Introduction
The need for dietary protein is increasing rapidly due to the expanding world population. Algae have gained popularity as a potential food source because of their high-value constituents, such as proteins, and environmental sustainability. However, the current understanding of food applications and dietary guidelines limits the use of algae as a possible source of protein.
What Is Algae?
Algae are a broad group of photosynthetic eukaryotic organisms. They include unicellular, microscopic, and complex macroalgae, also known as seaweed. Algae are more profitable, grow faster, and produce more protein than most terrestrial plants, making them a more reliable source of protein. Algae farming is resource-efficient in the agri-food system and does not compete with standard food sources for arable land and potable water. Algae can be grown in various settings, including lakes, oceans, and regulated photobioreactors.
They can be grown heterotrophically with minimal carbon sources or carbon-neutral photoautotrophically. This means algae cultivation has a lesser environmental impact than traditional protein sources. The ability of the algae to produce high-value organic compounds or biofuel through CO3 biofixation and industrial CO2 rapping, as well as reducing greenhouse gas emissions, has been investigated as part of the marine circular economy strategy. Algae are, therefore, a highly desirable substitute for traditional protein sources due to their versatility, which goes beyond their use in food production.
What Are the Types of Algae?
Algae are broadly classified into microalgae and macroalgae and are further divided into three types based on their pigments:
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Green seaweeds (chlorophytes).
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Brown seaweed (phaeophytes).
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Red seaweed (rhodophytes).
Cyanobacteria are commonly referred to as blue-green algae.
1) Macroalgae:
Green seaweeds, brown seaweeds, and red seaweeds are the three types.
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Green Seaweeds (Chlorophytes): Green seaweeds include sea lettuce and sea grapes and are recognized for their bright green color and rich protein content. Sea grapes, also known as umibudo, are a popular edible green seaweed in Southeast Asian and Japanese cuisine, and sea lettuce is usually included in salads and soups.
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Brown Seaweeds (Phaeophytes): Brown seaweeds have various varieties, such as wakame, arame, hijiki, kombu or konbu, and kelp. Wakama is a common brown seaweed found in Asian cuisine, and it is known for its soft texture and mild flavor. Japanese cuisine also frequently uses amazing hijiki in various dishes for its unique flavor and texture. Kelp has a variety of functional and nutritional qualities due to its huge size and high alginate, fucoxanthin, and fucoidan content concentrations. Cochayuyo and kombu are well-known edible kelps. Japanese cooking frequently uses kombu for its unique umami flavor.
- Red Seaweeds (Rhodophytes): Red seaweed comprises edible seaweeds like Irish moss, dulse, nori, or laver. Nori is commonly used in sushi rolls. Dulse grows in cool Arctic conditions, is known for its unique flavor, and is frequently used in soups, salads, and snacks. Carrageen, or Irish moss, is a common thickening ingredient in food products. Phycoerythrin is one of the specific pigments that make red seaweeds valuable.
2) Microalgae:
Microalgae are unicellular photosynthetic organisms that have gained popularity as dietary supplements and provide a variety of nutritional advantages. Edible species include Aphanizomenon flos-aquae, spirulina, and chlorella. Tetraselmis, Isochrysis, and Nannochloropsis are other species suitable for commercialization for human consumption. Each species has a different nutritional profile and set of advantages. They are usually taken as pills or powder supplements, with daily doses varying from 1 to 5 grams.
Arthrospira, sometimes called spirulina, was used by the Aztecs to increase capacity. The commercial term spirulina is still applied to edible Arthrospira species, such as A.Platensis and A. maxima. It is considered a superfood high in vitamins, minerals, and protein, making it the perfect nutritional supplement for vegans or vegetarians.
What Are the Nutritional Contents of Algae?
Algae are rich sources of dietary fiber, vital minerals like iron, calcium, magnesium, and potassium, and ω-3 and ω-6 fatty acids, as well as vitamins A, C, D, E, K, and B. Algae have rich nutritional profiles, but they also have primary metabolites such as phycobiliproteins and polysaccharides that can improve the rheological and nutritional properties of food.
Algae also include secondary metabolites, such as xanthophylls and polyphenols, which have bioactive and antioxidant characteristics. All nine essential amino acids (EAA) are abundant in microalgae, with species including C. vulgaris, C. pyrenoidosa, A. platensis, and A. maxima possessing 50 to 70% protein by dry weight. Because of this, algae are now considered valuable protein sources in equal amounts, with proteins originating from animals. The protein content of green seaweeds ranges from 4.6 to 32.2% dry weight in the 5th to 95th percentile, red seaweeds from 2.0 to 28.7% dry weight, and brown seaweeds from 3.3 to 15.9% dry weight.
What Are the Health Benefits of Algae?
Consumption of algae reduces inflammation and improves gut health. Spirulina has high γ-linolenic acid, protein, and fiber content and is specifically responsible for its favorable effect on lipid metabolism. γ-linolenic acid prevents fat and cholesterol from accumulating within the body. The protein and fiber content in spirulina reduces the generation of VLDL (very low-density lipoprotein) and TG (triglycerides).
It encourages VLDL clearance in the periphery, which reduces TG and VLDL following spirulina consumption. Human poisoning incidents with the intake of wild-harvested spirulina containing Microcystis and other freshwater cyanobacteria that produce hepatotoxins and neurotoxins are widely reported. This indicates the need to create regulated, large-scale cultivation and ongoing testing of potential supplement crops.
Conclusion
Algae’s nutritional content, health benefits, and physiochemical qualities suit a variety of food-related uses and contribute to a potential food source. More multidisciplinary research is required, but the potential for integrating algae into the food chain is immense. Future research should prioritize the adaptability of techniques for extracting proteins and nutrients and localizing algae production, emphasizing lifecycle studies, affordability, and sustainability.
