. These properties can be attributed to its complex heteropolysaccharide composition, which typically includes galacturonic acid, arabinose, rhamnose, xylose, and galactose, in addition to associated proteins and minerals [14,17]. The molecular arrangement and branching pattern of these sugars (Figure 2) impart functional characteristics such as viscosity modulation, water-binding capacity, thermal stability, and biocompatibility, thereby rendering OFI mucilage a valuable natural polymer [42]. While these properties may vary depending on extraction methods, plant part used, and environmental factors affecting cultivation [20,43], several core traits consistently stand out. These include high viscosity, high water retention, thermal stability, and biocompatibility, all of which contribute to the growing interest in OFI mucilage as a sustainable biomaterial [44].

Viscosity represents a fundamental functional property of mucilage influencing its potential as a thickening, gelling, stabilizing, or emulsifying agent in diverse formulations. Mucilage derived from OFI typically exhibits non-Newtonian, shear-thinning behavior, characterized by a decrease in viscosity under shear stress. This property is particularly desirable in food and pharmaceutical applications where flowability is important under processing conditions [30,45]. Research has demonstrated that the viscosity of OFI mucilage can be significantly influenced by factors such as molecular weight, extraction temperature, and pH [15,46]. Its high molecular weight and branching contribute to strong intermolecular interactions, forming a dense three-dimensional network in aqueous solutions. This makes it particularly useful in applications like stabilizing emulsions, suspending solids, or controlling the release of active agents in drug delivery systems [47]. Moreover, the viscosity of OFI mucilage is comparable to that of other natural gums, such as xanthan, guar, and Arabic gum, under optimized conditions; however, it may vary depending on factors including concentration, pH, and ionic strength [48]. This positions OFI mucilage as a viable competitor among established conventional polymers.

One of the most notable features of OFI mucilage is its exceptional water-holding capacity (WHC), which has been reported to typically exceed that of many other hydrocolloids [49]. This capacity is attributed to its hydrophilic functional groups, particularly the carboxyl and hydroxyl groups on its uronic acid residues, which facilitate strong hydrogen bonding with water molecules [50,51]. Consequently, this property makes OFI mucilage particularly advantageous in applications aimed at hydration, like soil conditioning, wound healing materials, moisture-retaining food formulations, and cosmetic products. In agricultural applications, for instance, the water retention ability of its parent plant helps improve soil moisture retention in arid zones, reducing the need for frequent irrigation [6]. In the pharmaceutical and biomedical context, its ability to retain water would support moist wound healing environments, which are known to enhance tissue regeneration [52]. Moreover, this hydrophilic behavior significantly contributes to its swelling index, a critical parameter for drug delivery systems in which controlled swelling influences release kinetics [53].

Thermal stability is crucial for the application of mucilage in high-temperature industrial processes, including extrusion, pasteurization, and spray drying. OFI mucilage has been found to exhibit moderate thermal resistance, retaining its structural integrity and functionality up to a temperature of 200 °C, depending on concentration and pH [34]. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies have shown that OFI mucilage undergoes an initial weight loss due to water evaporation, followed by degradation that begins at onset temperatures near 200 °C, indicating moderate thermal stability [19,38]. This thermal resilience can be attributed to the stable polysaccharide backbone and its interactions with minerals such as calcium and magnesium, which enhance crosslinking and structural rigidity [14]. As a result, OFI mucilage is deemed suitable for integration into thermal processing systems within both the food and polymer industries. Furthermore, its thermal behavior supports its application in film formation, particularly in the development of biodegradable packaging materials, where stability under storage and transportation conditions is crucial [14].

Another significant characteristic that enhances the utility of OFI mucilage in various biological systems is its biocompatibility. Biocompatibility refers to the ability of a substance to interact with biological systems without inducing toxicity or immunogenic responses, which is a fundamental requirement for any material intended for biomedical or pharmaceutical applications. Mucilage from OFI has demonstrated excellent biocompatibility, supported by in vitro and in silico studies showing low cytotoxicity and favorable interactions with mammalian cells [54]. This property stems from its natural origin, non-toxic sugar composition, and lack of synthetic additives or allergens. Consequently, OFI mucilage has promising applications in drug delivery, wound dressings, and tissue scaffolds, where it could support cell adhesion, proliferation, and moisture retention without triggering adverse reactions [55]. Moreover, it is biodegradable, reducing the risk of long-term accumulation in biological systems or the environment. These attributes position OFI mucilage as a viable alternative to synthetic polymers in a variety of health-related applications, aligning with the growing demand for eco-friendly biomaterials.

Key physicochemical properties of OFI mucilage, which underpin its versatility across numerous applications, are highlighted in Figure 3. These features demonstrate its functional performance and reinforce its potential as a sustainable, plant-based alternative to synthetic polymers and conventional hydrocolloids.

3.3. Comparative Advantages of Mucilage from OFI over Other Common Plant Mucilages

Plant-derived mucilages have gained significant attention in recent years as natural, biodegradable alternatives to synthetic polymers for applications spanning food technology, pharmaceuticals, agriculture, and environmental remediation [56]. Common sources include flaxseed, okra, chia, psyllium, and aloe vera, all of which provide hydrocolloids rich in complex polysaccharides with water-binding and gel-forming capacities. In comparison, mucilage from OFI has emerged as particularly versatile due to its combination of high water-holding capacity, thermal stability, film-forming ability, and ecological adaptability [46]. In addition, OFI mucilage offers advantages in terms of functional performance, stability, biocompatibility, extraction sustainability, and yield, thereby reinforcing its potential as a next-generation biomaterial.

Table 2. Comparative advantages of O. ficus-indica mucilage over other common plant mucilages.

Mucilage Source	Key Properties	Limitations	Advantages of OFI Mucilage	References
Flaxseed (Linum usitatissimum)	Good water-binding; high viscosity	Lower uronic acid content; less WHC	Higher WHC due to uronic acids and branched heteropolysaccharides	[22,49,56]
Okra (Abelmoschus esculentus)	Emulsifying and thickening	Low thermal stability (Tg = 50 °C, Mp = 166 °C)	Maintains viscosity and structural integrity near 200 °C	[19,57,58]
Chia Seed (Salvia hispanica)	Excellent gelation; emulsion stabilization	Less flexible films, poor transparency	Forms flexible, and transparent films with higher elongation at break	[38,59,60]
Psyllium (Plantago ovata)	High fiber, gelling agent	Allergenic reactions due to protein contaminants	Hypoallergenic, non-toxic, highly biocompatible	[44,61,62]
Aloe vera	Hydrating, bioactive-rich mucilage	High cultivation inputs (controlled growth and water requirements)	Thrives in arid zones; sustainable, high-yield; rapid cladode regrowth	[6,21,63]

WHC: Water Holding Capacity; Tg: Glass transition temperature; Mp: Melting point.

summarizes these comparative traits, underscoring OFI mucilage’s distinct position among plant-derived hydrocolloids and its potential as a scalable, eco-friendly polymer for industrial applications.

3.4. Current Applications of O. ficus-indica Mucilage

The distinctive physicochemical attributes of OFI mucilage have translated into a wide spectrum of practical applications. These applications include established roles in food systems, where it functions as a thickener, stabilizer, and edible coating material; biomedical and pharmaceutical domains, where it supports drug delivery, wound healing, and tissue scaffolding; and environmental sectors, where it serves as a natural flocculant, bio-admixture, and soil stabilizer (Figure 4). Importantly, its plant-based, biodegradable, and sustainable nature positions OFI mucilage as an attractive alternative to synthetic polymers, aligning with global trends toward eco-friendly and health-conscious materials. The following subsections highlight both established and emerging applications across food, health, and environmental industries.

3.4.1. Food Industry

The global shift toward natural, biodegradable, and health-promoting ingredients in food systems has led to growing interest in plant-derived hydrocolloids [64,65]. Among these, mucilage from OFI has gained significant attention; it is currently applied in a variety of roles, including as a thickening and gelling agent, edible coating material, and encapsulation matrix for bioactive compounds [66]. As research continues to unveil new functionalities, the role of OFI mucilage is anticipated to expand further, especially in the development of next-generation food systems.

Precisely, OFI mucilage has been recognized as a potential natural thickener and gelling agent within the food industry, attributed to its high viscosity and shear-thinning behavior, which enables it to enhance the texture and mouthfeel of diverse liquid and semi-solid products [66]. The polysaccharides present in OFI mucilage interact with water molecules to form viscoelastic gels, which can be used to stabilize sauces, soups, dairy products, beverages, and bakery fillings [45]. A study investigating the replacement of gelatin with OFI mucilage in marshmallow production found that both materials performed comparably across key parameters, suggesting that mucilage presents a cost-effective alternative [67]. Similarly, OFI mucilage has been assessed for its ability to replace artificial thickeners in the production of probiotic cream cheese [68]. The results revealed excellent acidity, protein, fat, moisture, ash, and probiotic count, which met the Brazilian legislation standards. Unlike synthetic thickeners (e.g., carboxymethyl cellulose) or animal-derived agents like gelatin, OFI mucilage offers a plant-based, vegan-friendly, and clean-label alternative. Its thermal and pH stability further enhances its applicability across a broad spectrum of food matrices [69].

Its film forming ability has been explored for food packaging applications. Thus, this property makes it highly suitable for use in edible coatings and biodegradable films, which serve as protective barriers for fresh fruits, vegetables, and minimally processed foods [19]. These coatings help reduce moisture loss, delay oxidation, and inhibit microbial growth, thereby extending shelf life [41]. Studies by Shinga and Fawole [36] have shown the ability of OFI mucilage to extend the shelf life of banana through delayed ripening and regulation of cell wall softening enzymes, demonstrating its application in the postharvest preservation of climacteric fruits. Other studies have suggested that OFI mucilage-based coatings can be enhanced with essential oils, nanoparticles, or antioxidants (e.g., cinnamon, rosemary, or ascorbic acid) to create active packaging systems with improved antimicrobial or antioxidant functions [70]. Moreover, the mechanical strength and flexibility of mucilage-based films make them a promising sustainable alternative to conventional plastic wraps, particularly when processed via electrospinning, thereby advancing eco-friendly food packaging solutions [44]. O. ficus-indica mucilage has also emerged as an alternative viable wall material for encapsulation of volatile bioactive compounds in food packaging. Encapsulation is a key technology in the development of functional and fortified foods, where active compounds such as probiotics, vitamins, polyphenols, and essential oils need to be protected from degradation and controlled in their release [71]. O. ficus-indica mucilage has thus been successfully used as a natural encapsulant, owing to its hydrogel-forming capacity, biocompatibility, and low toxicity [71]. For instance, OFI mucilage has been evaluated for its encapsulation efficiency in stabilizing sunflower oil to facilitate industrial-scale transport and supply [47]. This study demonstrated that OFI mucilage compared favorably with chitosan (a widely used encapsulation material), achieving both higher encapsulation efficiency and a more uniform capsule size distribution. Similar results were obtained in the encapsulation of anthocyanins from Solanum melongena, where 73% of the core material was viable after four months compared to 30% in the unencapsulated material [71]. Despite the limited number of studies exploring the encapsulation potential of OFI mucilage, the existing evidence is promising, underscoring its suitability as an industrial encapsulating agent when processed through innovative techniques such as freeze-drying, ionic gelation, and emulsification.

3.4.2. Pharmaceuticals and Biomedicine

Natural polymers like OFI mucilage have garnered significant interest in pharmaceutical and biomedical applications owing to their biocompatibility, biodegradability, non-toxicity, and renewable origin [72]. With its composition, OFI mucilage exhibits excellent hydrogel- and film-forming capabilities, moisture retention, and bio-adhesiveness, making it an attractive candidate for drug delivery systems, wound dressings, and tissue engineering scaffolds [73]. Additionally, this mucilage has demonstrated inherent antioxidant, anti-inflammatory, and antimicrobial properties, which in turn enhance its therapeutic potential [13]. Its low immunogenicity, high water-holding capacity, and ability to create protective, moist environments also render it suitable for both topical and internal biomedical applications. Despite these encouraging characteristics, there is a paucity of research investigating its practical applications, with limited evidence substantiating its efficacy in wound healing. This situation underscores the necessity for further studies to validate the viability of OFI mucilage in pharmaceutical and biomedical contexts. Hence, many studies are now being carried out on the use of OFI mucilage as wound care material due to its high moisture retention, film-forming capacity, and anti-inflammatory properties [11]. When applied topically, it could create a protective, breathable barrier that maintains a moist wound environment, which is a key factor in accelerating re-epithelialization and tissue regeneration [52]. An in vitro wound-healing assay by Ammar et al. [74] showed that OFI mucilage accelerated dermal regeneration, highlighting its wound repair capability while reinforcing previous in vivo reports on the wound-healing capacities of OFI mucilage in rats [55]. Although mucilage is rarely extracted from the flowers of OFI, in vivo experiments using an excision wound model in rats have shown the ability of the mucilaginous flower extract to accelerate wound contraction and tissue remodeling [75]. The study attributed these activities to the presence of bioactive compounds, including flavonoids and polysaccharides, which contribute to antioxidant and antimicrobial activities. These compounds may also help to prevent secondary infections and oxidative damage at the wound site [76]. Mucilage-based dressings can be fabricated into gels, hydrogels, and thin films, sometimes reinforced with other natural polymers to improve mechanical strength [39]. Its non-cytotoxicity, ease of removal, and soothing effect make it an excellent alternative to conventional wound dressings, especially in burns, diabetic ulcers, and superficial cuts [55].

3.4.3. Environmental Applications

The OFI plant has long been recognized for its diverse environmental applications, including sustainable land management, erosion control, land reclamation, and agricultural development [77]. Gaviria-Bedoya et al. [78] further documented its multifunctional ecosystem roles, such as soil preservation, wildfire mitigation, ornamental use, boundary delineation, and carbon sequestration. Recent studies have expanded the potential applications of OFI mucilage, demonstrating its efficacy as a natural water flocculant, a bio-admixture in eco-friendly construction materials, and an agent for soil decontamination.

Water pollution from suspended solids, heavy metals, dyes, and other contaminants remains a global concern, particularly in developing regions where access to safe drinking water is limited [79]. Traditional chemical coagulants and flocculants such as alum, ferric chloride, and synthetic polyacrylamides have long been used in water treatment. However, their potential toxicity, non-biodegradability, and cost have driven the search for natural, eco-friendly alternatives [80]. In this context, mucilage from OFI has emerged as a promising natural flocculant. Rich in polysaccharides and functional groups like carboxyl and hydroxyl, OFI mucilage can interact with contaminants in water, promoting aggregation (flocculation) and sedimentation of suspended particles and metals [81]. Its biodegradability, low toxicity, and renewable availability make it a sustainable alternative for water purification [81]. It has been assessed for its role in turbidity and heavy metals removal. Turbidity is a key indicator of water quality caused by suspended solids such as silt, clay, organic matter, and microorganisms [82]. O. ficus-indica mucilage has demonstrated excellent performance across various water types, including river water, wastewater, and industrial effluents. For instance, it achieved 98% turbidity removal from oil sands process-affected water at an initial pH of 7 and 8 using 1500 mg/L within 60 min [83]. In another study, the mucilage removed 80.40% turbidity from river water at a dose of 35 mg/L and 82.9% from synthetic water at 20 mg/L [84]. Its effectiveness stems from its high molecular weight and viscous nature, which facilitates the bridging and binding of fine particles into larger, settleable flocs [85]. Moreover, the use of mucilage can significantly reduce the sludge volume produced, making downstream sludge handling more efficient [86].

For heavy metal removal, OFI mucilage has exhibited metal-binding properties, making it effective for the removal of toxic heavy metals such as lead (Pb²⁺), cadmium (Cd²⁺), arsenic (As³⁺), chromium (Cr⁶⁺), and copper (Cu²⁺) from contaminated water [80]. This metal removal capacity is primarily attributed to its uronic acid content and the presence of functional groups like −COOH and −OH, which can chelate or adsorb metal ions via electrostatic attraction, ion exchange, or complexation [87]. O. ficus-indica mucilage, either alone or in combination with other coagulants, has achieved metal removal efficiencies up to 100% in different study settings, positioning it as a viable biosorbent for heavy metal remediation. In one electrochemically assisted treatment system, it reached a copper removal efficiency of 100% in less than 5 min at a concentration of 30 mg/L and a pH of 7.8 [32]. In another study, it achieved over 90% removal of iron and manganese and over 60% for chromium and arsenic [81].

When compared to conventional coagulants like alum and ferric chloride, OFI mucilage required a higher dose but achieved comparable or better turbidity removal and a significantly higher arsenic removal [88]. According to a literature report, OFI mucilage lowers turbidity (83 vs. 95%) and color (72 vs. 80) removal compared to FeCl₃ [86]. Although this material has proven useful in water purification, the exact mechanism of the action of OFI mucilage may vary depending on water chemistry (pH, ionic strength), the type of contaminant, and the specific structure of the mucilage extract [89]. Nevertheless, this action has been generally attributed to adsorption and inter-particle bridging, facilitated by its polysaccharide nature and the presence of functional groups such as carboxyl, carbonyl, and hydroxyl [90]. The presence of divalent cations like calcium and magnesium ions in the mucilage has also been reported to enhance its coagulation properties [83].

As the construction industry moves toward more sustainable, low-carbon materials, bio-based additives have emerged as a viable alternative to traditional chemical admixtures. Among these, mucilage from OFI has shown promise as a natural bio-admixture capable of improving the mechanical, rheological, and durability properties of construction materials [91]. Mucilage from OFI, a hydrocolloid-rich biopolymer with adhesive, water-retentive, and ion-binding properties, has historically been used in lime-based mortars and is now being investigated for its applications in modern cementitious materials and soil stabilization techniques [92]. The mucilage acts through multiple mechanisms, including water retention, steric stabilization, rheological modification, and interaction with calcium ions with each contributing to the enhanced performance of construction composites [91].

In this regard, OFI mucilage has been traditionally used in lime mortars for its ability to enhance properties such as carbonation rate and mechanical strength [92]. It promotes the formation of the aragonite polymorph of calcium carbonate, which improves the mortar’s durability and strength [93]. The addition of mucilage to slaked lime formulations enhances the workability and smoothness of the fresh mortar, improving carbonation and crystallization processes and promoting the formation of amorphous calcite and aragonite [94,95]. It also increases mechanical performance, with reported improvements of up to 72% in compressive strength and 60% in flexural strength, while enhancing durability by reducing cracking [96]. These improvements are attributed to the formation of dense mineral–polysaccharide matrices, which refine the pore structure and limit microbial access, thereby reducing biodegradability and extending service life [97].

Furthermore, when used as an additive in cementitious materials, OFI mucilage improves consistency, strength, and water absorption [98]. Studies have shown that replacing up to 10% of the mixing water with mucilage can increase compressive strength by 9% after 180 days [99]. In Portland cement-based materials, OFI mucilage functions as a rheological modifier and internal curing agent [100]. Its high molecular weight and water retention allow for reduced shrinkage and autogenous cracking as well as improved workability and viscosity, aiding in self-compacting concrete [91].

Moreover, OFI mucilage has also been used to modify the engineering properties of lateritic soils, improving their suitability as sub-base materials for road construction by enhancing properties like unconfined compressive strength and reducing permeability [101]. The improved durability of these composites may be attributed to the formation of mineral–polysaccharide films that bind soil particles and limit water infiltration, thereby enhancing structural cohesion and weather resistance. Additionally, the polysaccharide matrix helps reduce biodegradability and extend the lifespan of stabilized materials, providing a sustainable alternative to conventional chemical stabilizers [91].

To facilitate a clearer understanding of the environmental potential of OFI mucilage,

Table 3. Comparative evaluation of environmental application of OFI mucilage.

Process Type	Efficiency	Mechanism	Advantages	Limitations	References
Turbidity removal	80–95%	Polymer bridging, charge neutralization	Renewable, biodegradable	Efficiency varies with ionic strength	[83,84,85]
Heavy metal removal	60–100% (Cu2+ > Fe2+ > Cr6+)	Chelation via −COOH and −OH groups	High selectivity	Sensitive to pH, competitive ions	[32,81,87]
Soil stabilization	Increased unconfined compressive strength, reduced permeability	Mineral-polysaccharide film formation	Improved durability	Requires drying uniformity	[101]
Lime mortar admixture	60–70% strength increase	Pore refinement, carbonation control	Eco-friendly binder	Scalability and consistency	[92,93,95]

provides a comparative overview of its reported process types, efficiencies, and mechanisms. Among the various applications, flocculation and turbidity removal are the most consistent, achieving 80–95% reduction across a wide pH range through charge neutralization and polymer bridging by carboxyl and hydroxyl functional groups [85]. The removal efficiencies of heavy metals are more variable, ranging from 60% to 100%, depending strongly on the type of metal ion, pH, and mucilage concentration [32]. In these systems, coordination between metal cations and galacturonic acid residues is the dominant mechanism [87]. In contrast, its role as a bio-admixture in soil stabilization and lime mortars relies primarily on physical film formation and matrix densification rather than ionic binding [91]. While these results highlight the multifunctionality of OFI mucilage, they also reveal a need for standardized testing protocols and toxicity assessments to ensure environmental safety and cross-study comparability.

3.5. Future Prospects and Research Gaps

The growing body of research on OFI mucilage has revealed its impressive physicochemical, biological, and functional attributes. While current applications span across the food, pharmaceutical, and environmental sectors, there remain several underexplored avenues where OFI mucilage could play a transformative role. These include innovative applications in nanotechnology, gut health, functional foods, and advanced biomedical systems. To fully harness this potential, interdisciplinary research, standardization of extraction techniques, and detailed mechanistic studies are essential.

O. ficus-indica mucilage possesses hydroxyl, carboxyl, and uronic acid groups, which have been demonstrated in other polysaccharide-rich biomaterials to reduce metal salts and stabilize metal nanoparticles [102,103]. These functional groups act as both reducing and capping agents, facilitating the green synthesis of silver, gold, or zinc nanoparticles [104]. Given mucilage’s viscosity, ionic interaction capacity, and reported antioxidant activity, it presents an ideal matrix for environmentally friendly nanoparticle synthesis. Future work could explore its role in tuning particle size, surface properties, and bioactivity for applications in catalysis, drug delivery, and antimicrobial coatings.

As a complex, non-digestible polysaccharide, OFI mucilage can pass through the upper gastrointestinal tract largely unchanged and reach the colon, where it can serve as a substrate for beneficial gut microbiota. Studies on similar plant-derived mucilages have shown their ability to selectively stimulate the growth of probiotic strains such as Lactobacillus and Bifidobacterium. For example, Molokhia leaf polysaccharide showed high prebiotic scores and increased short-chain fatty acids (SCFAs) in probiotic strains, indicating its potential to enhance gut health [105]. Similarly, flaxseed mucilage promotes the growth of probiotic bacteria and improves calcium absorption and bone health [106]. Previous studies on the prebiotic potential of OFI mucilage have revealed that the mucilage is fermented by gut bacteria, leading to the production of SCFAs like propionate and butyrate, which are beneficial for colon health and have anti-inflammatory properties [107]. However, more studies are required to fully harness its potential as a prebiotic. Additionally, the encapsulation efficiency of OFI mucilage previously demonstrated in other systems [47] suggests it may protect sensitive microbial strains from gastric acid, further enhancing its prebiotic potential. Notwithstanding, in vivo validation, gut microbiome interaction studies, and fermentation kinetics remain research gaps.

O. ficus-indica mucilage exhibits a gel-like consistency, high WHC, and a creamy mouthfeel, which are key attributes for fat mimetics in food systems [108]. It can simulate the texture, viscosity, and spreadability of fats in emulsions, dressings, and baked goods, while contributing significantly fewer calories. Unlike gelatin or other thermoreversible hydrocolloids, OFI mucilage’s fat-mimetic function arises primarily from its rheological and emulsifying properties rather than thermal reversibility [109]. Despite this, more research is needed to assess its sensory acceptability, thermal behavior during cooking, and interaction with other macronutrients in model food matrices.

One of the most promising areas for OFI mucilage lies in its potential as a natural polymer for drug encapsulation and delivery. With demonstrated high encapsulation efficiency, mucoadhesiveness, and controlled swelling [72], mucilage-based hydrogels and microparticles can offer sustained release of active pharmaceutical ingredients. These properties, combined with its biodegradability and low cytotoxicity [54], make it ideal for oral, transdermal, or mucosal delivery systems. Yet, the current literature lacks pharmacokinetic studies, release kinetics modeling, and biocompatibility testing in physiological environments, which are critical steps for advancing clinical translation.

O. ficus-indica mucilage contains co-extracted bioactive polyphenols and exhibits natural antimicrobial activity [110], which may be enhanced when used as a carrier for antibiotics or essential oils. Its film-forming and adhesive nature makes it ideal for topical gels, patches, or wound dressings, offering localized drug delivery with sustained release [61]. The mucilage matrix can be functionalized to release antimicrobial agents in response to pH changes, wound exudates, or microbial enzymes, adding responsive functionality to formulations. However, the synergistic effects with encapsulated antibiotics, microbial resistance modulation, and release profiles have yet to be thoroughly investigated.

Mucilage extracted from OFI holds significant promise in cosmetic and personal care formulations due to its multifunctional properties. As a natural emulsifying and stabilizing agent, it effectively maintains the stability of oil-in-water emulsions by increasing the viscosity of the continuous phase and promoting electrostatic repulsion between droplets, thereby reducing coalescence [111]. These rheological and interfacial properties make it particularly suitable for use in creams, lotions, and moisturizing formulations. Its documented wound-healing properties, including enhancement of re-epithelialization and dermal remodeling [74], support its inclusion in soothing and reparative skincare products such as ointments and healing balms. Furthermore, its hygroscopic and viscoelastic nature enables superior moisture retention, positioning it as a valuable ingredient in hydrating serums and moisturizers [55,112]. In addition, the mucilage exhibits notable antioxidant and antibacterial activities, which confer anti-aging effects and enhance the shelf-life and microbial stability of cosmetic formulations, enabling its use as a natural preservative and active compound in a variety of personal care products [75]. A summary of the prospects as it relates to the research gaps and application is presented in

Table 4. Summary of the Future prospects and research gaps in the applications of O. ficus indica mucilage.

Application Area	Scientific Basis	Research Gaps	Potential Impact
Metal nanoparticle synthesis	Reducing and capping properties via hydroxyl/carboxyl groups	Optimization of synthesis conditions; nanoparticle characterization	Eco-friendly nanomaterials
Prebiotic functional ingredient	Non-digestible polysaccharides support gut microbiota; good encapsulation of probiotics	In vivo studies on fermentation, microbiome modulation	Gut health, functional foods
Fat replacer in foods	High viscosity, gel-forming, and creamy texture	Sensory evaluation; compatibility with food matrices	Low-calorie food formulations
Drug delivery systems	High encapsulation efficiency, mucoadhesion, and biodegradability	Pharmacokinetics; release modeling; biocompatibility assays	Targeted, sustained drug delivery
Tissue engineering scaffolds	Biocompatible, porous, moisture-retaining, supports cell growth	In vivo studies; mechanical property optimization	Regenerative medicine
Antimicrobial/antioxidant carriers	Natural antimicrobial and antioxidant activity; film-forming capability	Controlled release profiling; synergy with antibiotics	Topical agents, active dressings
Cosmetics and personal care	Emulsifying, moisturizing, antimicrobial, antioxidant properties	Long-term skin compatibility studies; stability testing	Natural ingredient in personal care

.

3.6. Integration with Circular Economy

While the large-scale production of OFI mucilage offers exciting potential for diverse applications, an important yet under-discussed consequence is the generation of significant biomass waste, particularly from dethorning and peeling processes [113]. For example, it has been reported that OFI cladode dethorning alone generates up to 40,000 tons of waste annually in Mexico City [114]. Since mucilage is primarily extracted from the inner medulla of the cladode, the outer peel and thorny epidermis are often discarded, resulting in large volumes of underutilized organic waste. However, recent studies have explored innovative valorization pathways to integrate this waste into circular economy frameworks. Marin-Bustamante et al. [113] demonstrated that the fibrous waste from pruning and dethorning can be successfully converted into biodegradable paper products with mechanical properties comparable to traditional wood and non-wood pulps, including tensile strength, stretch, porosity, and burst index. Additionally, alternative mucilage extraction from peel waste has been investigated, yielding higher quantities of mucilage compared to the medulla, albeit with lower concentrations of phenolics and betalains, which may limit its bioactive potential [24]. These findings suggest a strong opportunity for resource recovery and full-plant utilization, aligning with the principles of waste minimization and material circularity.

To truly realize the circular economy potential of OFI mucilage production, industrial partnerships will be essential. Collaborations between research institutions, agricultural cooperatives, and private sector companies can help bridge the gap between laboratory-scale valorization and commercial deployment. Such partnerships can facilitate the development of scalable biorefinery models, whereby by-products such as cladode peels, thorn residues, or press cakes are repurposed into value-added products like compost, bio-packaging materials, functional fibers, or secondary mucilage streams. Moreover, industry engagement is crucial for process optimization, supply chain integration, and investment in sustainable technologies such as low-energy drying or green extraction systems. With the right partnerships, OFI mucilage production can move beyond isolated innovation and become part of a sustainable, closed-loop bioeconomy, particularly in arid and semi-arid regions where the plant is already abundant.

To advance from conceptual sustainability toward measurable circularity, future studies should incorporate quantitative environmental indicators such as energy input, solvent recovery efficiency, and overall carbon footprint of the extraction and drying processes. Integrating life-cycle assessment methodologies would provide insights into the comparative environmental benefits of OFI mucilage relative to synthetic or other biopolymer alternatives. For instance, assessing process energy demand (in kWh/kg of mucilage) and solvent reuse potential could inform the design of low-impact biorefineries. Such metrics will be essential for validating the circularity and environmental performance of industrial-scale OFI mucilage production systems.

3.7. Challenges and Potential Solutions for the Application of O. ficus-indica Mucilage

Despite the promising multifunctional applications of OFI mucilage across diverse sectors, several challenges and limitations may hinder its widespread adoption and industrial scalability. These challenges stem primarily from variability in composition, extraction complexity, and inconsistencies in functional performance, all of which necessitate further research and technological optimization (

Table 5. Summary of Challenges in the application of O. ficus-indica mucilage.

Challenges	Description	Implication	References
Variability in Composition	Affected by cultivar, environment, and season	Limits standardization and reproducibility of product functionality	[65,115]
Extraction Challenges	Influenced by extraction method, water ratio, temperature, drying technique	Affects yield, purity, and scalability	[33,116]
Environmental Impact of Extraction	Use of solvents in traditional methods	Necessitates greener extraction approaches	[23,71]
Functional Inconsistencies	Differences in viscosity, emulsification, protein content	Reduces performance predictability in food and cosmetic formulations	[43,117]
Cost and Scalability	High production cost, need for specialized equipment	Limits industrial application; requires optimization for economic viability	[23,116]
Competition with Synthetic Polymers	Synthetic polymers offer more consistency and engineered properties	Challenges adoption unless mucilage is functionally enhanced	[108]

; Figure 5).

The physicochemical composition of OFI mucilage is highly influenced by environmental conditions, seasonal fluctuations, and genetic diversity among cultivars [35,116]. These variations directly affect key properties, such as viscosity, emulsifying capacity, and bioactivity, resulting in inconsistent performance across batches. For example, the Algerian cultivar has been shown to produce mucilage with markedly different rheological and emulsifying properties compared to other OFI varieties [66,109]. This heterogeneity presents a major barrier to standardization and regulatory approval, particularly in food, pharmaceutical, and cosmetic formulations. To address this, future work should prioritize the development of standardized mucilage characterization protocols, alongside advanced analytical methods like metabolomics and rheological fingerprinting to define quality benchmarks. Moreover, targeted breeding and cultivar selection programs could help identify genotypes with stable mucilage profiles, thereby reducing variability and enhancing industrial reliability.

The extraction of mucilage from OFI cladodes is also a major concern in its large scale application. It is a multi-step process that requires careful control of parameters such as water-to-biomass ratio, temperature, and drying methods, as these variables significantly influence both yield and mucilage quality [117]. While newer, eco-friendly techniques such as ultrasound- and microwave-assisted extraction show promise, their effects on mucilage structure and functionality are not yet fully understood [33]. Furthermore, traditional solvent-based extraction methods raise concerns about environmental sustainability and solvent residues [71]. To address these challenges, research should focus on process optimization using statistical and machine learning models to define optimal extraction conditions and the integration of enzyme-assisted or purely water-based techniques to replace solvents. Hybrid approaches that combine mild pre-treatment with ultrasound or microwave energy may improve both yield and functionality while reducing environmental impact. In addition, pilot-scale validation and life-cycle assessments will be essential to ensure that these greener methods are effective in preserving mucilage properties and also economically viable and scalable for industrial production [23].

Although the non-Newtonian, shear-thinning behavior of OFI mucilage can be advantageous in applications such as coatings or suspensions, it can pose challenges in systems that require stable viscosity profiles [18]. Additionally, variability in phytochemical contents affects key functionalities such as foaming and emulsification, limiting the mucilage’s use as a consistent food additive [117]. For instance, in products like mayonnaise, its ability to replace egg yolk or oil is highly dependent on the emulsifying efficiency, which varies across cultivars and extraction methods [43]. Similarly, in pharmaceutical and cosmetic formulations, the presence of bioactive compounds and polysaccharides of varying molecular weights can enhance product functionality, yet these same variations complicate formulation reproducibility and precise dosing [110]. Interestingly, fractionation and purification strategies to isolate polysaccharide fractions with consistent molecular weights and functionality are currently being explored as potential solutions [30,74]. Future studies should further explore blending OFI mucilage with other hydrocolloids such as alginate, pectin, or chitosan, which could stabilize viscosity and improve emulsifying properties. Additionally, selective breeding and cultivar standardization, combined with predictive formulation models, may provide a pathway to achieving reproducible performance across both food and biomedical applications.

The cost of extraction, processing, and formulation remains a critical bottleneck for the commercial utilization of OFI mucilage. The requirement for specialized equipment, combined with the high time and energy demands of drying and purification, renders large-scale production economically challenging [23,117]. Unlike other crops, the cultivation of OFI itself is inherently sustainable, requiring low inputs; thus, the major barriers to commercialization lie in the post-harvest processing chain rather than in agricultural practices. Addressing these challenges will require the development of cost-effective and energy-efficient technologies, such as solar-assisted drying, spray-freeze hybrid systems, or membrane-based purification to reduce operating costs. In addition, integrating mucilage recovery with other OFI valorization pathways, such as livestock feed and paper production, could improve the overall economics of processing by creating multi-product value chains.

One of the most significant barriers to the industrial adoption of OFI mucilage is its competition with well-established synthetic polymers such as polyacrylamides, polyethylene glycols, polyvinyl alcohols, and synthetic emulsifiers. These materials provide high purity, batch-to-batch consistency, tailored molecular weights, and engineered functionalities that are challenging for natural polymers to replicate. By comparison, OFI mucilage, despite being biodegradable, renewable, and functionally versatile, faces limitations such as variability in composition. Furthermore, synthetic polymers have the advantage of decades of industrial optimization, regulatory approvals, and well-established supply chains, making them widely available and cost-competitive. To bridge this gap, technological innovations and targeted modifications are required. Strategies such as chemical or enzymatic crosslinking, graft copolymerization, or blending with other natural and synthetic polymers can significantly enhance the stability, mechanical performance, and thermal resistance of OFI mucilage. The incorporation of mucilage into nanocomposite systems also offers opportunities to tailor its functionality for high-performance applications. On the industrial side, scaling up optimized extraction protocols, supported by public–private partnerships and favorable regulatory frameworks, could reduce costs and improve competitiveness. Additionally, market positioning of OFI mucilage in niche applications where biodegradability, biocompatibility, or sustainability are critical may provide a practical entry point before expanding into broader markets. Together, these approaches will be essential for OFI mucilage to establish itself as a viable alternative to entrenched synthetic polymers.

4. Conclusions

Mucilage derived from OFI is distinguished as a multifunctional, plant-based biopolymer, exhibiting a range of physicochemical properties that facilitate its application across various industries. Its established roles as a thickening agent, gelling agent, and encapsulant within the food sector are complemented by its emerging applications in drug delivery systems, wound care, tissue engineering, and environmental remediation, thereby underscoring the necessity for enhanced scientific and industrial exploration of OFI mucilage. Moreover, its potential integration into cosmetic formulations, prebiotic functional foods, fat-reduced products, and green construction materials further highlights its untapped versatility and alignment with sustainable development goals.

Nevertheless, despite its clear potential, the industrial translation of OFI mucilage remains limited. Variability in its composition, lack of standardized extraction protocols, and incomplete mechanistic understanding of its biofunctional properties represent key barriers to commercialization. To overcome these challenges, a coordinated interdisciplinary approach is urgently needed, one that brings together plant scientists, materials chemists, process engineers, food technologists, and biomedical researchers. Furthermore, collaboration with industry stakeholders will be critical for the development of scalable processing technologies, regulatory frameworks, and value-added applications.

In summary, OFI mucilage is not merely a traditional natural material; it is a next-generation biomaterial waiting to be fully realized. Unlocking its full potential requires investment in scientific innovation, cross-sector collaboration, and sustainable commercialization strategies that can transform it from a promising resource into a cornerstone of the bio-based economy.