The case for algae as a future food rests on striking numbers. Many species grow in marine, brackish, or otherwise non-arable environments and require little freshwater, while delivering areal productivities that dwarf conventional protein crops. According to the review, soybeans, pulses, and wheat yield roughly 0.6 to 1.2, 1 to 2, and 1.1 tons of protein per hectare per year, respectively, whereas microalgae can reach 4 to 15 tons and macroalgae 2.5 to 7.5 tons under favorable conditions. Certain species can accumulate more than 30 percent of their daily biomass as growth under optimal conditions. Arthrospira, the cyanobacterium sold as spirulina, can contain up to 60 percent protein by dry weight, and Chlorella vulgaris biomass may reach 51 to 58 percent protein alongside B vitamins, beta-glucan, and pigments. Global production of dried Arthrospira and Chlorella currently stands at an estimated 5,000 and 2,000 tonnes of dry matter per year, a combined market worth about 40 million US dollars annually.

The nutritional portfolio extends well beyond protein. The diatom Phaeodactylum tricornutum can devote 30 to 40 percent of its total fatty acids to eicosapentaenoic acid, while Schizochytrium limacinum allocates nearly half of its lipids to docosahexaenoic acid, the long-chain omega-3 fatty acids usually obtained from fish, which themselves acquire them from planktonic algae. Red algae such as Palmaria palmata and Porphyra purpurea reach protein contents of 20 and 30 percent of dry weight. Macroalgae also supply the hydrocolloids agar, alginate, and carrageenan, which the food industry relies on as thickeners, gelling agents, and stabilizers. Alginate can account for up to 40 percent of the dry weight of some brown algae, and carrageenan content in red seaweeds generally ranges from 15 to 50 percent, with kappa, iota, and lambda variants forming gels of very different strength and elasticity depending on sulfation and ions such as potassium and calcium.

Yet the same biology that makes algae productive also makes them difficult to eat. Rigid cell walls built from cellulose, alginate, ulvan, agar, or carrageenan lock nutrients away from human digestive enzymes. Marine off-flavors, driven largely by volatile sulfur compounds and lipid-oxidation aldehydes, suppress consumer acceptance, and green pigmentation limits the products algae can be added to without reformulation. Safety adds another layer of complexity: heavy metals, excessive iodine, arsenic species, and microbial contamination can accumulate during cultivation and processing. The review stresses that simply stirring algal powder into bread or pasta is not enough; fortification must be formulation-specific, balancing nutrient bioavailability, color stability, odor, and texture, because excessive addition quickly erodes consumer acceptance in mild-flavored or pale products.

Fermentation attacks several of these barriers at once. Microbes secrete extracellular proteases, peptidases, glycosidases, and carbohydrate-active enzymes that partially dismantle cell walls and convert insoluble macromolecules into soluble, digestible compounds. Cellulases hydrolyze cellulose into oligosaccharides and glucose, alginate lyases depolymerize alginate, and agarase- or carrageenase-producing bacteria degrade the sulfated galactans of red algae, although these activities are strongly strain-dependent. In one study cited by the review, combining alginate lyase with cellulase improved hydrolysis of the brown alga Laminaria japonica more than either enzyme alone. Proteolysis converts algal proteins into peptides and free amino acids, potentially improving digestibility and flavor; mixed fermentation of Porphyra yezoensis with Lactiplantibacillus plantarum, Bacillus amyloliquefaciens, and Saccharomyces cerevisiae promoted the formation of antioxidant peptides.

Lactic acid fermentation is the most food-ready option. Lactic acid bacteria, including Lactobacillus, Lacticaseibacillus, Lactococcus, Tetragenococcus, and Weissella, acidify the substrate, inhibit spoilage and pathogenic organisms, and generate aroma-active metabolites. Quantified examples show real conversion efficiency: after acid-thermal hydrolysis, Gracilaria sp. yielded 0.39 grams of reducing sugar per gram of biomass and a lactic acid yield of 0.94 grams per gram, with corresponding yields of 0.85 for Ulva sp. and 0.81 for Sargassum cristaefolium. Fermentation of the brown alga Alaria esculenta by a lactic acid bacterial consortium dropped the pH to about 3.8 within seven days, with the microbes consuming glucose, mannitol, and laminari-oligosaccharides to produce lactic acid, ethanol, and succinate. Lactic acid itself has value beyond preservation, serving as a precursor for polylactic acid, a biodegradable alternative to petroleum-based plastics.

Yeasts excel at the sensory side of the problem. Fermenting Saccharina japonica seedlings with Saccharomyces cerevisiae substantially changed the volatile profile, and compounds tied to fishy odors, including 1-octen-3-ol and hexanal, were reduced. Fermentation of Bangia fusco-purpurea with the same yeast reduced or eliminated several odor-active compounds, including hexanal, nonenal, 2-pentylfuran, and unsaturated aldehydes. Yeast fermentation of seaweed extracts with L. plantarum also increased bile-acid-binding capacity and pancreatic-lipase-inhibitory activity in vitro and showed beneficial effects in a hyperlipidemic mouse model, though the review cautions that such biological effects depend on strain, substrate, and processing and cannot be generalized. A key limitation remains: conventional S. cerevisiae strains efficiently consume glucose but poorly utilize alginate and other unusual brown-algal carbohydrates, so enzymatic pretreatment, adaptive evolution, metabolic engineering, or co-culture with polysaccharide-degrading bacteria may be required.

Mixed-culture fermentation may offer the best of all worlds, but also the hardest process control. Filamentous fungi secrete copious extracellular enzymes that degrade algal cell walls, preparing the substrate for lactic acid bacteria whose acid production then suppresses undesirable microbes and creates conditions favorable for yeast inoculation. During alcoholic fermentation, yeast-derived ethanol reacts with bacterial organic acids to form esters, while higher alcohols, aldehydes, and ketones add sensory complexity. The review’s comparison tables, however, make clear that every microbial option carries trade-offs. Bacillus species show strong proteolytic and alginate-degrading capacity but risk generating bitterness, ammonia, or biogenic amines such as histamine and tyramine. Filamentous fungi offer the broadest enzymatic repertoire but demand strict strain authentication and mycotoxin monitoring. Decarboxylase-positive lactic acid bacteria can convert algal free amino acids into biogenic amines, and uncontrolled mold growth in solid-state fermentation can produce mycotoxins.

The authors are equally candid about industrial bottlenecks. Large-scale microalgal production remains far below that of staple crops like wheat, limiting algae’s competitiveness as a bulk ingredient and favoring its use as a high-value functional additive. Conventional extraction is energy-intensive, slow, and solvent-hungry; algal hydrolysates may contain fermentation inhibitors requiring detoxification; and efficient enzymes for complex algal polysaccharides remain scarce. Biomass composition varies with species, season, harvest time, and post-harvest handling, altering protein, carbohydrate, lipid, ash, salt, and moisture contents and thus fermentation performance. At scale, reactors must manage mixing, oxygen and heat transfer, pH, viscosity, and contamination, and the review insists that feasibility be judged with pilot-scale data, realistic yields, and integrated techno-economic and life-cycle assessments. It also warns explicitly that fermentation should not be assumed to remove heavy metals, iodine, or other chemical contaminants, so species-specific monitoring and final-product testing remain necessary.

The path forward, the review concludes, lies in a cascading biorefinery: recover high-value proteins, pigments, lipids, and polyphenols first, then ferment the remaining carbohydrate- and protein-rich fractions into organic acids, alcohols, peptides, and aroma compounds, and direct residual solids toward feed, anaerobic digestion, biochar, or soil amendments where safety permits. Most edible algae have never been systematically domesticated, so clarifying life cycles, ploidy regulation, and reproductive triggers could enable breeding for higher yields, better digestibility, and reduced off-flavors, with the model organism Chlamydomonas reinhardtii serving as a platform for trait discovery. Broader safety assessments to support regulatory approval and GRAS recognition, strain improvement through breeding or engineering, and sensory optimization using electronic-tongue screening and human panels round out the priorities. On that coordinated foundation, the authors argue, algae could graduate from niche supplements to safe, palatable, multifunctional ingredients within sustainable food systems.

Subject of Research: Fermentation-based valorization of edible algae for sustainable food applications

Article Title: Fermentative valorization of edible algae: nutritional potential, food applications, safety considerations, and industrial challenges

Article References: Ma, D., Xia, C., Jia, A., Zhang, G., Zhao, Y., Ren, H., Liu, X., Li, F., Li, L., Jia, R., & Li, K. (2026). Fermentative valorization of edible algae: nutritional potential, food applications, safety considerations, and industrial challenges. Frontiers in Microbiology, 17, Article 1966638. https://doi.org/10.3389/fmicb.2026.1966638

Image Credits: AI Generated

DOI: 10.3389/fmicb.2026.1966638

Keywords: edible algae, fermentation, microalgae, macroalgae, lactic acid bacteria, food safety, functional foods, cell-wall disruption, biorefinery, sustainable food systems, sensory quality, polyunsaturated fatty acids