Fish Products and Byproducts Technology

Unit 12 - Seaweeds

12.5. Utilization of seaweeds
Seaweeds are important component of the marine living resources. Seaweeds are mostly found in shallow coastal water area and rocky shores. Seaweeds are broadly grouped into green, brown, red and blue-green algae based on their pigmentation. Seaweeds are mostly harvested in Japan and China and are used as medicine, food, fodder and manure. Maritime countries used seaweeds as vermifuge, anesthetic and ointment as well as for the treatment of cough, wounds, gout, goiter, etc. Sailors have been treating wounds for last several years with seaweeds. Sterols and related compounds present in seaweeds have ability to lower blood plasma cholesterol level. Seaweeds dietary fiber perform varied range of function such as anti-oxidant, anti-mutagenic, anticoagulant, anti-tumor etc. High intake of calcium, potassium and sodium are associated with lower mean systolic pressure and lower risk of hypertension. Seaweeds contain high amount of potassium, which is identical with our natural plasma level. The research work in this type shown that seaweed extract is similar to human blood plasma.
In India, seaweed is used as manure especially for coconut plantations in Tamil-Nadu. Plants readily absorb the high amount of water-soluble potash and other minerals present in seaweeds. The carbohydrate and other chemicals present in the seaweeds improve the moisture retaining capacity of the soil and control certain plant diseases. So all kind of seaweed and sea-grasses can be used as manure either directly or in the form of compost.
Varieties of food items are prepared in Japan from seaweeds. The seaweed are being used as salad, boiled (Kelp), jelly (red seaweed), vinegar dish (brown and red seaweed) and spices (red green and brown seaweed). The most common use of Porphyra (Nori) is as ingredient in dishes like "Sushi" wherein the seaweed sheets are wrapped around flavored rice. Dried Laminaria serve as soup or eaten as a vegetable and large quantity consumed in Japan and China where it is called "Kombu". In India, people belonging to coastal belt of Tamil Nadu consume Gracilaria lichenoides as food in the preparation of porridge or "Kanji". Presence of all the amino acids in the protein needed in the human diets have been observed in the Indian seaweeds. Green seaweed and red seaweed contain 2-2.5 % of protein. The vitamins namely A, B and B12 are found higher in many algae as compared to much other food material.
In India, seaweeds are used to certain extent as food in coastal areas of Tamil Nadu where Gracilaria edulis is being used since decades for making gruel. Some common products prepared from seaweeds are, agar-agar, algin, seaweed meal, Ulva jam, seaweed salad, seaweed vegetable, seaweed curry, seaweed porridge, seaweed manure, seaweed compost, seaweed meal for poultry and cattle and some medicinal products.