Sea weeds are nothing but marine algae which are also known as macroalgae. It belongs to a quite ill-defined assemblage of plants known as algae. The algae lack true roots, stem, leaves, and vascular tissues which make them differ from higher plants. Seaweeds or macroalgae can be classified into three major groups, Red algae (rhodophyta), green algae (chlorophyta), brown algae (phaeophyta), and blue-green algae(cyanophyta). Depending on the organisms, collection time and environment, and environmental factors such as water temperature, light intensity, and water nutrient concentration, they have a highly variable composition.
Types of Seaweeds
Red algae have a distinctive bright pink coloring due to the presence of biloprotein pigments (R-phycoerythrin and R-phycocyanin). There are large genera of red algae including Pyropia, Porphyra, Chondrus, and Palmaria. Pyropia and Porphyra are the largest sources of food from red algae. Palmariapalmate is another red algae which is rich in protein and harvested for food. It is also fed to cattle, sheep, and goats.
Green algae usually have a green color due to the obvious presence of chlorophyll in their chloroplast. The overall coloring of the algae depends on the balance between the chlorophylls and other pigments like beta-carotene and xanthophylls. And they are commonly found in light abundant areas. Ulva, Codium, Enteromorpha, Chaetomorpha, and Cladophora are the large genera of green algae.
Ulva species are usually referred to as sea lettuce, because of their small and bright green fronds. Ulvoids, which include Ulva and related genera (Enteromorpha, Chaetomorpha, Cladophora, Rhizoclonium, Percursaria, Ulvaria) are algae of rapid growth. All Ulva species are edible and Ulvalactuca is also called water lettuce.
Brown seaweeds are the largest seaweeds with extremely variable shapes and some with a length of 35-45m and are easy to harvest. it is used as an animal feed. Ascophyllum, Laminaria, Saccharina, Macrocystis, Nereocystis, and Sargassum are the most common genera of brown algae.
Ascophyllumnodosum is harvested for the production of fertilizer, feed, and alginate. Saccharinalatissima, Laminariahyperboreand Laminariadigitata has a long history of use in livestock feed. These are also used for alginate, food, and feed production.
Macrocystispyrifera which is also known as giant kelp is reaped for the production of animal feeds, pharmaceutical additives, and alginate. Brown algae are of minor nutritional value than green and red algae due to the lower protein content and higher mineral content.
Blue Green Algae
The blue-green algae are also called cyanobacteria show many structural features that resemble bacteria, but they are classified as algae because of the presence of chlorophyll and related compounds. Spirulina is a type of cyanobacteria or blue-green algae that can be consumed by animals and humans.
Here are few common edible sea weeds:
Carrageenans a linear sulfated polysaccharide extracted from edible red algae. These are also called Irish moss. It acts as a thickening and emulsifying agent in food and drinks. It is used as an additive in dairy products to preserve food and drinks. This is a vegan alternative to replace gelatin in confectionaries.
They are present in toothpaste, shampoo, diet soda, soy milk, beer, sauces, and confectionaries, etc. Some studies show that the carrageenan cause bloating, inflammation, food allergies, glucose intolerance, etc.
Chlorella is green algae which can be used as a healthy food source due to its high protein content and the presence of other essential nutrients. Research suggests that chlorella helps in the removal of heavy metals from the body and it also boosts the body’s immune system.
The carotenoids lutein and zeaxanthin present in the chlorella indicates its beneficial effect on eye health. The health benefits of chlorella include helping with conditions like stomach ulcers, wounds, constipation, anemia, hypertension, diabetes, infant malnutrition, and neurosis. It can also be used as a natural coloring agent.
Oils rich in polyunsaturated fats can be made from chlorella. Solazyme and allma are commercially available chlorella products manufactured by companies. The consumption of chlorella can cause nausea and discomfort in the abdomen in some individuals.
Hijiki belongs to the brown algae group which is a common ingredient in Japanese cuisine. During harvesting, it is in dark green to brown in color and after the boiling and drying process, the color turns black. The dried hijiki is a good source of dietary fiber and also minerals like calcium, magnesium, iron, iodine, and vitamin K. Hijiki is soaked before cooking and then cooked with soya sauce and sugar.
The Korean name of hijiki is tot. Eating hijiki can improve hair growth, maintain blood glucose levels. Studies suggest that hijiki contains a high amount of arsenic which leads to an increased incidence of cancer. So it is advisable to consume hijiki occasionally.
Kombu is edible kelp which is also called Dasima and Haidai. In particular, Kombu kelp, unlike any other seaweed, has a flavor and nutritional value, earning it the nickname–”the king of seaweed.” It is the main ingredient for making dashi( a soup stock with umami taste)Kombuis rich in nutrients including calcium, vitamins, and dietary fiber. It is also a good source of iodine.
It is a good source of glutamic acid. Konbu-cha or kobu-cha is a tea made by infusing kombu in hot water. The dishes made of Kombu include tsukudani, sashimi, oden, nimono, kombu roll. Kombu is either picked in vinegar, sold dried or dried shred.
Nori is the Japanese name for red seaweed of the genus Porphyra, it is also called as Gim in Korean and Zicai in Chinese. It is abundant in vitamin A, thiamine, riboflavin, vitamin B6, B12, and the minerals iron and iodine. In fact, it is the only vegetarian source of vitamin B12. It is also a good source of protein and heart-protecting omega 3 fatty acids.
The soluble fiber present in gim helps to lower the LDL cholesterol and the amino acids aids in good digestion. The red seaweed Nori is used for the traditional wrapping of sushi or onigiri in Japanese cuisine and eaten in soups. Koreans use this gim to make gimbap and banchan.
Ogonori is also known as ogo or sea moss belongs to the genus Gracilaria of red algae. it is used as food in Japanese, Filipino and Hawaiian cuisine. It is called gulaman in Phillipines and is used to make gelatin. this is the source of agar-agar. It is a good source of dietary fiber, iron, iodine, vitamin C; the health benefits of ogonori include improved thyroid function, regular bowel movement, boost immunity, reduced inflammation, and optimal RBC count.
Spirulina is a cyanobacteria often referred to as non-toxic blue-green algae. it is considered as a nutrient-dense food that is not toxic and has anticancer, antiviral, immune properties, and it also acts as a powerful antioxidant. It is a good source of protein, B vitamins, and minerals.
The essential amino acid phenylalanine is present in spirulina, so should be avoided by people with phenylketonuria. It is a source of bioactive compoundphycocyanobilin. This compound is a close homolog of bilirubin in the body and inhibits the NADPH oxidase (an enzyme complex). By inhibiting this enzyme complex spirulina provides promising anti-oxidant and anti-inflammatory effects. Studies suggest that spirulina can decrease LDL cholesterol and raise the level of HDL cholesterol.
Ulva is also known as sea lettuce or water lettuce is thin flat green algae. it is used to prepare salads and soups. It is a good source of nutrients including proteins, amino acids, vitamins, and minerals. Ulva comprises phenolic, chlorophyll, and carotenoids which can be called free-radical active scavengers and exhibit antioxidant properties.
Ulva has a peculiar profile of fatty acids distinguished by high levels of alpha-linolenic acid and stearidonic acid, the latter being an important precursor of eicosapentaenoic acid synthesis capable of rising human tissue levels. It shows angiotensin-converting enzyme (ACE)-inhibitory activity and immunomodulatory effects.
Umibudo is called sea grapes which are sold as fresh rather than in dried form. Seagrapes are a strong source of protein, minerals (calcium, zinc, iron), dietary fibers, vitamins (A, C), saturated fatty acids, and unsaturated fatty acids. It is the staple ingredient in Okinawan cuisine with a nickname called “longevity seaweed”.Polysaccharides and oligosaccharides present in umibudo have anticoagulant, immunomodulatory and cancer-preventive effects.
Wakame is also known as sea mustard andmiyeok in Korea is a brown algae. this contains high levels of iron, phosphorous, copper, sodium, calcium, iodine, thiamine, niacin, and vitamins A, C, E, K. It is also an excellent source of eicosapentanoic acid. It is used to make salads and miso soups. Studies conducted show that a compound called fucoxanthin in wakame helps to burn fatty tissues.
In traditional Asian medicines, wakame is used for blood purification, skin, hair, regular periods, intestinal strength, and reproductive organs. Wakame has a subtly sweet taste with a satiny texture. Wakame expands during cooking so it is necessary to cut it into pieces and overcooked wakame has a slimy texture.
Benefits of Seaweeds
Traditionally, marine algae are used in both human and animal nutrition. Seaweeds are a good source of protein; the protein content depends on the seasonal periods and differs among species. Red algae are used in food additives. It is used to make agar which plays the role of a gelling and thickening agent in the food industry. Carrageenans are widely used in the food industry as a thickening, gelling, and stabilizing agents. Spirulina can be used as a dietary supplement and feed supplement (aquaculture, aquarium, and poultry industry)
Algae are used to make medicines to treat iodine deficiency, cancer, edema, urinary infection, testicular pain and swelling, and also sore throat. Researchers found that carrageenan is thought to reduce human papillomavirus (HPV).
Seaweeds are used in pharmaceutical industries due to their anti-aging, anti-inflammatory, and moisturizing property. They are an important ingredient in shampoos, lotions,anti-aging serums, creams, facial masks,and even in toothpaste.
Maerl extracts are used to create a ruminal buffer,(buffer used in ruminant feed or dairy feed to maintain the function of the rumen. Maerl is formed from dead corraline algae which are a good source of calcium carbonate. Red algae contain specific protein phycoerythrin used as a dye in biotechnology applications.Sea weed oil is produced from macroalgae, it is also called algae oil. Seaweed oil is rich in omega 3 fatty acids EPA and DHA, due to which it is used as a fatty acid dietary supplement. Seaweed oil is also used in beauty products. Algae oil is also used as biofuel.
So here are the few types of seaweeds and their benefits.
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