Search Results (62)

Utilizing biomass resources to develop carbon-based microwave-absorbing materials adheres to the principles of sustainable development. Nevertheless, the single loss mechanism of pure carbon materials is limited. Additionally, the carbonization of artificially synthesized polymers has poor environmental performance and involves complex processes. These issues restrict their performance and broader applicability. In this study, cobalt-doped seaweed sludge porous carbon (Co/SSPC) with different cobalt contents was synthesized via a simple grinding–carbonization treatment. The addition of cobalt can regulate the graphitization degree of porous carbon, achieving a suitable amorphous-to-crystalline carbon ratio of 2.05. This not only enhances magnetic loss but also modifies dielectric loss and optimizes impedance matching. The construction of synergistic magnetic and dielectric loss mechanisms enables Co/SSPC to exhibit excellent microwave absorption performance. Specifically, Co/SSPC achieved a minimum reflection loss (RL_min) of −66.91 dB at a thickness of 4.79 mm and an effective absorption bandwidth (EAB) of 5.09 GHz at a thickness of 1.6 mm. This study provides a practical approach for the functional application of natural polymer waste algal sludge and highlights its potential in the low-cost production of microwave absorbing materials. Full article

Kelp (Laminaria japonica) is renowned for its rich content of flavor-enhancing amino acids and nucleotides; however, approximately 40% of kelp, including the thin edges and root areas, is discarded during its processing due to its inferior taste. To recycle these kelp byproducts, we have cultivated a functional microbial consortium through continuous enrichment. Analysis via 16S rRNA sequencing has shown that during the three fed-batch fermentation stages of kelp waste, the microbial community was predominantly and consistently composed of three phyla: Halanaerobiaeota, Bacteroidota, and Proteobacteria. At the genus level, Halanaerobium emerged as the dominant player, exhibiting a trend of initial increase followed by a decline throughout the fermentation process. Enzymes such as alginate lyases and both acidic and neutral proteases were found to play crucial roles in the degradation of kelp residues into sauces. Notably, electronic tongue analysis revealed that the fermented kelp sauce demonstrated strong umami characteristics. Furthermore, four novel umami peptides, EIL, STEV, GEEE, and SMEAVEA, from kelp were identified for the first time, with their umami effect largely attributed to strong hydrogen bond interactions with the T1R1–T1R3 umami receptors. In conclusion, this study proposed a sustainable method for kelp by-product utilization, with implications for other seaweed processing. Full article

Microplastics (MPs), defined as plastic particles smaller than 5 mm, have emerged as a global environmental and public health crisis, infiltrating air, water, soil, and food systems worldwide. MPs originate from the breakdown of larger plastic debris, single-use plastics, and industrial processes, entering food. Emerging evidence underscores the ability of MPs to cross biological barriers, including the blood–brain barrier, triggering neuroinflammatory responses and contributing to neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Polystyrene (PS), a common type of MP, activates microglial cells, releasing pro-inflammatory cytokines like tumor necrosis factor (TNF-α) and interleukins, which increase neuronal damage. MPs have also been linked to cardiovascular diseases, with studies detecting polyethylene (PE) and polyvinyl chloride (PVC) in carotid artery plaques, increasing the risk of myocardial infarction and stroke. Furthermore, MPs disrupt endocrine function, alter lipid metabolism, and induce gut microbiome imbalances, posing multifaceted health risks. In the MENA region, MP pollution is particularly severe, with the Mediterranean Sea receiving an estimated 570,000 tons of plastic annually, equivalent to 33,800 plastic bottles per minute. Studies in Egypt, Lebanon, and Tunisia document high MP concentrations in marine ecosystems, with herbivorous fish like Siganus rivulatus containing over 1000 MPs per individual due to the ingestion of contaminated seaweed. Despite these findings, public awareness and regulatory frameworks remain inadequate, with only 24% of Egyptians demonstrating sufficient knowledge of safe plastic use. This review emphasizes the urgent need for region-specific research, policy interventions, and public awareness campaigns to address MP pollution. Recommendations include sustainable waste management practices, the promotion of biodegradable alternatives, and enhanced monitoring systems to mitigate the health and environmental impacts of MPs in the MENA region. Full article

According to the Sustainable Blue Economy Communication, the Farm to Fork Strategy, and the European Green Deal, novel business models supporting the use of resources from oceans and seas are of primary importance. Interestingly, several infesting seaweeds are consumed as foods in Asia and are fundamental ingredients in several traditional dishes. Herein, according to the circular economy approach, we investigate the use of Chaetomorpha linum (CL) as a Tenebrio molitor larvae feed in different percentages: 20%, 50%, and 100%, respectively. We analyzed the effects of CL on the survival and biometric parameters of larvae. The survival rate remained comparable to the control, while the mean weight was inversely proportional to the CL%. The nutrient composition was substantially different from the control, showing increased protein and reduced fat content. Analysis of the secondary metabolites revealed a better fatty acid composition, rich in PUFA, with lipid nutritional indexes comparable to seaweeds and crabs. The simulated gastrointestinal digestion highlights the increased content of essential amino acids, and a two times higher antioxidant activity with respect to the control. Taken together, our results confirm that CL can be used as a TML supplement, with beneficial effects in protein content and fat quality. Full article

Seaweed is a valuable natural resource, but drift or beach-cast seaweed is considered a waste product. Although seaweed is traditionally used as an organic amendment, vermicomposting has the potential to transform the material into valuable organic fertilizer, thereby enhancing its microbial properties. This study aimed to investigate the dynamics of the taxonomic and functional bacterial communities in seaweed during the vermicomposting process by high-throughput sequencing of 16S rRNA gene amplicons. Vermicomposting changed the composition of the bacterial communities, as indicated by the low proportion of bacterial taxa common to the bacterial communities in the raw seaweed and vermicompost (21 to 56 ASVs from more than 900 ASVs per sample type). The observed increase in taxonomic diversity (32% mean increase across sampling times) also affected the functionality of the bacterial communities present in the vermicompost. The diverse bacterial community showed enriched functional pathways related to soil health and plant growth, including the synthesis of antibiotics, amino acids, and phytohormones, as well as the degradation of bisphenol. In conclusion, in terms of microbial load and diversity, vermicompost derived from seaweed is a more valuable organic fertiliser than seaweed itself. Full article

The increasing levels of atmospheric carbon dioxide (CO₂) and plastic waste in marine environments demand immediate action to mitigate their effects. A promising solution lies in enhancing algal cultivation in marine environments, which not only absorbs CO₂ and produces oxygen (O₂) but also contributes to carbon sequestration. This study aims to develop biodegradable substrates for algae cultivation, facilitating their gradual degradation in marine environments and eventual deposition on the ocean floor, thereby addressing both plastic pollution and CO₂ emissions. We selected various degradable polymers and incorporated differing proportions of algae residue powder (10%, 20%, and 30% by weight) into these substrates. The compositions were processed through extrusion and molded into test samples for hot compression molding. Characterization included assessments of mass loss, morphology, chemical composition, and mechanical strength under both dry conditions and after immersion in seawater for up to two months. The results indicate that the incorporation of algae residue significantly accelerates the degradation of the samples, particularly under extended exposure to seawater. Mass loss measurements indicated that samples with a 30 wt% algae addition experienced mass losses of up to 12% after two months of immersion. Mechanical strength tests demonstrated a reduction of up to 57% in strength due to the incorporation of algae, with seawater immersion further exacerbating this loss. These findings highlight the potential of biopolymer substrates infused with algae residue for effective carbon sequestration through enhanced algae cultivation. Full article

This review evaluates regenerative aquaculture (RA) technologies and practices as viable pathways to foster resilient, ecologically restorative aquaculture systems. The key RA technologies examined include modern periphyton technology (PPT), biofloc technology (BFT), integrated multitrophic aquaculture (IMTA), and alternative feed sources like microalgae and insect-based diets. PPT and BFT leverage microbial pathways to enhance water quality, nutrient cycling, and fish growth while reducing environmental pollutants and reliance on conventional feed. IMTA integrates species from various trophic levels, such as seaweeds and bivalves, to recycle waste and improve ecosystem health, contributing to nutrient balance and reducing environmental impact. Microalgae and insect-based feeds present sustainable alternatives to fishmeal, promoting circular resource use and alleviating pressure on wild fish stocks. Beyond these technologies, RA emphasizes sustainable practices to maintain fish health without antibiotics or hormones. Improved disease monitoring programs, avoidance of unprocessed animal by-products, and the use of generally recognized as safe (GRAS) substances, such as essential oils, are highlighted for their role in disease prevention and immune support. Probiotics are also discussed as beneficial microbial supplements that enhance fish health by promoting gut microbiota balance and inhibiting harmful pathogens. This review, therefore, marks an important and essential step in examining the interconnectedness between technology, agroecology, and sustainable aquaculture. This review was based on an extensive search of scientific databases to retrieve relevant literature. Full article

Sea mustard (Undaria pinnatifida) is a brown macroalga extensively cultivated and consumed in South Korea. However, the high volume of seaweed production in the country results in substantial waste generation. To mitigate this issue, the bioactive compounds of sea mustard waste parts (sporophyll, root, and stem) were assessed under different drying conditions (freeze, oven, and microwave drying) to evaluate their potential as functional ingredients. The sporophyll contained the highest levels of total chlorophyll (540.38 μg/g), fucoxanthin (165.87 μg/g), flavonoids (5.47 μg QE/g), phytomenadione (332.59 μg/100 g), and cobalamin (5.92 μg/100 g). In contrast, the root exhibited the highest antioxidant activities (DPPH: 1582.37 μg GAE/g; ABTS: 0.93 mg AAE/g), total polyphenol (2718.81 μg GAE/g) and phlorotannin (4298.22 μg PGE/g) contents. Freeze drying achieved the best retention rates for most bioactive compounds, except for fucoxanthin, which was highest in microwave-dried samples. These results demonstrate the potential of sea mustard waste as a valuable source of bioactive compounds, with the retention of these compounds being influenced by drying methods, depending on the specific part of the seaweed. Full article

Whey is the largest waste product of the cheese-making industry and the current methods of extracting the nutrients from it are costly and inefficient. This study assessed the feasibility of using crude polysaccharides to flocculate proteins from liquid whey waste. The flocculants used were a sugar kelp (Saccharina latissima) extract, as well as commercial seaweed polysaccharides, alginate and k-carrageenan, to recover proteins from the liquid whey waste. Physicochemical and functional parameters including protein content, protein recovery efficiency, mineral content, total phenolic content (TPC), antioxidant capacity, color, water- and oil-holding capacity, gelling capacity, foaming activity and stability, and emulsifying activity and stability were tested on the resulting flocculates. The yield of the dried flocculates by use of alginate, the sugar kelp polysaccharide extract (SKPE), and carrageenan were 1.66, 0.98, and 1.22 g/100 g of liquid whey with protein contents of 27.4%, 45.5%, and 37.5%, respectively. The protein recovery efficiency from the whey was 57.5%, 56.2%, and 57.9% using alginate, SKPE, and carrageenan, respectively. The alginate flocculate had the highest oil-holding capacity and foaming abilities while the carrageenan flocculate had the best gelling ability and the highest emulsifying activity and stability. TPC and antioxidant activity were highest in the SKPE flocculate. All three flocculates presented slightly different compositional and functional qualities, which could be used for a variety of products. This study showed that seaweed polysaccharides present a simple and effective way to extract protein from liquid whey waste while creating a functional and high-protein ingredient. Full article

Carrageenans are valuable marine polysaccharides derived from specific species of red seaweed (Rhodophyta) widely used as thickening and stabilizing agents across various industries. Kappaphycus alvarezii, predominantly cultivated in tropical countries, is the primary source of kappa-carrageenan. Traditional industrial extraction methods involve alkaline treatment for up to three hours followed by heating, which is inefficient and generates substantial waste. Thus, developing improved extraction techniques would be helpful for enhancing efficiency and reducing environmental impacts, solvent costs, energy consumption, and the required processing time. In this study, we explored innovative extraction methods, such as ultrasound-assisted extraction (UAE) and supercritical water extraction (SFE), together with other extraction methods to produce kappa-carrageenan from a new strain of K. alvarezii from the Philippines. FTIR-ATR spectroscopy was employed to characterize the structure of the different carrageenan fractions. We also examined the physicochemical properties of isolated phycocolloids, including viscosity, and the content of fatty acids, proteins, and carbohydrates. For refined carrageenan (RC), both the traditional extraction method and the UAE method used 1 M NaOH. Additionally, UAE (8% KOH) was employed to produce semi-refined carrageenan (SRC). UAE (8% KOH) produced a high yield of carrageenan, in half the extraction time (extraction yield: 76.70 ± 1.44), and improved carrageenan viscosity (658.7 cP), making this technique highly promising for industrial scaling up. On the other hand, SFE also yielded a significant amount of carrageenan, but the resulting product had the lowest viscosity and an acidic pH, posing safety concerns as classified by the EFSA’s re-evaluation of carrageenan as a food additive. Full article

This article presents an efficient method for isolating cellulose nanocrystals (CNcs) from seaweed waste using a combination of electron beam (E-beam) irradiation and acid hydrolysis. This approach not only reduces the chemical consumption and processing time, but also improves the crystallinity and yield of the CNcs. The isolated CNcs were then thermally annealed at 800 and 1000 °C to produce porous nanocarbon materials, which were characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy to assess their structural and chemical properties. Electrochemical testing of electrical double-layer capacitors demonstrated that nanocarbon materials derived from seaweed waste-derived CNcs annealed at 1000 exhibited superior capacitance and stability. This performance is attributed to the formation of a highly ordered graphitic structure with a mesoporous architecture, which facilitates efficient ion transport and enhanced electrolyte accessibility. These findings underscore the potential of seaweed waste-derived nanocarbon as a sustainable and high-performance material for energy storage applications, offering a promising alternative to conventional carbon sources. Full article

Plastic food packaging causes massive pollution in the environment via resource extraction, gas emissions, and the enduring plastic waste accumulation. Hence, it is of crucial importance to discover sustainable alternatives in order to protect ecosystems and conserve precious resources. Recently, seaweed has been emerging as a promising sustainable solution to plastic pollution. Seaweed is a fast-growing marine plant that is abundant in tropical coastlines and requires minimal resources to cultivate. In addition, seaweed is rich in valuable polysaccharides such as alginate, fucoidan, carrageenan, agar, and ulva, which can be extracted and processed into biodegradable films, coatings, and wraps. This ability allows the creation of an alternative to plastic food packages that are completely biodegradable, made from renewable resources, and do not linger in landfills or oceans for centuries. In this context, this review discusses the main classification of seaweed, their production and abundance in the world, and provides a summary of seaweed-based materials developed in the last 2–5 years for potential usage in the food packaging sector. Full article

This study explored the development of hierarchical graphitic carbon structures (HGCs) from harmful inedible seaweed waste harvested in the summer. Elevated sea temperatures during the summer increase the cellulose content of seaweeds, making them unsuitable for consumption. By utilizing seaweed biomass, this study addresses critical marine environmental issues and provides a sustainable solution for promising electrode materials for energy storage devices. The fabrication process involved impregnating seaweed with Ni ions, followed by annealing to create a highly crystalline carbon structure. Subsequent etching produced numerous nano-sized pores and a large surface area (806 m²/g), significantly enhancing the number of electrically active sites. The resulting HGCs exhibited a high capacitance and maintained their capacity even after 10,000 cycles in fast-current systems. This innovative approach not only mitigates the environmental burden of seaweed waste but also offers a sustainable method for converting it into efficient energy storage materials. Full article

Sargassum fusiforme and Sargassum fulvellum are types of brown algae used for their nutritional value and medicinal properties, including anti-inflammatory, antioxidant, and anticancer effects. Despite their importance in various industries, many seaweed byproducts containing dietary fiber and polysaccharides are discarded in landfills. These byproducts can be recycled and repurposed for different applications. In this study, we investigated the impact of S. fusiforme food processing byproducts (MbP-SFF) and S. fulvellum food processing byproducts (MbP-SFV) on improving intestinal motility and reducing inflammation in mice with constipation induced by loperamide. To evaluate this, mice were orally administered 500 mg/kg/day of the byproducts once daily for 8 days. Constipation was induced by 5 mg/kg/day of loperamide for two days after oral administration for 6 days. Each sample contained approximately 70% carbohydrates. MbP-SFF had 52.0% mannuronic acid and 18.8% guluronic acid, while MbP-SFV had 36.9% mannuronic acid and 32.9% guluronic acid. These byproducts enhanced fecal excretion and intestinal motility by modulating inflammatory responses. Furthermore, they restored the balance of the gut microbiota disrupted by loperamide, increasing beneficial Bifidobacterium and reducing harmful Staphylococcus aureus. Overall, MbP-SFF and MbP-SFV improved intestinal motility and inflammation by influencing the gut microbiota and inflammatory responses in a loperamide-induced mouse model. These byproducts show potential as ingredients in functional foods aimed at enhancing gut health, potentially reducing waste disposal costs and addressing environmental concerns associated with their utilization. Full article

The increasing invasion of Rugulopteryx okamurae algae along the coast of southeastern Spain has prompted efforts to explore its potential as a resource. Consequently, composting this alga is considered a viable solution for agricultural applications. This study investigates the composting process of mixtures of R. okamurae seaweed with plant residues and characterizes the final compost for its use as a substrate and/or source of nutrients to determine the most effective composition of the mixture. The composting process was conducted using varying proportions of seaweed (100%, 30–35%, and 15%) combined with plant residues (from vegetable plants, fruits, and gardens) and included both washed and unwashed seaweed. The first trials revealed challenges associated with Rugulopteryx okamurae, such as a low C/N ratio and algae washing. Consequently, a second trial was conducted to optimize the mixtures, aiming for a C/N ratio close to 30. Additionally, it was decided not to wash the algae to reduce the electrical conductivity (EC) in the mixtures. The findings indicate that the composting process remains unaffected by high electrical conductivity when algae are unwashed. However, washing the algae before composting did affect the compost quality, as the composts with washed algae with garden waste (S_wP 34.0 dS m⁻¹) had a lower electrical conductivity (EC) than did the unwashed composts with garden waste (SP 51.6 dS m⁻¹ and SFP 64.9 dS m⁻¹). On the other hand, the compost-only horticultural and garden waste (FHP 43.7 dS m⁻¹) had a high EC; therefore, the EC was not increased with low proportions of unwashed algae, as was seen with the compost with 15% unwashed algae (SFHP 47.6 dS m⁻¹). The other quality parameters were not affected by the absence of algae washing at the beginning of the composting process. Full article