Biotechnological Potential of Carrageenan Extracted from Kappaphycus alvarezii: A Systematic Review of Industrial Applications and Sustainable Innovations

Abstract

Kappaphycus alvarezii is an important source of carrageenan, a polysaccharide widely utilized for its gelling and stabilizing properties. However, understanding advancements in its application is crucial for broadening its biotechnological uses and promoting sustainable practices. This study aimed to conduct a systematic review of the applications of carrageenan from K. alvarezii, following PRISMA guidelines. A search was conducted in the CAPES Journals Portal and Scopus databases from 2010 to 2025, using the descriptors “Kappaphycus alvarezii” and “carrageenan.” Out of 491 analyzed articles, 38 met the inclusion criteria, categorized into health/medicine (n = 11), human food (n = 10), general industry (n = 8), animal nutrition (n = 6), and agriculture (n = 3). The findings reveal various applications, including scaffolds, antimicrobial agents, encapsulants, and wound dressings in health/medicine; edible films and food additives in human food; biomaterials and bioproducts, as well as applications in biorefinery in general industry; applications in aquaculture and livestock in animal nutrition; and as a defense inducer or biostimulant in agriculture. Despite a limited number of articles specifically addressing the direct applications of carrageenan from K. alvarezii, its uses are extensive across various industries.

1. Introduction

Marine ecosystems represent a remarkable and vast source of unexplored and valuable materials, with seaweeds serving as an essential biological resource in the global economy [1]. Red algae (Rhodophyta) are particularly significant in this context, accounting for over 60% of the world’s total cultivated alga species and exhibiting a high content of polysaccharides, averaging 40–50% of dry weight biomass [2,3,4]. Among the main polymeric carbohydrates commercially exploited from marine organisms—which include alginates (derived from brown seaweeds) and agar (derived from red seaweeds)—carrageenans are the most prominent sulfated galactans [5].

These high molecular weight polysaccharides represent a significant portion of the marine algal compound market and hold immense economic potential across various industries [6,7,8]. Global carrageenan production is predominantly achieved through aquaculture-based seaweed farming, with species belonging to the genera Eucheuma and Kappaphycus contributing over 90% of the total output. Among these, Kappaphycus alvarezii (Figure 1A) is the most commercially valuable Rhodophyta, making it the world’s most important carrageenophyte [9,10,11]. This macroalga is primarily cultivated in Asian countries, such as Indonesia, the Philippines, Vietnam, and Malaysia, as well as in subtropical regions [12].

K. alvarezii is a meaningful source of carrageenan due to its rapid growth rates, with harvest cycles of just 45–60 days, and high polysaccharide yields [13]. On average, the biomass of K. alvarezii consists of 50.8% carbohydrates, 3.3% proteins, and 3.3% lipids, along with sulfate groups and ash [3,11]. Carrageenan is defined as a class of hydrophilic, sulfated linear polysaccharides found in red seaweed’s cell walls [11]. Its structure comprises repetitive disaccharide units (carrabiose) formed by alternating residues of 3-linked β-D-galactopyranose and 4-linked α-D-galactopyranose or 3,6-anhydro-α-D-galactopyranose, linked by an α-1, 3 glycosidic bond [14,15].

The three major commercial types of carrageenan (Figure 1B), namely κ-(kappa), ι-(iota), and λ-(lambda), can be distinguished primarily by their number and position of ester sulfate groups and the presence of the 3,6-anhydro bridge [1]. The monosaccharide 3,6-anhydrogalactose is crucial in the carrageenan’s chemical structure, as it drives the formation of thermoreversible gels, a characteristic essential for industrial applications [5,16]. Carrageenan extracted from K. alvarezii is predominantly κ-carrageenan, which contains only one sulfate group per repeating unit (approximately 22% w/w) and exhibits the highest gelling capacity, resulting in opaque, brittle gels [17,18].

Historically, the primary destination for carrageenan has been the food industry, accounting for 70–80% of total global consumption [19,20,21]. It is widely used as a hydrocolloid to thicken, stabilize, and gel products such as dairy, preventing phase separation in yogurt, jellies, confectionery, and processed meat products, thereby improving texture and moisture retention [1,22,23]. However, its applications have been expanded beyond the food sector into high-value areas [8,11,24]. For instance, in the pharmaceutical and biomedical industries, carrageenan is valued for its biocompatibility, high molecular weight, and gelling capacity, making it suitable for use as an excipient in pills, drug delivery systems, and tissue engineering [18,25]. Other applications include cosmetic formulations (creams, toothpaste, and shampoos) [20,21,26] and the development of fertilizers and agricultural biostimulants, such as the liquid extract known as K-sap [27,28].

Given the diverse applications of carrageenan, it is important to highlight those derived from K. alvarezii as a primary source. The carrageenan extracted from this macroalga possesses unique properties that distinguish it from other sources, such as Chondrus crispus. K. alvarezii produces a specific type of carrageenan that exhibits superior gelling and stabilizing capabilities, making it particularly valuable for food and pharmaceutical applications [11,29]. Additionally, its faster growth rate and higher yield in aquaculture settings allow for more sustainable harvesting practices. These attributes not only enhance its commercial viability but also emphasize the ecological benefits of utilizing K. alvarezii over other alternatives [1,29]. Thus, this study aims to conduct a systematic literature review of scientific articles published between 2010 and 2025, exploring the diverse uses of carrageenan extracted exclusively from K. alvarezii.

2. Materials and Methods

2.1. Study Design

The present systematic review was carried out following the PRISMA criteria (Pre-ferred Reporting Items for Systematic Reviews and Meta-Analyses—https://www.prisma-statement.org/prisma-2020; Supplementary File (accessed on 26 January 2026); [30]), by searching for scientific articles in the CAPES Journals Portal database, created by the Coordination of Improvement of Higher Education Personnel (CAPES, in Portuguese) of the Ministry of Education in Brazil. CAPES Journals Portal was utilized due to its extensive collection of over 390 databases and 39,000 scientific journals [31]. Additionally, a second database, Scopus, was utilized to expand the search.

The descriptors used in the search included the scientific name of the macroalga, “Kappaphycus alvarezii,” along with the research focus term, “carrageenan.” The filters applied comprised articles published between 2010 and 2025, exclusively in English and peer-reviewed. The search encompassed titles, abstracts, and keywords.

2.2. Quality Assessment

Two reviewers (L.V.C. and A.R.S.) independently performed the literature review, reducing any influence of bias in the selection of articles. A third analysis was conducted to identify any potential discrepancies. For this purpose, a reviewer (A.N.) independently examined the tables provided by the initial reviewers to compare the inclusion and exclusion criteria, as well as the categorization of sectors. After this meticulous process, the stage was concluded.

Only peer-reviewed articles within the established period (2010–2025) were selected. The mapping and evaluation of the articles were conducted in two phases: from 14 July to 29 August 2025, and then from 11 December to 17, 2025, with the search expanded to include the current year.

2.3. Data Extraction

Data were fully extracted from the CAPES Journals Portal (n = 227) and Scopus (n = 264) databases for further analysis. Data were tabulated into a Microsoft Excel^® data sheet (xlsx), inserting the title of the paper, the year of publication, the area involved in the study, and the aim of the study. For those articles added based on the inclusion criteria, a comprehensive analysis was conducted, including data on the journal name in which the manuscript was published, category (sector) and subcategory, methodology, collection site of the macroalga for carrageenan extraction, obtained results, and conclusions.

2.4. Inclusion/Exclusion Criteria

On the platform, only peer-reviewed scientific articles were selected (n = 491) and compiled into a Microsoft Excel^® data sheet (.xlsx). Initially, it was found that 113 articles were duplicated among the databases; therefore, only one of each duplicate was retained. Additionally, one article was not published in English. From the remaining 377 manuscripts, several were excluded based on established criteria, specifically: literature review articles (n = 6), characterization and methodological articles (n = 122), articles where K. alvarezii was mentioned in the text without addressing the topic (n = 32), articles with undefined carrageenan origin (n = 23), and articles that discussed subjects outside the scope (n = 156).

The inclusion criteria considered articles focused on the development of products using carrageenan extracted from K. alvarezii. Consequently, a total of 38 articles were selected for the manuscript. These articles were categorized into five groups: health/medicine (n = 11), human food (n = 10), general industry (n = 8), animal nutrition (n = 6), and agriculture (n = 3) (Figure 2).

3. Results and Discussion

3.1. Study Selection and Characteristics

Among the 38 articles selected based on the established inclusion criteria, the year 2024 exhibited the highest number of publications (n = 6), followed by 2018, 2023, and 2025, each with five publications. The years 2013, 2020, and 2021 recorded four publications each, while 2019 and 2022 had two publications each. Additionally, 2017 contributed one publication. Interestingly, no publications were identified for the years 2010, 2011, 2012, 2014, 2015, and 2016 (Figure 3).

The journal with the highest number of publications was the International Journal of Biological Macromolecules, which featured six articles. This was followed by the Journal of Applied Phycology, which contributed a total of four articles, and the IOP Conference Series: Earth and Environmental Science, with two articles. The remaining journals, e.g., International Journal of Polymer Science, Journal of Biomaterials Applications, Journal of Coastal Research, The Journal of Supercritical Fluids, The Open Conference Proceedings Journal, Scientific Reports, Iraqi Journal of Pharmaceutical Sciences, Jurnal Pengolahan Hasil Perikanan Indonesia, IOP Conference Series: Materials Science and Engineering, Asia-Pacific Journal of Science and Technology, Materials Research Express, ASM Science Journal, Industrial Crops and Products, Pigment & Resin Technology, Systems Microbiology and Biomanufacturing, Biomass Conversion and Biorefinery, Bioresource Technology Reports, Polysaccharides, Engineering Journal, Aquaculture, Indonesian Journal of Marine Sciences, Journal of Fish Health, Israeli Journal of Aquaculture, Journal of the Science of Food and Agriculture, Algal Research, Journal Of Critical Reviews, published one article each.

From the publications, it was observed that 30 articles described the cultivation and collection locations of K. alvarezii for carrageenan extraction. However, two studies did not specify these details [32,33], and another one did not report the source of the macroalga, although the authors are based in Rio de Janeiro state (south-eastern Brazil), where K. alvarezii has been cultivated [34]. Five articles, while specifying the location of the experiments and analyses, used commercially available carrageenan and describe it as derived from K. alvarezii [35,36,37,38,39]. Another manuscript mentions that the commercial carrageenan was provided by a company in Brazil, South America [40]. Among the 30 manuscripts, 26 are from Asian countries: 10 from Indonesia [10,41,42,43,44,45,46,47,48,49], nine from India [8,18,19,20,27,28,50,51,52] and six from Malaysia [25,53,54,55,56,57]. Lastly, three articles document the biomass being sourced from South America, specifically from collections in Brazil [17,58,59] (Figure 4).

Among the 38 selected articles, significant applications of carrageenan extracted from K. alvarezii were identified across multiple industrial sectors: health/medicine (n = 11), human food (n = 10), general industry (n = 8), animal nutrition (n = 6), and agriculture (n = 3).

3.2. Health/Medicine

Eleven studies were identified in the health/medicine sector (

Table 1. Articles published in the CAPES Periodical Portal and Scopus database (2010–2025) on the use of carrageenan extracted from the seaweed Kappaphycus alvarezii in the areas of Health/Medicine (n = 11).

Area	Nº	Target Effect	Matrix Used	Results	References
Scaffolds	1	Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) porous 3D scaffolds with carrageenan to assess stability and cellular acceptability	PHBV and k-carrageenan of K. alvarezii	The 4% carrageenan-infused scaffold emerged as the best candidate for tissue engineering applications and 3D cell culture models, balancing degradation kinetics with sustained structural support	Johari et al. [25]
	2	Enhanced wound healing, including improved collagen deposition, neovascularization, and reduced wound size	Carrageenan hydrogel encapsulating mesenchymal stromal cells (eCH+MSC)	The eCH+MSC treatment showed better wound closure, increased collagen deposition, and higher vessel density, indicating greater healing efficacy	Rode et al. [17]
	3	Molluscan nacre and using natural polymers, to evaluate its structure, composition, and potential biomedical applications	k-carrageenan of K. alvarezii, collagen of Sepia lycidas, and chitosan of shrimp shell	The scaffolds presented broad potential for tissue engineering applications, including 3D cell culture models for the production of edible meat, tissues, and organs	Vignesh et al. [18]
	4	Aerogels are produced from high-purity α-carrageenan	Commercial carrageenan (CC) and high-purity carrageenan (HP) of K. alvarezii	The use of high-purity carrageenan results in materials exhibiting superior firmness and greater surface area compared to those produced via commercial carrageenan methods or cryogels	Rudke et al. [59]
Antimicrobial	1	The anticytotoxic activity and oral antibacterial activity of crude κ-carrageenan powder, ι-carrageenan, and kappa seaweed	Crude powder of κ-carrageenan, ι-carrageenan, kappa seaweed of K. alvarezii and Eucheuma spinosum and human cells (HepG2, Caco-2) cells	These types of carrageenan and the crude powder of kappa seaweed were non-toxic to HepG2 and Caco-2 cells	Ariffin et al. [53]
	2	The antiviral activity against tobacco mosaic virus (TMV)	Derivatives of κ- and κ/β-carrageenans, and Nicotiana tabacum L. leaves (Samsun strain)	High molecular weight carrageenan derivatives proved generally more effective and retained antiviral capacity against tobacco mosaic virus	Kalitnik et al. [35]
	3	κ-Carrageenan exhibits significant antibacterial and anti-biofilm properties wound associated bacteria	κ-Carrageenan from K. alvareziin nutrient broth and red blood cells (RBCs)	κ-Carrageenan attacks and eliminate multidrug-resistant wound-associated bacteria by disrupting cellular membranes, inhibiting biofilm formation, and inducing oxidative stress, while demonstrating no cytotoxicity toward human red blood cells	Ramachandran et al. [51]
Blinding agent	1	Carrageenan from K. alvarezii demonstrated its potential as a binder for metformin tablets	Metformin HCl, carrageenan extracted from K alvarezii, and carbopol	Carrageenan demonstrated its potential as a binder for metformin tablets, suggesting the need for further optimization to enhance degradation performance	Kurniawan et al. [48]
Therapeutic agent	2	In vivo antioxidant potential of native carrageenan against alloxan-induced oxidative stress in Wistar albino rats	Carrageenan from K. alvarezii, commercial carrageenan and Wistar albino rats	Native carrageenan from K. alvarezii exhibits significant antioxidant, anti-inflammatory, and anticoagulant properties, positioning it as a promising therapeutic agent for oxidative stress and diabetes-related complications, with superior pharmacological activities	Sanjivkumar et al. [36]
Encapsulating agent	1	Potential of carrageenan as a material for hard capsules through hydrolysis of marine fungi, demonstrating its characteristics	Carrageenan from K. alvarezii and marine fungus Enhalus sp.	Carrageenan was successfully extracted via marine fungi hydrolysis, showing strong potential for hard capsules. Semi-refined carrageenan displayed promising physicochemical properties and suitable disintegration times	Tarman et al. [60]
Wound dressing	1	Carrageenan, combined with polyvinylpyrrolidone and glycerol in the development of biodegradable wound dressing applications	Carrageenan from K. alvarezii, polyvinylpyrrolidone (PVP), and glycerol (GLY), methicillin-resistant Staphylococcus aureus, E. coli, and Wistar rats	The films demonstrated excellent absorption, transparency, mechanical strength, antibacterial activity, and biocompatibility, making them a promising solution for advanced wound treatment applications	Amruth et al. [38]

), with publications from 2013 (n = 2), as well as 2017, 2018, 2019, and 2020 (n = 1 each), in 2024 (n = 3) and 2025 (n = 2). Among these, notable applications of carrageenan included its use as a scaffold (n = 4), as an antimicrobial agent (n = 3), as a binding agent (n = 1), as a therapeutic agent (n = 1), as an encapsulating agent (n = 1), and for wound healing (n = 1).

Starting with studies that focused on the use of carrageenan as a scaffold, Johari et al. [25] evaluated carrageenan as an alternative material in a three-dimensional porous framework made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Carrageenan concentrations ranging from 2% to 10% (w/v) exhibited alkaline pH values fluctuating from 9.00 ± 0.08 to 9.20 ± 0.04 and viscosities between 0.005 and 0.8 Pa·s. The polysaccharide at 2% concentration was optimal for good permeability throughout the porous structure (5.49 ± 1.22% w/w). Regarding degradation kinetics, the 6% carrageenan scaffold showed the greatest mass loss, while the 2% scaffold had the slowest degradation rate (0.011 ± 1.66 mg/day). The 4% carrageenan scaffold provided balanced structural support and moderate degradation over 14 days, making it most suitable for tissue engineering and 3D cell culture. Overall, carrageenan enhances scaffold functionality as an innovative material for tissue engineering applications.

In a study by Rode et al. [17], semi-refined carrageenan (eCH), commercial carrageenan (cCH), and microencapsulated skin-derived mesenchymal stem cells (SD-MSCs) within K. alvarezii carrageenan hydrogel scaffolds (eCH+MSC) were compared. The results showed that carrageenan hydrogels loaded with multipotent stromal cells derived from human skin enhanced wound healing properties, including reduced inflammation, accelerated wound closure, and improved extracellular matrix deposition. In vivo studies indicated that eCH+MSC treatment significantly reduced wound size by day 3, with increased collagen deposition and vascularization observed on days 7 and 14, despite a mild inflammatory response. Human cells were effectively delivered to wound sites, and the hydrogel-maintained cell viability for at least eight days in culture. Overall, carrageenan, particularly in its extracted form, demonstrates great potential in tissue engineering due to its biocompatibility, support for SD-MSC growth, favorable porous structure, and cost-effectiveness as a cell delivery system for wound healing.

Vignesh et al. [18] investigated bioactive marine materials for tissue engineering scaffolds. They found that carrageenan derived from K. alvarezii yielded 36.5% (w/w), while chitosan from shrimp shells yielded about 20%, and collagen from Sepia lycidas skin yielded roughly 2.5% (w/w). Characterization of composite collagen-chitosan-carrageenan scaffolds revealed thermal stability and a porous structure with diameters ranging from 19 to 44 µm, thereby enhancing the protein absorption capacity to 2000 µg within approximately 120 h. The scaffolds rapidly swelled, reaching 94% saturation in 24 h and full saturation by 96 h, primarily due to the carrageenan content. Degradation rates in Minimum Essential Media (MEM) were about 24% and 56% after 24 h and 96 h, respectively, remaining stable for up to two weeks. Importantly, fish muscle cells (Trachinotus blochii) cultured on the scaffolds exhibited over 90% viability after 120 h, promoting muscle fiber formation by day 5, confirming their biocompatibility. These marine biomaterial scaffolds demonstrate significant potential for tissue engineering, including in 3D cell culture models for the production of edible meat, tissue, and organs.

Finally, Rudke et al. [59] identified that high-purity κ-carrageenan, when transformed into aerogels through supercritical CO₂ drying, produces materials with enhanced mechanical performance and distinct characteristics, making them suitable for support structures or controlled release systems. In the study, a comparative analysis was conducted on the properties of aerogels produced from commercial carrageenan (CC) and high-purity carrageenan obtained through sequential high-pressure extractions (HP). The influence of the drying method (lyophilization versus supercritical CO₂ drying) on the resulting material structure was also examined. Aerogels prepared from HP demonstrated greater firmness, achieving values up to 254 N, which markedly exceeded those of CC aerogels (206 N) and both cryogel variants (32.7 N for HP and 10.3 N for CC). The HP carrageenan imparted a higher water absorption capacity to the aerogels relative to the CC counterpart. Aerogels derived from HP carrageenan presented a larger specific surface area (105.40 m²/g) compared to those from CC (88.90 m²/g). Samples based on HP exhibited more pronounced volumetric shrinkage (96%) than CC samples. HP aerogels displayed higher envelope density (0.008 g/cm³) and slightly lower porosity (99.52%) than CC aerogels (envelope density of 0.005 g/cm³ and porosity of 99.74%). In general, cryogels showed higher porosity levels than aerogels. The purity and molecular weight of the carrageenan samples (HP and CC) affected both the viscosity behavior and the characteristics of the porous materials. The HP carrageenan, characterized by lower molecular mass (475.05 kDa) and greater purity, exhibited decreased viscosity and a reduced thermal transition temperature (194 °C) in comparison to CC (molecular mass of 35,240 kDa and thermal transition of 243.74 °C).

Regarding antimicrobial action, the first study by Ariffin et al. [53] evaluated the anticytotoxic and antibacterial properties of crude κ-carrageenan powder, ι-carrageenan, and kappa seaweed powder against oral bacteria. None of the three types of carrageenan (κ-carrageenan, ι-carrageenan, and crude kappa seaweed powder) exhibited an IC₅₀ value in human hepatocellular carcinoma (HepG2) and human colorectal adenocarcinoma epithelial (Caco-2) cells within the tested concentration range of 31.25–2000 µg/mL, as assessed by the MTT assay. The study also found that carrageenan did not inhibit the growth of oral bacteria. Accordingly, the authors concluded that ι-carrageenan, κ-carrageenan, and crude kappa seaweed powder do not function as anti-oral bacterial agents.

Kalitnik et al. [35] examined the effects of low molecular weight (LMW) derivatives from various carrageenan types, generated through chemical and enzymatic depolymerization methods, on tobacco mosaic virus (TMV) infection in detached tobacco leaves to assess their comparative antiviral efficacy. All tested carrageenan samples, encompassing native polymers and their LMW derivatives, reduced the number of local lesions on Nicotiana tabacum L. leaves, achieving inhibition rates of 30–88% relative to control leaves. Native high molecular weight (HMW) polymers (250, 390, and 400 kDa) displayed the highest antiviral activity, with 75–88% inhibition of local necrosis development. The sulfate content and constituent sugars of the algal polysaccharides represent key parameters influencing their antiviral performance, varying by carrageenan type; highly sulfated κ-carrageenan and its LMW derivatives exhibited greater antiviral activity than κ/β-carrageenan and its oligosaccharides.

In the last study of this subcategory, Ramachandran et al. [51] demonstrated that κ-carrageenan extracted from K. alvarezii exhibits significant antibacterial and antibiofilm activity against multidrug-resistant (MDR) bacteria associated with wounds. The study focused on elucidating the mechanism of action and effectiveness against common wound pathogens. The κ-carrageenan displayed strong antibacterial effects against S. aureus, E. coli, P. aeruginosa, P. vulgaris, and V. parahaemolyticus. At a concentration of 100 µg/mL, it produced markedly larger zones of inhibition and substantially reduced bacterial counts compared to lower concentrations. Optical density measurements of treated bacteria remained low for 12 h at 100 µg/mL, indicating sustained inhibitory activity. At the same concentration, κ-carrageenan showed notable antibiofilm effects, achieving inhibition percentages ranging from 70.6% to 85.3% across the tested pathogens. Intracellular leakage of proteins and nucleic acids confirmed that 100 µg/mL of κ-carrageenan increased membrane permeability, resulting in cell death. Fluorescence microscopy revealed a time-dependent increase in propidium iodide-stained cells, further evidencing bacterial cell death. At 100 µg/mL, κ-carrageenan exhibited no cytotoxicity toward human erythrocytes, thereby supporting its antibacterial and antibiofilm properties without harming host cells.

As a binding agent, Kurniawan et al. [48] characterized the binding properties of carrageenan extracted from K. alvarezii and evaluated its effectiveness as a tablet binder using metformin as a model drug. Kurniawan et al. [48] The carrageenan exhibited a compressibility index of 21.9% and demonstrated a high swelling index of 240% at pH 1.2. Granules prepared with carrageenan showed an angle of repose of 30.48° and a flow rate of 5 g/s. Viscosity measurements indicated values of 45,922.85 cps at 75 °C and 53,690 cps at 50 °C. Scanning electron microscopy (SEM) revealed irregular particle morphology, while Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of sulfate ester, 3,6-anhydrogalactose, and galactose-4-sulfate groups, consistent with κ-carrageenan. Metformin tablets formulated with carrageenan as the binder met the required physical specifications, including hardness, friability, weight uniformity, and size uniformity. However, notable differences were observed in granule flow rate, tablet disintegration time, and dissolution profiles compared to those prepared with Carbopol. Despite these variations, the findings indicate that carrageenan can serve effectively as a suitable binder for metformin tablets.

As a therapeutic agent, Sanjivkumar et al. [36] examined the biological properties and antioxidant potential of native carrageenan extracted from K. alvarezii, comparing it with commercial carrageenan under controlled laboratory conditions using Wistar albino rats. The findings showed that both native and commercial carrageenans increased the levels of antioxidant enzymes, including catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione S-transferase (GST), and reduced glutathione (GSH), as well as ascorbic acid content in the kidney tissues of alloxan-induced diabetic rats, while reducing lipid peroxidation (LPO). The native carrageenan displayed superior anti-inflammatory activity (84.89%) and anticoagulant effects at the highest tested dose (500 mg/kg) compared to the commercial counterpart. Structural characterization through UV-Vis, FT-IR, FT-Raman, and NMR analyses confirmed the presence of key functional groups consistent with κ-carrageenan in both samples. In summary, the study revealed that native carrageenan from K. alvarezii and commercial carrageenan exhibit promising therapeutic value in mitigating oxidative stress in diabetes, demonstrating antioxidant, anti-inflammatory, and anticoagulant activities. The native form generally shows stronger pharmacological effects, and both types belong to the κ-type.

As an encapsulating agent, Tarman et al. [60] examined the properties of carrageenan obtained through the enzymatic hydrolysis of marine algae using marine fungi, assessing its suitability for the production of hard capsules. The key findings indicated that the carrageenan yield reached 10% in the KK treatment (semi-refined carrageenan without gelatinization) and 66% in the KB treatment (semi-refined carrageenan with gelatinization), with the higher yield in KB attributed to the presence of abundant cellulose, pigments, and other compounds. The resulting carrageenan showed a moisture content of 13%, ash content of 8%, and cellulose content of 8%. Its viscosity was measured at 45 cP, and the gel strength was 175 gf. Hard-shell capsules formulated with this carrageenan met the standard requirements for dimensions, weight, disintegration time, and moisture content. In conclusion, the semi-refined carrageenan produced by enzymatic hydrolysis using marine fungi proved suitable for manufacturing hard capsules, exhibiting appropriate physical and chemical properties.

In the final subcategory of health/medicine, Amruth et al. [38] developed transparent and absorbent biodegradable films for wound dressing applications by combining kappa-carrageenan (KC) with polyvinylpyrrolidone (PVP) using solvent casting and lyophilization techniques. The lyophilized films demonstrated superior absorption capacity (9.17 g/cm²) and effective moisture control, whereas the solvent-cast films achieved 78% transmittance, enabling direct observation of the wound site. Mechanical testing revealed high tensile strength (31.5 MPa) and excellent folding endurance (410 folds), ensuring structural durability. Both film types exhibited strong in vitro bactericidal activity against MRSA and E. coli. In vivo wound healing studies using Wistar rats showed complete wound closure in 16 days with 91.1% closure rate, outperforming untreated controls (76.7%). The absorbent dressing also displayed complete biodegradability, with full degradation observed in sacrificed animals by day 60. In conclusion, this innovative combination of biopolymers and fabrication methods yielded high-performance, sustainable carrageenan-based films with promising attributes for drug delivery, absorption, biodegradability, and comprehensive wound management.

Carrageenan offers unique properties that make it particularly valuable in biomedical applications. Its distinct gelation mechanisms, characterized by the ability to form gels in response to changes in temperature, ionic strength, or pH, allow for a versatile range of formulations [11,61]. Moreover, carrageenan’s high-water absorption capacity contributes to its effectiveness as a biomaterial. By retaining moisture, carrageenan-based products can facilitate wound healing processes, reducing the risk of infection while promoting tissue regeneration. This characteristic is especially beneficial in creating dressings that maintain a moist environment, essential for optimal healing conditions [61].

Carrageenan is also biocompatible, which is crucial for medical applications. Its natural origin means it has a lower risk of causing adverse reactions when in contact with human tissues. Furthermore, its versatility allows it to be combined with other polymers or bioactive agents, enhancing its functionality [62]. Overall, the unique properties of carrageenan, coupled with ongoing innovations in its application, highlight its significant role in the future of biomedical materials.

3.3. Human Food

Ten articles were found published in the human food sector (

Table 2. Articles published in the CAPES Periodicals Portal and in the Scopus database (2010–2025) on the use of carrageenan extracted from the seaweed Kappaphycus alvarezii in Human Food (n = 10).

Area	Nº	Target Effect	Matrix Used	Results	References
Edible films	1	Semi-refined carrageenan (SRC), ulvan, and their combination, in edible films to assess mechanical, and functional properties	SRC, ulvan polysaccharide, and a combination of both	The combined film showed higher mechanical strength and stability. The films demonstrated significant antioxidant activities, including hydroxyl radical scavenging, metal ion chelating, and reducing power	Ganesan et al. [20]
	2	Semi-refined carrageenan (SRC) based edible films as a coating for chicken breast filets	SRC and bio-nanocomposite film	Mechanical strength, barrier properties, and suitability for food preservation indicate the potential of these films to extend the shelf life and maintain the quality of chicken breast filet	Praseptiangga et al. [42]
	3	algal polysaccharides like carrageenan for biodegradability and barrier functions. Bamboo fiber enhances mechanical strength and sustainability	Carrageenan from K. alvarezii, bamboo fiber, and glycerol	Films composed of biopolymers derived from red marine algae and reinforced with bamboo fiber serve as packaging films in the food industry	Abdul et al. [55]
	4	Different concentrations of palmitic acid and zein affect the mechanical properties and water vapor barrier of edible films refined based on kappa-carrageenan	Refined kappa-carrageenan powder, palmitic acid, and zein	The incorporation of palmitic acid and zein into refined kappa-carrageenan-based films shows potential for developing food packaging materials with enhanced moisture barrier properties, although it may affect mechanical strength	Praseptiangga et al. [46]
	5	Carrageenan and bionanocomposites enable the development of advanced films for food packaging applications	Silver nanoparticles (AgNPs), nanocellulose from residual biomass, and carrageenan from K. alvarezii	Bionanocomposite films of carrageenan/nanocellulose/silver nanoparticles using marine algae demonstrated their potential as functional and sustainable materials for food packaging due to their mechanical, barrier, thermal, and antimicrobial properties	Jaffar et al. [57]
Ice cream	1	Combination of kappa and iota carrageenan blend as a gelatin substitute in ice cream	Carrageenan flour of K. alvarezii and E. spinosum	The addition of a kappa and iota carrageenan blend in ice cream manufacture can effectively serve as a substitute for gelatin. Therefore, it represents a promising innovative emulsifier for ice cream production	Suryani et al. [43]
	2	Extraction of phycoerythrin (PE) and encapsulate it with carrageenan (PE-Kc) and guar gum (PE-Gg) to assess stability and functionality in ice cream	PE, PE-Kc and PE-Gg	Microencapsulation with PE-Kc and PE-Gg enhanced the stability of PE in ice cream, maintaining color intensity for 90 days. These matrices also influenced the rheological, sensory, and functional properties of the ice cream	Ganesan et al. [19]
Food additive agent	1	Potential of Kapparazii powder as a healthy ingredient for food industry applications	K. alvarezii powder and L929 mouse fibroblast cells	Kapparazii powder demonstrated its potential as a valuable and nutrient-rich hydrocolloid for the food industry, with favorable physicochemical properties and no cytotoxic effects	Sjamsiah et al. [54]
	2	Potential of λ- and α-carrageenans extracted from red algae as natural bread improvers	Basic bread formula and K. alvarezii carrageenans	λ- and α-carrageenans from red algae can serve as effective natural bread improvers, significantly increasing bread volume, improving crumb texture and structure, and extending shelf life by delaying moisture loss and maintaining elasticity, particularly at lower concentrations	Widyastuti et al. [45]
Flocculating agent	1	Natural flocculant derived from red algae, specifically targeting carrageenan extraction, for use in sugarcane juice treatment	Sugarcane juice extracted from the CTC072361 variety and samples of red from algae K. alvarezii	Potential of red algae extract as a natural bioflocculant for clarifying sugarcane juice, offering a sustainable alternative to synthetic flocculants	Alcantra et al. [58]

), with publication years as follows: 2013 (n = 1), 2018 (n = 3), 2019 (n = 1), 2020 (n = 1), 2021 (n = 1), 2022 (n = 1), 2023 (n = 1), and 2025 (n = 1). Among these, the primary focus was on the development of cosmetic films (n = 5), followed by incorporation in ice cream (n = 2), as a food additive (n = 2), and as a flocculating agent (n = 1).

Research on innovative next-generation edible films has utilized natural polysaccharides extracted from K. alvarezii. Ganesan et al. [20] reported a yield of 31.55% for the extraction of semi-refined carrageenan (SRC), with viscometric analysis indicating molecular weights of approximately 210 kDa. Three distinct film formulations were developed using SRC and ulvan polysaccharides; the composite film (SRC + ulvan) exhibited significantly higher tensile strength (48.12 MPa), followed by the SRC film (47.56 MPa), whereas the ulvan polysaccharide film showed lower tensile strength (36.78 MPa). Regarding elongation at break, the composite film demonstrated superior performance (11.02 ± 0.98%) compared to SRC and ulvan films (9.24 ± 0.48% and 7.98 ± 1.24%, respectively). Water vapor permeability (WVP) was significantly reduced in the composite film (7.82 ± 0.15 × 10⁻⁸ g·m⁻·s⁻·Pa⁻), indicating superior barrier properties due to its denser structure. In contrast, SRC and ulvan films had WVP values of 9.24 ± 0.41 × 10⁻⁸ and 9.96 ± 0.15 × 10⁻⁸ g·m⁻·s⁻·Pa⁻, respectively. These films demonstrated significant antioxidant activities, with the ulvan-based film showing the highest hydroxyl radical scavenging ability, inhibiting between 3.05% and 68.26%, outperforming SRC and composite films. Metal ion chelation varied from 15.04% to 68.26%, with the composite film exhibiting the strongest activity at higher concentrations (10 mg/mL). The reducing power ranged from 0.092% to 0.81% across all film types. Collectively, these results demonstrate that the films, characterized by their high tensile strength, superior elongation, reduced water vapor permeability, and significant antioxidant properties, present promising candidates for active food packaging applications.

Praseptiangga et al. [42] investigated the formulation and characterization of a composite edible film based on semi-refined k-carrageenan (SRKC) incorporated with palmitic acid (PA), assessing its packaging application for minimally processed chicken breast filets. Mechanical properties, including tensile strength (TS) and elongation at break (EAB), were evaluated, with TS values for the SRKC composite films ranging from 13.84 to 16.82 MPa, and EAB varied between 9.86% and 9.89%. The incorporation of PA at 10% (w/w) initially led to a decrease in TS and EAB, as an increase to 15% (w/w) improved the SRKC’s mechanical performance. Barrier properties were also evaluated, revealing a significant improvement in water vapor transmission rate (WVTR) for films containing 15% PA (6.51 ± 1.58 g/h·m²), compared to 5% (8.93 ± 1.89 g/h·m²) and 10% (8.26 ± 2.03 g/h·m²) PA. The decrease in WVTR is likely attributed to increased film thickness and reduced water mobility, indicating enhanced moisture barrier capacity. These findings indicate that PA-incorporated SRKC films possess promising moisture barrier properties for food packaging, effectively extending shelf life and preserving the quality of minimally processed chicken breast fillets.

Jaffar et al. [57] developed and characterized bionanocomposite films derived from K. alvarezii, utilizing carrageenan (Cr) as the polymer matrix, nanocelulose (NC) as a reinforcing agent, and silver nanoparticles (AgNPs) as an antimicrobial component, to assess their suitability for food packaging applications. The pure carrageenan film (Cr) served as the baseline material but displayed the lowest mechanical performance, with a maximum load of 8.72 N, tensile strength of 3.18 MPa, and elastic modulus of 26.35 MPa, accompanied by limited flexibility and inherent brittleness. It also exhibited poor moisture barrier properties, evidenced by a moisture content of 14.70%, high moisture absorption (98.8%), and water solubility (59.25%). In comparison, the Cr/NC/AgNPs bionanocomposite films exhibit markedly improved mechanical properties, including a maximum load of 16.73 N, tensile strength of 6.81 MPa, elastic modulus of 32.18 MPa, and elongation at break of 18.73%. These composite films also demonstrated excellent optical properties, enhanced moisture barrier performance with a water vapor transmission rate of 5.62 g/m²·day, and superior thermal stability, with decomposition temperatures reaching up to 282 °C. The study concludes that these bionanocomposite films represent a sustainable, functional, and highly effective material for food packaging, addressing environmental concerns related to plastic waste, despite a relatively high solubility rate of 47.7%.

Praseptiangga et al. [46] examined the effects of varying concentrations of palmitic acid and zein on the mechanical properties and water vapor barrier performance of refined kappa-carrageenan-based edible films. The results indicated that the incorporation of palmitic acid and zein generally increased film thickness. While the addition of these compounds did not enhance the mechanical strength of the films, a slight increase in elongation at break (EAB) was observed. The water vapor transmission rate (WVTR) decreased with higher palmitic acid concentrations, reflecting improved moisture barrier properties, although it tended to rise at elevated zein levels. In conclusion, the study highlights the promising potential of refined kappa-carrageenan films modified with palmitic acid and zein for developing advanced food packaging materials, particularly due to their enhanced moisture barrier capabilities.

Abdul et al. [55] developed edible films composed of bamboo fibers embedded in a polymeric matrix derived from unmodified and chemically modified marine algae K. alvarezii and evaluated their potential suitability for food packaging applications. The investigation centered on biocomposite films prepared using K. alvarezii as a source of carrageenan. The findings demonstrated that incorporating bamboo fibers into the carrageenan matrix substantially improved mechanical properties, including tensile strength, Young’s modulus, and elongation at break, with optimal performance achieved at a 15% bamboo fiber loading in unmodified carrageenan films. The study further revealed that the addition of bamboo fibers reduced the water vapor permeability (WVP) of the films, indicating enhanced moisture barrier performance. Chemical modification of the carrageenan promoted stronger interfacial bonding with fiber reinforcement, resulting in improved water vapor barrier properties in the biocomposite films. In conclusion, the research highlights the promising potential of these renewable and biodegradable biopolymer composite films—particularly those based on modified carrageenan—as advanced materials for food packaging, owing to their enhanced mechanical strength and barrier characteristics that may contribute to extending the shelf life of packaged products.

Regarding the incorporation of carrageenan in ice cream, Suryani et al. [43] investigated the formulation of ice cream using a combination of kappa and iota carrageenans, comparing it with gelatin-based ice cream. The results demonstrated that ice cream formulated with this carrageenan blend exhibited favorable nutritional properties, including low fat amount (6.995%), high protein (9.585%), and fiber (17.695%) contents, compared to gelatin-based ice cream. Additionally, a viscosity value of 0.87% indicated that the kappa and iota carrageenan combination effectively replaced gelatin (0.745%) as a stabilizer in ice cream. Hedonic tests evaluating aroma, flavor, and texture showed positive results for ice creams containing kappa and iota carrageenan, with scores ranging from 5.8 to 6.1. Flavor parameters were significantly influenced by panelist preferences, with the kappa and iota combination preferred for its distinct and smoother taste. Carrageenan did not affect the ice cream’s aroma, and its texture was appreciated for its resistance to melting. These findings highlight carrageenan’s potential as an innovative and promising emulsifier for enhancing ice cream formulations.

In another study, Ganesan et al. [19] investigated the extraction of the pigment phycoerythrin (PE) from K. alvarezii, assessing its physicochemical, rheological, and sensory attributes. The study also examined the antioxidant activity and color of PE when incorporated into ice cream using various encapsulation matrices. The matrices used for microencapsulation of phycoerythrin were kappa carrageenan (PE-Kc) and guar gum (PE-Gg). Encapsulation efficiency (EE) was higher for PE-Kc, with values of 82.56 ± 0.18%, and PE loading of 56.78 ± 0.96%. The usage of carrageenan as the encapsulating wall material resulted in lower hygroscopicity in PE-Kc (0.25 ± 0.09). Both PE-Kc (86.94 ± 1.02) and PE-Gg (90.14 ± 0.18) showed high water solubility, with particle sizes ranging from 10 to 80 µm for PE-Kc. PE-Kc exhibited greater crystal formation, likely due to rapid cooling and abrupt moisture content changes. Incorporation of PE-Kc increased the total protein content in ice cream (4.9 ± 0.02% → 6.8 ± 0.03%) and total soluble solids (40.14 ± 0.10% → 44.41 ± 0.10%) after 90 days. The low flow index for PE-Kc (0.721 ± 0.164) indicates higher polysaccharide entanglement in the encapsulation matrix, affecting ice cream’s shear rate. Sensory analysis of ice cream with PE-Kc showed improved scores for color (7.9), flavor (7.5), texture (7.9), and aroma (7.7). Color analysis demonstrated that microencapsulation preserved pigment tone, with ice cream containing PE-Kc showing increased redness (a* = 58.09 ± 0.19) over storage, as lightness (L) values remained stable (~66.26 ± 2.46) for the first 60 days before decreasing to day 90 (58.05 ± 0.12). Antioxidant activity confirmed by DPPH and FRAP assays showed radical scavenging of 30.47%, 20.45%, and 18.56% for PE-R, PE-Kc, and PE-Gg, respectively, with significant FRAP increases of 40.78% and 43.04% for PE-Kc and PE-Gg. Overall, microencapsulation effectively preserves the color intensity, stability, and antioxidant properties of phycoerythrin over time, with PE-Gg showing slightly greater stability than PE-Kc, enhancing product quality and functional benefits.

As a food additive, Sjamsiah et al. [54] evaluated Kapparazii powder™, a food ingredient derived from K. alvarezii produced through an eco-friendly spray-drying process. The study focused on quantifying and characterizing its key properties. The study found that Kapparazii powder™ contained a higher protein content (5.11%) compared to locally marketed κ-carrageenans, which typically exhibit protein levels ranging from 0.08% to 0.31%. Additionally, its lipid content was 1.00%, consistent with values commonly observed in tropical seaweeds, while its crude fiber content (0.93%) exceeded that of local κ-carrageenan (0.12–0.32%). The powder also displayed distinctive physicochemical properties, including a high swelling capacity (100 mL·g⁻¹), water retention capacity (4.67 g·g⁻¹), oil retention capacity (5.11 g·g⁻¹), and gel strength of 82.77 gf. Based on its nutritional profile and functional attributes, Kapparazii powder™ shows considerable potential as a nutrient-rich hydrocolloid and a viable alternative to conventional carrageenan products for various food industry applications.

Also, as a food additive, Widyastuti et al. [45] explored the potential of λ-carrageenan extracted from the red seaweed Halymenia sp. and κ-carrageenan from K. alvarezii as natural bread improvers to enhance overall bread quality. The findings showed that incorporating 0.4% λ-carrageenan from Halymenia sp. and 0.2% κ-carrageenan significantly increased loaf volume by 30–50%, improved crumb texture and structure, reduced moisture loss by 2–6%, and preserved crumb elasticity by 5–15% over 96 h of storage compared to the control bread. In addition, the 0.4% λ-carrageenan treatment proved most effective for maintaining elasticity and minimizing moisture loss during storage. While lower concentrations of both carrageenans generally enhanced sensory acceptance, these improvements were not statistically significant.

In the final subcategory, Alcantara et al. [58] developed a natural flocculant derived from red seaweed carrageenan, specifically from K. alvarezii, for the clarification of sugarcane juice. They determined the optimal conditions for its preparation, dosage, and application by comparing univariate and multivariate experimental designs. The study focused on the polysaccharide fraction of carrageenan extracted from this macroalga. The results showed that the red seaweed extract, rich in carrageenan, significantly enhanced the clarification process. In particular, a dosage of 1000 mg·L⁻¹ in the univariate experimental design and 500 mg·L⁻¹ in the multivariate design yielded satisfactory outcomes, improving flocculation formation, reducing turbidity, and increasing the sedimentation rate of impurities in the sugarcane juice. The effectiveness of carrageenan is attributed to its linear polysaccharide structure, characterized by alternating α-(1-3)-D-galactose-4-sulfate and β-(1-4)-3,6-anhydro-D-galactose linkages, which impart negative charges and increase molecular weight, thereby promoting efficient flocculation. In conclusion, the investigation successfully demonstrated that carrageenan extracts from K. alvarezii serve as effective bioflocculants for sugarcane juice clarification, providing a sustainable alternative to synthetic compounds and exhibiting strong adaptability for the sugarcane industry.

The escalating global concern regarding the widespread use of conventional plastics in food packaging necessitates urgent exploration of innovative and sustainable alternatives. A promising solution lies in the use of edible films made from carrageenan, which can be processed into a semi-refined form suitable for film production [3,11,33]. These films offer significant social and environmental benefits by providing effective packaging, particularly for lipid-rich foods, due to their inherent antioxidant properties [63].

Research indicates that cultivating K. alvarezii adds substantial value to the food industry through the versatile applications of carrageenan and the phycoerythrin pigment [19,20,42,43]. Additionally, it supports local economies by providing plant-based alternatives that match or exceed traditional stabilizers, offering consumers healthier options made from natural and sustainable ingredients. Such innovations underscore carrageenan’s vital role in the food industry, promoting public health and environmental sustainability [64]

3.4. General Industry

In the General Industry sector, eight publications were recorded (

Table 3. Articles published in the CAPES Periodical Portal and Scopus database (2010–2025) on the use of carrageenan extracted from the seaweed Kappaphycus alvarezii in General Industry (n = 8).

Area	Nº	Target Effect	Matrix Used	Results	References
Biomaterials	1	Production of Kappaphycus-based (KBF) and carrageenan-based (CBF) bio-nanocomposite films enhanced with zinc oxide (ZnO), cupric oxide (CuO), and silicon dioxide (SiO2)	CBF and KBF matrices with ZnO, CuO, SiO2 nanoparticles	The KBF proves to be a viable alternative, particularly due to its superior antimicrobial activity and enhanced barrier properties	Sudhakar et al. [8]
	2	Development of biodegradable films for food packaging and commercial applications, leveraging optimized mechanical strength, water vapor permeability, and biodegradability	Carrageenan extracted via alcohol method from K.s alvarezii red seaweed combined with rice starch	Mechanical properties and water vapor permeability improved with higher concentrations; optimal film achieved at low carrageenan and high rice starch, showing broad commercial potential	Rajasekar et al. [50]
	3	Carrageenan combined with starch and glycerol in the development of films for edible food packaging, disposable utensils, and agricultural films	Carrageenan from K. alvarezii, tapioca starch, and glycerol	Films made from starch and carrageenan exhibit impressive thermal, mechanical, and biodegradability properties. These characteristics suggest their viability as substitutes for conventional plastics	Yap et al. [56]
	4	Feasibility of producing sustainable bioplastics from seaweed and snail-derived chitin as an eco-friendly alternative to petroleum-based plastics	Starch and carrageenan from K. alvarezii and chitin from the shells of ramshorn snails Planorbarius corneus	Carrageenan effectively mediated starch-chitin interactions in the composite bioplastic, resulting in a denser network structure. Chitin and carrageenan incorporation significantly improved tensile strength and water resistance by mitigating hydrophilicity and filling microstructural voids	Leong et al. [39]
	5	Development biodegradable and biocompatible materials with tailored mechanical properties suitable for food packaging and biomedical fields	Carrageenan (extracted from K. alvarezii), sodium alginate (from Sargassum wightii), and agar (from Gracilaria crassa and Gelidiella acerosa)	The carrageenan, sodium alginate, and corn starch bioplastic exhibited tensile strength (TS) and elongation at break, serving as a viable ecological alternative to conventional plastics with potential for food packaging and biomedical applications due to its biocompatibility and degradability	Sarangam et al. [52]
	6	Manufactures biopolymer films to serve as an eco-friendly alternative to conventional petroleum-derived plastics for food packaging applications	Extracted kappa-carrageenan and glycerol as a plasticizing agent	Films produced with the KCG extract demonstrated superior tensile strength and greater thermal stability, showing high potential as sustainable marine biomaterials for advanced industrial applications	Alfatah et al. [49]
Bioproduct	1	Development film immersion and thermal curing while analyzing how the concentration of the crosslinking agent affects the hydrogel’s properties	kappa carrageenan from K alvarezii ang glutaraldehyde	It is possible to successfully produce a chemically crosslinked kappa-carrageenan hydrogel with glutaraldehyde through a film immersion method and thermal curing	Distantina et al. [41]
Biorefinery	1	Production of lactic acid from detoxified K. alvarezii hydrolysates	K. alvarezii hydrolysates detoxified with regenerated activated charcoal, in bioreactor fermentations with Lactobacillus pentosus	The fermentation achieved a maximum lactic acid concentration in extended fed-batch mode, demonstrating effective conversion of the hydrolysates into lactic acid	Tabacof et al. [34]

), with publication years as follows: 2013 (n = 1), 2022 (n = 1), 2023 (n = 2), 2024 (n = 2), and 2025 (n = 2). Applications of carrageenan extracted from K. alvarezii were found for the development of biomaterials (n = 6) and bioproduct (n = 1), as well as for applications in biorefining (n = 1).

In the development of biomaterials, which showed the highest volume of research, the first study by Sudhakar et al. [8] investigated the properties of bio-nanocomposite films made from commercial-grade κ-carrageenan and whole K. alvarezii seaweed. This study incorporated nanofillers such as zinc oxide (ZnONPs), cupric oxide (CuONPs), and silicon dioxide (SiO₂NPs). Incorporating these nanoparticles improved crystallinity and reduced water vapor transmission rate (WVTR), moisture content, solubility, and water absorption, enhancing barrier properties. Surface wettability indicated increased hydrophobicity in Kappaphycus-based bio-nanocomposite films (KBF) with nanoparticles, while standard carrageenan-based bio-nanocomposite films (CBF) had minimal changes. KBF films had similar wettability to CBF films. Mechanically, ZnO and CuO enhanced tensile strength and elongation at break due to hydrogen bonding. Generally, CBF films have higher tensile strength than KBF ones. Thermal analysis showed improved stability with higher decomposition temperatures for both film types. Optical analysis revealed that nanoparticles reduced transparency, with pure κ-carrageenan films showing 50.3% transmittance at 660 nm, compared to 30.6% for KBF films. Surface morphology studies indicated increased roughness in KBF films, as shown by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Nanoparticles improved antibacterial activity against Staphylococcus aureus and Escherichia coli, with KBF films reducing bacterial counts by 2 to 4 logs within 24 h. Moreover, nanoparticle-loaded films degraded more slowly in soil, suggesting antimicrobial-induced biodegradation retardation, while KBF and CBF films exhibited comparable degradation rates. This study highlights the economic and ecological benefits of using whole seaweed biomass and the potential of K. alvarezii-based bio-nanocomposite films for food packaging, biomedical, and environmental applications.

Yap et al. [56] investigated the synergistic effects of starch and carrageenan extracted from K. alvarezii in the formation of composite films, assessing their physicochemical and degradable properties as potential sustainable alternatives to conventional plastics. The study focused on extracting carrageenan and combining it with starch and glycerol to produce algae-based films. The results showed that incorporating carrageenan significantly enhanced the overall thermal stability of the films while increasing water solubility and moisture content, although it reduced the degradation rate and swelling degree. These effects were attributed to the crystalline structure of carrageenan, which provides a more rigid arrangement compared to starch polymers, whereas the addition of starch improved elongation and surface morphology, resulting in more balanced properties. Furthermore, carrageenan-based films exhibited higher tensile strength and lower elongation compared to the negative control. Films containing 50% carrageenan, in particular, displayed notable thermal, mechanical, and biodegradability characteristics, demonstrating their viability as substitutes for conventional plastics, especially in applications such as edible food packaging.

Rajasekar et al. [50] investigated the potential of carrageenan extracted from K. alvarezii for the development of biodegradable films. The carrageenan was isolated using an alcohol extraction method, and rice starch was added to enhance the mechanical performance of the films. Biodegradable films were prepared via the phase inversion technique, incorporating carrageenan at concentrations of 1%, 1.5%, and 2% (w/v) combined with rice starch at 0%, 1%, 1.5%, and 2% (w/v). The findings indicated that increasing the concentrations of both carrageenan and rice starch improved the mechanical properties and reduced water vapor permeability of the films. The optimal film formulation was achieved with 1.5% carrageenan and 2% rice starch. These results demonstrate a wide range of potential commercial applications and highlight opportunities for further development of rice starch-reinforced carrageenan-based biodegradable films.

Leong et al. [39] investigated the feasibility of developing seaweed-based bioplastics by combining starch and carrageenan from K. alvarezii with chitin extracted from ramshorn snails (Planorbarius corneus). The incorporation of carrageenan as a gelling agent promoted the formation of a strong network structure, markedly improving the mechanical strength, surface roughness, and water barrier properties of the resulting bioplastic films. In addition, carrageenan served as a nitrogen-rich energy source and created porous networks that supported microbial colonization and enzymatic activity, thereby accelerating biodegradation. The study concluded that these bioplastics, derived from seaweed and chitin, offer a viable and environmentally friendly alternative to conventional petroleum-based plastics, exhibiting over 76% weight loss or complete degradation through the activity of soil microorganisms such as Acinetobacter spp. and Burkholderia cepacia.

Sarangam et al. [52] identified a sustainable source of bioplastics by extracting polysaccharides, particularly carrageenan, from K. alvarezii. They assessed the mechanical and biodegradable properties of the resulting films, both as standalone materials and in various composite formulations. Experimental findings showed that a pure carrageenan film (F1) exhibited a tensile strength of 1.7365 N/mm² and an elongation at break of 27.36%, whereas the optimized formulation (F6), which combined carrageenan with sodium alginate and corn starch, achieved markedly higher tensile strength of 3.051 N/mm² and elongation of 31.275%. In addition, molecular docking and dynamics simulations revealed strong binding interactions between carrageenan and the CutL1 enzyme from Aspergillus oryzae, with a glide score of −4.229 kcal/mol and a stable average RMSD of 1.23 Å, supporting the material’s biodegradability. In conclusion, these results demonstrate that carrageenan derived from seaweed, especially in composite formulations such as F6, offers a non-toxic, mechanically robust, and environmentally sustainable alternative to conventional petroleum-based plastics for applications in packaging and biomedical fields.

Finally, Alfatah et al. [49] isolated kappa-carrageenan from K. alvarezii using hydrated choline chloride-based deep eutectic solvents (DES). They assessed the functional properties of the resulting biopolymer films for potential packaging applications. Experimental findings indicated that the glycerol-based DES (KCG) delivered the highest extraction yield of 65.38% and the greatest carbohydrate content of 74.53%. In addition, the KCG extract displayed improved thermal stability relative to other variants, with an onset decomposition temperature of 215 °C and a maximum degradation temperature of 249 °C. For the biopolymer films, those prepared with KCG achieved a maximum tensile strength of 28.63 MPa and a water contact angle of 76.93°, reflecting enhanced mechanical strength and hydrophobicity compared to films derived from urea (KCU) or ethylene glycol (KCE) DES. These films also exhibited a more organized and compact internal morphology, with the lowest surface roughness measured at 86.37 nm. In conclusion, the application of hydrated choline chloride-glycerol DES offers an effective and sustainable approach for extracting high-quality kappa-carrageenan, yielding marine-derived biomaterials that show strong potential as alternatives to conventional petroleum-based plastics in food packaging.

In the field of bioproducts, Distantina et al. [41] enhanced the stability of kappa-carrageenan extracted from K. alvarezii by employing a chemical crosslinking approach with glutaraldehyde (GA) to form a stable hydrogel structure. Experimental findings showed that a minimum GA concentration of 0.027 g per gram of polymer was required to effectively crosslink the hydroxyl groups, as lower levels did not adequately retain water. Increasing the GA concentration from 3% to 5% reduced the equilibrium swelling degree in water by up to 60%, with values of 7.34 at 3% GA and 2.78 at 5% GA. Thermal analysis further revealed improved stability, as the exothermic decomposition peak shifted from 167 °C in the uncrosslinked film to 172 °C in the crosslinked material. The resulting hydrogels exhibited pH-sensitive behavior, decomposing in highly acidic conditions (pH~1) within approximately 10 min, while remaining stable and insoluble in water, buffer, and NaOH solutions. In conclusion, kappa-carrageenan can be effectively crosslinked by immersing films in 3–5 wt% GA solutions and curing at 110 °C, yielding pH- and salt-responsive hydrogels with enhanced thermal stability suitable for diverse industrial and biomedical applications.

Finally, with applications in biorefinery, Tabacof et al. [34] investigated lactic acid production from K. alvarezii hydrolysates using Lactobacillus pentosus, focusing on various bioreactor operation modes and the reusability of activated charcoal. During fermentation, L. pentosus ATCC 8041 effectively fermented synthetic galactose and glucose in MRS medium, as well as 30% (w/v) K. alvarezii hydrolysates. Using an inoculum concentration of 0.6 g/L, fermentable sugars were depleted between 12 and 16 h post-inoculation. Pulse sugar feeding led to complete galactose consumption and a maximum lactic acid concentration of 90.9 g/L. In terms of productivity, batch fermentation with a 0.6 g/L inoculum achieved 3.57 g/(L·h), while fed-batch applications reached a maximum cell mass of 2.3 g/L. Chiral HPLC analysis indicated that L. pentosus produced nearly equal amounts of L(-) and D(+) lactic acid, i.e., ~49.5% and 50.5%, respectively, across all fermentations. Activated charcoal was effective in removing hydroxymethylfurfural (HMF) from detoxified K. alvarezii hydrolysates, maintaining HMF concentrations below 0.70 g/L after three regeneration cycles. Fermentable sugar loss due to the regenerated charcoal was 8%, 9%, and 18% after the first, second, and third regenerations, respectively. A production scheme estimated that one ton of washed, dried seaweed could yield approximately 115 kg of lactic acid at the laboratory scale. This study highlights the potential of K. alvarezii hydrolysates for lactic acid production using L. pentosus, emphasizing the benefits of fed-batch strategies for higher yields and confirming the feasibility of activated charcoal reuse for detoxification.

The development of carrageenan-based biomaterials has gained significant attention within the general industry. Notably, biocomposites and bioplastics have emerged as sustainable alternatives to conventional materials. These innovative products harness the unique properties of carrageenan, including its biodegradability and functional versatility, making them particularly advantageous for various applications [65,66,67]. Biocomposites, which combine carrageenan with other natural or synthetic materials, not only enhance the mechanical properties but also improve the overall performance of the final products. This approach allows for the creation of materials that can meet specific industry requirements while minimizing environmental impact [68]. Furthermore, the use of carrageenan in bioplastic formulations offers an effective solution to the escalating concerns over plastic pollution, as these materials can break down naturally over time [65].

Furthermore, although only one study has been validated with applications in biorefinery, this is an important approach that represents a significant pathway to reducing dependence on petrochemicals and promoting a circular bioeconomy. The concept of marine algal biorefineries, which aims to extract multiple valuable components from biomass, presents a route towards more sustainable industrial processes. Biorefinery setups utilizing K. alvarezii can co-produce carrageenan alongside valuable products such as ethanol, plant biostimulants, fertilizers, and biogas, thereby maximizing resource utilization and minimizing waste [69,70].

3.5. Animal Nutrition

In the field of animal nutrition, six manuscripts were identified, with publications in 2020 (n = 1), 2021 (n = 2), 2023 (n = 2), and 2024 (n = 1). Of these articles, five focused on aquaculture, while one addressed livestock (

Table 4. Articles published in the CAPES Periodical Portal and Scopus database (2010–2025) on the use of carrageenan extracted from the seaweed Kappaphycus alvarezii in Animal Nutrition (n = 6).

Area	Nº	Target Effect	Matrix Used	Results	References
Aquaculture	1	Processed product of K. alvarezii as a thickening agent in a gel diet for rabbitfish	Seaweed flour, fermented seaweed flour, carrageenan flour and seaweed soft	Fermented seaweed flour is the best thickener in the gel diet for rabbitfish, as it maximizes fish nutritional quality and protein utilization efficiency	Saade et al. [10]
	2	Carrageenan effect on the growth and health parameters of the Pacific white shrimp Litopenaeus vannamei	Different concentration of carrageenan obtained from K. alvarezii	Low levels of carrageenan in the diet can benefit the intestinal microbiota composition and improve resistance to WSSV without negatively affecting growth or overall health status of the shrimp	Mariot et al. [40]
	3	Carrageenan supplementation in the diet affects the immune response and the expression of immune-related genes in white shrimp Litopenaeus vannamei	Carrageenan flour and white shrimp Litopenaeus vannamei	Diet supplementation with K. alvarezii carrageenan significantly improves innate immunity and immune gene expression in L. vannamei over a 15-day period, demonstrating its value in enhancing shrimp defense systems in aquaculture	Dhewang et al. [47]
	4	k-carrageenan as a natural immunostimulant agent to increase the immune response and survival rate of white vannamei shrimp Litopenaeus vannamei infected with the Infectious Myonecrosis Virus	White vannamei shrimp (L. vannamei), k-carrageenan flour from K. alvarezii and Infectious Myonecrosis Virus (IMNV)	The administration of this seaweed-derived compound increases hemocyte production, boosts phagocytosis, and possesses antibacterial properties that suppress the growth of Vibrio in the intestines, thereby ensuring higher survival in shrimp cultures	Azhar et al. [37]
	5	k-carrageenan as a functional ingredient with two primary purposes: to act as a growth promoter and as an immunostimulant to increase the resistance of post-larvae to acute salinity stress	Black tiger shrimp (Penaeus monodon) post-larvae and refined κ-carrageenan from k. alvarezii	κ-Carrageenan exhibits dual effects as a growth promoter and immunological stimulant against environmental stress, although the highest dose provides better protection but may eliminate growth benefits due to increased dietary fiber, which can hinder nutrient absorption	Jumah et al. [32]
Livestock	1	Evaluate effects of K. alvarezii extracts, rich in carrageenan, on broiler chicken growth, immunity, gut health, and antioxidant status	Broiler chickens (Vencobb 400), MVP1 alkaline, PBD1 aqueous K. alvarezii extracts	The aqueous PBD1 extract effectively enhances growth and immunity in broiler chickens by increasing villus width and crypt depth	Paulet al. [44]

).

Beginning with the subcategory that has the highest number of publications, aquaculture, Saade et al. [10] investigated the effects of products derived from K. alvarezii, used as thickeners in gelled diets, on nutrient utilization, protein retention (PR), protein efficiency ratio (PER), carbohydrate utilization, and hepatosomatic index in Siganus guttatus over a period of 30 days. The fish were fed diets containing dried algal flour (A), fermented algal flour (B), carrageenan flour (C), and fresh/mushy algae (D). Results showed significant differences in body nutrient content, with the highest crude protein in treatments B (43.52 ± 0.79) and C (43.63 ± 0.19), as the highest crude lipid content was detected in dried algal flour-treated animals (i.e., treatment A, 1628.79 ± 40.99). Additionally, the highest carbohydrate amount was found in treatment D (96.10 ± 1.56). Protein utilization was measured by PR and PER, with PR ranging from 63.55 ± 2.37% to 78.05 ± 4.39%, with treatment B achieving the highest retention. PER varied from 0.30 ± 0.04 to 0.44 ± 0.01, with treatment C significantly different from the others. Carbohydrate utilization was assessed through blood glucose (BG) levels, which ranged from 84.00 ± 8.72 mg/dL to 118.67 ± 47.37 mg/dL, showing no significant effect from the seaweed products. Hepatic glycogen content varied from 3.47 ± 0.24 mg/g (A) to 3.87 ± 0.09 mg/g (B), with significant differences detected. The hepatosomatic index (HSI) ranged from 0.87 ± 0.11% (C) to 1.41 ± 0.02% (B). The study concluded that rabbitfish effectively optimized diet utilization in gel diets, with fermented algal flour (B) identified as the superior product for enhancing body nutritional content, protein efficiency ratio, and protein retention.

Mariot et al. [40] investigated the effects of carrageenan derived from K. alvarezii on the growth, health, and disease resistance of Pacific white shrimp (Litopenaeus vannamei), particularly against white spot syndrome virus (WSSV). The study found that carrageenan supplementation improved WSSV resistance without negatively impacting growth. The final weights of the animals ranged from 8.50 g to 10.30 g, with feed conversion ratios between 1.42 and 1.67 g. All carrageenan treatments (e.g., 0.5%, 1.0%, 1.5%, and 2.0%) significantly reduced cumulative mortality 96 h after WSSV challenge, with the 1.5% level showing the highest survival rate and average agglutination titer (14.25 ± 0.67). Alpha diversity indices of the shrimp’s intestinal microbiota remained unchanged across carrageenan doses. Notably, an unclassified bacterium from the Rhodobacteraceae family (ASV 188) and bacteria from the Rubritaleaceae (genus Haloferula, ASV 64) and Caldilineaceae (ASV 432) increased as a result of the diets containing 0.5%, 1%, and 1.5% carrageenan. Overall, low levels of dietary carrageenan (up to 1.5%) may enhance resistance to WSSV in Pacific white shrimp while positively influencing intestinal microbiota composition, without compromising growth performance or overall health.

Dhewang et al. [47] assessed the immunostimulatory effects and modulation of gene expression in white shrimp (Litopenaeus vannamei) fed diets supplemented with carrageenan extracted from K. alvarezii. Experimental findings showed that carrageenan supplementation markedly enhanced several immune parameters over a 15-day feeding period, with the 20 g·kg⁻¹ dose producing the most pronounced increases in Total Haemocyte Count (THC), Phagocytosis Activity (PA), and Superoxide Dismutase (SOD) activity. The highest Phenoloxidase (PO) enzyme activity was observed at 15 g·kg⁻¹, while the Phagocytosis Index (PI) showed the greatest improvement at 5 g·kg⁻¹. Quantitative real-time PCR analysis revealed significant upregulation of transcript levels for the LGBP, Lectin, and proPO genes, with the strongest response occurring at the 20 g·kg⁻¹ concentration. In conclusion, carrageenan functions as an effective and environmentally sustainable immunostimulant that boosts innate immunity and upregulates immune-related gene expression in shrimp, offering a viable alternative to conventional chemical treatments in aquaculture.

Azhar et al. [37] assessed the efficacy of kappa-carrageenan extracted from K. alvarezii as a dietary immunostimulant at various inclusion levels to enhance immune responses and survival rates in the Litopenaeus vannamei shrimp challenged with Infectious Myonecrosis Virus (IMNV). Experimental findings indicated that a supplementation level of 20 g kg⁻¹ provided the most pronounced benefits, achieving a survival rate of 78%, which was markedly higher than the 58% recorded in the infected positive control group. This dose significantly enhanced the shrimp’s non-specific immune defenses, resulting in a total haemocyte count of 24.04 × 10⁶ cells mL⁻¹, phagocytic activity of 81%, and hyaline cell differentiation of 58%. In addition, kappa-carrageenan supplementation contributed to the suppression of intestinal pathogens, reducing the total Vibrio bacterial count to an optical density of 2.86 nm compared to 3.72 nm in the untreated infected group. In conclusion, dietary inclusion of 20 g kg⁻¹ kappa-carrageenan acts as an effective and environmentally sustainable immunostimulant that substantially strengthens immune parameters and increases resistance to viral infections in L. vannamei, presenting a viable alternative to traditional antibiotics in aquaculture.

Jumah et al. [32] assessed the potential of κ-carrageenan extracted from K. alvarezii as a dietary growth promoter and immunostimulant capable of mitigating acute salinity stress in black tiger shrimp (Penaeus monodon) postlarvae. In a 30-day feeding trial, diets supplemented with 0.15 and 0.30 g kg⁻¹ κ-carrageenan significantly increased final average body weight, weight gain, and specific growth rate relative to the control group, with the optimal inclusion level for growth performance estimated at 0.29 g kg⁻¹. In an acute salinity stress challenge, where salinity was reduced from 21 ppt to 4 ppt, mortality decreased linearly with increasing dietary κ-carrageenan concentration; the group receiving 0.60 g kg⁻¹ showed the lowest mortality rate (5.6%), compared to 44.4% in the unsupplemented control group. In conclusion, dietary κ-carrageenan functions as an effective functional feed ingredient that supports growth and enhances immune resilience against environmental stress in black tiger shrimp postlarvae, although the inclusion level required for maximum protection against salinity stress (0.60 g kg⁻¹) exceeds the optimum for growth and may potentially limit nutrient absorption due to elevated fiber content.

In the field of livestock farming, Paul et al. [44] examined the effects of supplementing broiler chickens (Vencobb 400) from 1 to 35 days post-hatch with dried alkaline extract (designated MVP1) and aqueous extract (designated PBD1) of K. alvarezii. The extract used was determined to be rich in carrageenan. Paul et al. [44] in a first experiment (Experiment I) tested seven diets, as follows: a basal diet supplemented with three levels (0.5, 1.5, or 5.0 g kg⁻¹) of either MVP1 or PBD1, along with a negative control, each assigned to 12 pen replicates of five birds. In a second experiment (Experiment II), three diets were evaluated: a negative control and PBD1 at two levels (1.0 or 1.5 g kg⁻¹), each provided to 16 pen replicates of five chicks. The PBD1 extract exhibited higher concentrations of total phenolics, phycobilins, and free radical scavenging activity (p < 0.01), but lower carrageenan content compared to MVP1. In Experiment I, supplementation with PBD1 at 1.5 g kg⁻¹ significantly increased body weight (p < 0.05) by 7.11% relative to the control. In Experiment II, both PBD1 levels improved body weight (p < 0.01) by 9.18% and 8.47%, respectively, compared to the control. The group receiving PBD1 at 1.0 g kg⁻¹ showed higher haemagglutination inhibition titter (p < 0.05), along with elevated expression of intestinal claudin 2, TLR2A, NOD1, avian β-defensin 4, interleukin 2, and interleukin 6 genes relative to the control. Supplementation did not affect feed efficiency or the activity of most antioxidant enzymes. Villus width and crypt depth were significantly greater in birds fed PBD1 at 1.5 g kg⁻¹. The findings indicate that inclusion of the dried aqueous extract of K. alvarezii at 1 g kg⁻¹ in the diet represents an effective approach to promote growth and enhance immunity in broiler chickens.

In the evolving landscape of aquaculture, there is an increasing need to identify natural ingredients that promote animal health while enhancing environmental sustainability [10,40]. In this sense, carrageenan derived from K. alvarezii has emerged as a promising natural supplement. However, it is important to note that some studies report potential toxic effects of that biopolymer in other animal models, such as weight loss and ulcers, which warrant further investigation [71,72]. Therefore, as highlighted in the study by Mariot et al. [40], determining the ideal dosage for this polysaccharide in aquaculture is crucial. Appropriate use of carrageenan can position it as a sustainable alternative in fish nutrition, promoting eco-friendly aquaculture practices, enhancing animal resilience, and reducing reliance on less sustainable feed additives.

Moreover, although only one article has been included based on the stringent criteria established, specifically, research focused on carrageenan extracted from K. alvarezii, the potential of carrageenan for use in livestock farming emerges as a promising alternative [73]. This area, however, remains underexplored and warrants further investigation. Given the increasing demand for natural additives [74], understanding the full potential of carrageenan could pave the way for innovative solutions in the livestock sector.

3.6. Agriculture

In the field of Agriculture, three studies were identified, published in 2018 (n = 1), 2020 (n = 1), and 2021 (n = 1). Two studies focused on the use of carrageenan extracted from K. alvarezii to induce plant defense, while one study utilized it as a biostimulant (

Table 5. Articles published in the CAPES Periodical Portal and Scopus database (2010–2025) on the use of carrageenan extracted from the seaweed Kappaphycus alvarezii in Agriculture (n = 3).

Area	Nº	Target Effect	Matrix Used	Results	References
Induction of defense	1	κ-carrageenan, from the red seaweed K. alvarezii as a potent inducer of plant resistance against anthracnose in chili peppers	Carrageenan of K. alvarezii and chili plants	κ-carrageenan extracted from K. alvarezii is a potent inducer of plant resistance and exhibits fungistatic activity against Colletotrichum gloeosporioides	Mani et al. [27]
	2	κ-carrageenan as a potent inducer of antioxidant defense and modulator of the chloroplast proteome in tomato plants against Septoria lycopersici	Carrageenan of K. alvarezii and tomato plants	Carrageenan of K. alvarezii is a potent inducer of defense in tomato plants against Septoria lycopersici. By reducing pathogen colonization, activating antioxidant responses, and modulating the chloroplast proteome to enhance stress tolerance	Mani et al. [28]
Biostimulant	1	Evaluate efficacy of radiation-modified kappa-carrageenan as a biostimulant to improve corn growth, yield parameters, and economic returns while reducing synthetic fertilizer use.	Radiation-modified kappa-carrageenan (RMKC) from K. alvarezii and Corn plants.	RMKC at 4 L/ha increased yield by 46%, boosted corn yield and profitability, and improved ear length and plant stand count.	Umhaw et al. [75]

).

To induce plant defense mechanisms, the study conducted by Mani et al. [27] investigated the potential of kappa-carrageenan in enhancing the defense responses of pepper plants (Capsicum annuum) against anthracnose caused by Colletotrichum gloeosporioides. Antifungal assays showed that k-carrageenan inhibited mycelial growth in a dose-dependent manner, achieving complete inhibition at 0.5% (w/v). This effect was linked to changes in plasma membrane permeability, confirmed by increased propidium iodide fluorescence. Foliar applications significantly increased guaiacol peroxidase (GPx) activity in pepper leaves before pathogen exposure, resulting in lower disease severity scores. Control plants exhibited 50.6% leaf browning by day 4, escalating to 91.3% by day 10, while k-carrageenan-treated leaves showed symptoms only from day 8 (41%) and 24% by day 10. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) indicated differential regulation of 34 proteins, with four novel proteins induced. Quantitative real-time PCR (qRT-PCR) confirmed the upregulation of pathogenesis-related (PR) genes. The findings suggest that k-carrageenan activates salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET) dependent defense pathways, demonstrating its dual role as a biofungicide and immune stimulant and offering an eco-friendly solution for anthracnose control.

The same research group, Mani et al. [28] investigated the efficacy of k-carrageenan in inducing antioxidant defense and proteomic changes in tomato plants against leaf spot disease caused by Septoria lycopersici. The study revealed significant protective effects in treated plants. Infected tomato plants exhibited leaf browning by day 6, reaching 98% disease severity by day 14. In contrast, k-carrageenan treatments at 0.025% and 0.050% delayed symptom onset until day 8, with 95% severity on day 14. Notably, 0.3% k-carrageenan delayed symptoms until day 10 and reduced disease scores by 32%. Fluorescence microscopy showed that 0.3% carrageenan pre-treatment reduced pathogen colonization, and treated leaves had more calcium oxalate crystals, potentially limiting pathogen spread. Reactive oxygen species (ROS) analysis indicated that k-carrageenan-treated leaves had time- and dose-dependent increases in hydrogen peroxide (H₂O₂) contents, peaking on days 6 and 8. Pre-treatment with 0.3% carrageenan led to rapid increases in superoxide anion radicals on days 6 and 12, whereas 0.025% carrageenan showed elevated superoxide dismutase activity on day 2, with decreases after day 4. Chloroplast proteome analysis via 2D-PAGE and MALDI-TOF identified 31 differentially expressed proteins, with 11 upregulated, including key proteins involved in stress response. Quantitative real-time PCR confirmed the upregulation of pathogenesis-related genes. These findings suggest that k-carrageenan activates salicylic acid and jasmonic acid/ethylene-dependent defense pathways, functioning as both a natural biofungicide and a stimulant of plant’s defense responses, offering a promising eco-friendly strategy for managing anthracnose disease.

As a biostimulant, Umhaw et al. [75] investigated the effects of radiation-modified kappa-carrageenan (RMKC) extracted from K. alvarezii on corn growth and yield. The study evaluated key agronomic parameters, including stand count, plant height, ear length, number of kernels per ear, and yield per hectare, following foliar application of RMKC at rates of 0 (control), 2, 3, and 4 L/ha applied at 14, 32, and 48 days after sowing. The highest application rate of 4 L/ha RMKC resulted in a significant yield increase of up to 46% compared to the farmer’s standard practice. Plants treated with 3 L/ha and 4 L/ha RMKC exhibited longer ears, while stand count was consistently higher in RMKC-supplemented treatments. Plant height and the number of kernels per ear were comparable across treatments. Economically, the 4 L/ha RMKC treatment generated up to 83% additional income. The authors recommend further studies to evaluate the long-term effects of RMKC supplementation and to identify the most effective and economically viable application rate for maize production.

Amid growing environmental concerns and the need for sustainable agricultural practices, organic methods utilizing biopolymers for plant disease control are gaining traction due to their ecological compatibility [10,40]. Carrageenan emerges as a promising strategy for crop protection, providing a non-toxic alternative to synthetic pesticides and studies indicating it poses no toxicity to host plants [27,76].

Research shows that carrageenan acts as a powerful elicitor of plant resistance, stimulating natural defense mechanisms [10,77]. It induces antioxidant defenses and modulates the chloroplast proteome, enhancing resistance to diseases such as anthracnose in peppers and leaf spot in tomatoes [78]. Additionally, carrageenan supports plants’ defense responses and growth by regulating various physiological and biochemical processes [79,80]. Moreover, carrageenan exhibits direct fungistatic potential by altering the membrane permeability of fungal pathogens such as C. gloeosporioides, indicating a direct biofungicidal action. This dual action—inducing host resistance while directly inhibiting pathogens—positions carrageenan as a natural fungicide with significant promise for enhancing crop resilience and plant disease control, thereby contributing to sustainable, low-impact agricultural systems [10,27,40].

4. Carrageenan Extraction

The widespread cultivation of K. alvarezii around the world is attributed to its rapid growth rate, high biomass productivity, and low cultivation costs. Undoubtedly, it plays an important role in the global hydrocolloid industry, contributing over 90% of the commercial carrageenan supply [11]. In terms of obtaining this polysaccharide, while conventional alkaline extraction methods dominate large-scale carrageenan production, greener lab-scale methods, such as enzyme-assisted extraction, show promise but face challenges regarding cost and scalability [33,81]. By operating in mild conditions with temperatures between 40 and 60 °C and pH being highly controlled, this type of extraction could cost time when used at an industrial scale.

On the other hand, microwave-assisted extraction (MAE) and ultra-sound-assisted extraction (UAE) reduce chemical usage, energy consumption and processing time enhancing the high demand of industry. MAE relies on intensify solvent penetration by heating the sample with dielectric frequency, facilitating cell wall disruption and releasing polysaccharides [82]. Notably, UAE efficiently yields higher quantities of carrageenan without altering its chemical structure [83,84,85], because UAE operates at frequencies typically between 20 and 40 kHz, promoting cavitation phenomena that disrupt cell walls and, as MAE, facilitates polysaccharide release [65].

However, the extraction method can influence the type of carrageenan obtained. Carrageenan is classified into two main grades based on extraction techniques: semi-refined carrageenan (SRC) and refined carrageenan (RC) [33]. The primary distinction lies in the content of acid-insoluble matter. SRC is produced through a simple alkaline extraction process, where the seaweed matrix is treated with potassium hydroxide (KOH) at approximately 75 °C for 2 h, resulting in the removal of soluble compounds such as salts, sugars, and proteins [9]. This process induces desulfation and increases the content of 3,6-anhydrogalactose. The potassium ions in the algae form a gel with carrageenan, preventing dissolution in hot solutions [86]. After treatment, the seaweed is washed, dried, and milled into powder, resulting in SRC, which is often colored and has higher bacterial loads, making it unsuitable for human consumption and primarily used in pet food [87]. Due to the retention of cell wall residues and higher microbial loads, SRC typically exhibits darker coloration, higher ash content, and reduced purity [88]. In contrast, RC undergoes a more rigorous extraction using hot alkaline solutions at higher temperatures (95–110 °C), along with additional purification steps such as filtration to remove residual cellulose and impurities [7]. Though RC, often termed crude carrageenan, is of superior quality, it involves higher costs due to precipitation and solvent recovery [87].

The residue remaining after carrageenan extraction, rich in glucans, can be hydrolyzed to obtain fermentable glucose, providing a basis for bioethanol production [3]. Employing advanced, eco-friendly methods like microwave- or ultrasound-assisted extraction can enable sequential recovery of these multiple high-added-value molecules, transforming K. alvarezii from a monoculture commodity source into a versatile, zero-waste marine bioplatform.

5. Gaps and Prospects

Among the 38 articles identified in the research, the Health/Medicine sector stood out, accounting for 29% of the studies. This was followed by Human Food (26%), General Industry (21%), Animal Nutrition (16%), and Agriculture (8%). As anticipated, a greater number of subcategories were observed in the more prominent sectors, with five applications focused on Health/Medicine, four in Human Food, three in General Industry, and two each for Animal Nutrition and Agriculture (Figure 5).

It is important to highlight that articles utilizing carrageenan in any biotechnological application, but not specifying its source, i.e., K. alvarezii, were excluded from the research criteria. Importantly, by searching the same database, i.e., the Capes Journals Portal and applying the same filter, i.e., only peer-reviewed articles published in English from 2010 to 2025, 11,315 manuscripts were found by using the term “carrageenan”. However, when the term “Kappaphycus alvarezii” was employed, this number drastically reduced to just 227, suggesting that many articles do not specify the biomass origin. Similarly, a search in the Scopus database returned 14,350 documents with the descriptor “carrageenan,” but this figure dropped to 264 when the descriptor was combined with “Kappaphycus alvarezii”. Despite a total of 491 manuscripts, 23 were excluded for failing to specify the biomass source, with K. alvarezii mentioned only in another part of the text (n = 32) or including articles that were entirely outside the scope (n = 156). Thus, at least 23 additional articles could have been included if they had detailed the source of the carrageenan, provided it was derived from K. alvarezii. This highlights an unforeseen gap in the initial research, as authors do not consistently indicate the source of the carrageenan utilized in their studies. Such omissions may limit the reproducibility of experiments, especially since different sources can yield varying amounts of specific types of carrageenan (kappa, iota, or lambda).

Another prominent gap is the lack of applications in other fields. While significant attention has been given to sectors such as Health/Medicine, Human Food, General Industry, Animal Nutrition, and Agriculture, areas like textiles and construction remain largely untapped. This presents an opportunity for further exploration and innovation, as these sectors could benefit from carrageenan’s unique properties. In the textile industry, for instance, the physicochemical properties of carrageenan enable its use in fiber production, serving as a promising renewable resource to replace synthetic fibers derived from petrochemicals. This makes it an environmentally friendly and biodegradable alternative. Its unique properties contribute to excellent inherent flame retardancy, which suggests significant potential for applications requiring high safety standards against fires, such as firefighter uniforms, military combat gear, and curtains [89,90,91]. In the construction sector, the thickening and gelling properties of carrageenan can function as an additive to modify flexural characteristics, resulting in high compressive strength, flexural resistance, and impact toughness [26]. Furthermore, its application may be particularly beneficial for reinforcing calcareous soils in marine construction, as sulfate groups can react with cationic metal ions in the soil, enhancing soil stability [92]. For both these sectors, κ-carrageenan, predominantly found in K. alvarezii, is especially desirable due to its robust properties and gel-forming capabilities.

In comparison to other compounds with similar functions or those derived from sources where κ-carrageenan is not the primary component, carrageenan extracted from K. alvarezii represents a natural alternative, constituting a sustainable and biodegradable choice over synthetic additives. This is particularly relevant in recent years as consumer demand for “green” products has increased [93]. Furthermore, the chemical composition of K. alvarezii is often more stable compared to other macroalgae, resulting in a more uniform carrageenan profile and yield [11]. The specific properties of this polysaccharide, primarily composed of κ-carrageenan, confer a range of functional properties such as gelling, thickening, and emulsifying, which, with refined extraction methods, allow its use in more specialized sectors like cosmetics and pharmaceuticals [94]. Lastly, the cultivation of K. alvarezii occurs rapidly in marine environments, enabling efficient year-round production across various countries. Additionally, its cultivation can contribute to mitigating environmental impacts [95].

The 38 articles identified and selected indicated that carrageenan was obtained specifically from K. alvarezii. However, eight articles did not clearly describe the biomass source. Among the 30 manuscripts describing the origin of K. alvarezii used for carrageenan extraction, it was found that 27 reported the use of biomass from K. alvarezii sourced from Asia, particularly Indonesia (n = 11), India (n = 9), Malaysia (n = 6), and the Philippines (n = 1). Three manuscripts were noted as originating from South America, specifically Brazil. This indicates that most research continues to be concentrated in Asia, which aligns with the massive production of that red macroalga species in that continent. Cai et al. [96] state that Asia has the highest number of Kappaphycus/Eucheuma-producing countries (n = 9), followed by countries or territories in East Africa (n = 4), Pacific Island states (n = 4), and Latin America and Caribbean (n = 6).

Indonesia, which has excelled in production, remains the leading country for the cultivation of Kappaphycus/Eucheuma, with 9,795,400 tons derived from the total production of 11,622,213 tons (wet weight) in 2019 [96]. In Indonesia, since seaweed farming is an important source of income for many coastal communities, the government has developed plans and strategies to expand cultivation and the processing industry [97]. In the same way, India is a country where K. alvarezii has provided diverse means of livelihood for low-income artisanal fishermen over the past 15 years. Moreover, this species is the only one that has maintained commercial cultivation in the last two decades. It is estimated that the cumulative commercial production of biomass from 2005 to 2020 reached 8088 tons (dry weight), with a farm gate value of $2,390,184, mainly as raw material for semi-refined and refined carrageenan [98].

Likewise, in Malaysia, seaweed cultivation has improved the socioeconomic conditions of local coastal communities by providing employment and income opportunities [99]. Malaysia is the third-largest producer in Asia, with 188,110 tons [96]. The Philippines, on the other hand, is the second-largest producer in Asia, with 1,498,788 tons in 2019 [96]. This high production is largely attributed to the significant diversity of cultivars maintained by Filipino farmers. A total of 66 cultivars has been registered across 58 provinces in the Philippines, owing particularly to the traditional knowledge of the farmers [100]. However, it is important to note that, as observed in India [98], Malaysia [99], and the Philippines [101], declines in production have been reported. This fact may be attributed to difficulties in producing healthy, vigorous seeds, as well as issues with diseases and climate change [98,99].

Latin America and the Caribbean have produced 874 tons, and Brazil is the leading producer with 700 tons [96], a significantly lower amount than Asia. However, the commercial cultivation of K. alvarezii in Brazil is quite recent, dating from 2020 and having been authorized only in three states located in the southern (Santa Catarina state) and southeastern regions (São Paulo and Rio de Janeiro states) of the country, respectively [102]. Given that production is still recent and limited compared to the Asian countries with well-established cultivation chains, the focus in Brazil has been on producing bio-stimulants/biofertilizers, driven by the substantial national demand from agribusiness. The value of these products is higher than the price paid by the carrageenan industry, and processing is more straightforward, allowing producers to process their biomass independently without relying on the international market [103]. Thus, the limited number of studies originating from Brazil can be attributed to such factors.

In general, carrageenan stands out as a versatile and valuable biopolymer with a wide range of applications in food, pharmaceuticals, and biotechnology, owing to its unique properties and bioactive potential. Ongoing advancements in extraction technologies are enhancing the sustainability of carrageenan production while broadening its applicability. By optimizing the utilization and extraction of K. alvarezii biomass and producing both semi-refined and refined grades, the marine biorefinery concept not only drives economic growth but also encourages eco-friendly practices.

6. Conclusions

This review demonstrates that carrageenan extracted from K. alvarezii can be applied across various industrial sectors. Notably, the Health/Medicine sector accounted for 29% of the research, followed by Human Food at 26% and General Industry at 21%. Specifically, in the Health/Medicine sector, carrageenan is utilized in scaffolds, antimicrobial agents, encapsulants, and wound dressings. In the Human Food sector, its primary applications include edible films and food additives. In Agriculture, carrageenan serves as an inducer of the plant’s defense mechanisms, while in the Aquaculture sector, it is applied in fish nutrition and livestock farming. Finally, in the General Industry, carrageenan is involved in developing biomaterials, bioproducts, and applications in biorefinery.

Overall, leveraging biotechnology to explore and further expand the applications of carrageenan derived from K. alvarezii has the potential to drive innovation, meet market demands, and support environmental sustainability. However, additional research across all sectors is critical to fully realize its potential. Furthermore, it is important to note that many studies may not have been included in this systematic review, as the authors often fail to specify the source of carrageenan.