Seaweed or marine algae belong to a large group of autotrophic organisms. They can be unicellular (microalgae or phytoplankton) or multicellular (macroalgae) with sizes ranging from 0.2-2.0 microns up to 60 m, respectively. Their reproduction occurs through simple division and due to the simplicity of their structure, they tend to grow faster than any other plant. Therefore, they are characterized as the most productive plants on the planet (
Marsall, 2007):
- Compared to traditional oilseeds, algae can produce five times more biomass per hectare.
There are about 320,500 species of algae.The amount of cultivated or native macroalgae used in industry during recent years rounds up to nearly 7.5-8 million tons per year (
Becker, 2007).
Nutritional composition of algae
The nutritional value of algae depends on their size, digestibility, presence of toxic substances and chemical composition (
Becker, 1994).
Algae are a
remarkable source of protein, with a content of 10-15% in macro-algae (
Oliveira et al., 2009) and 28-71% in microalgae. In addition, the content of certain amino acids such as lysine, methionine, tryptophan, threonine, valine, histidine and isoleucine is
comparable to that of eggs or soybean seeds. [register]
- Protein digestibility may vary depending on: algae species, time of year and the presence of phenols or polysaccharides, as well as the animal species to which they are administered (Goni et al., 2002).
Fleurence (1999) observed that the protein content in algae was highest at the end of the winter months and lowest during the summer months.
Fat content in seaweed ranges from 1-40% (
Borowitzka, 1988),and fatty acids can be saturated or unsaturated.
Particularly,
spirulina algae contain 20-30% linolenic acid, while
Porphrìdium cruentum known as red algae, is
one of the richest sources of arachidonic acid. Containing close to 36% of total fats at 25°C, while at 16°C it increases to 60%.
- Many species of algae can produce oils that are similar in structure to those of vegetables. For example those obtained from soybeans.
Different species of algae are very good sources of cellulose, with contents of up to 35-50 g/100 g in dry matter (
Lahaye, 1991).
Their
mineral content is sufficiently high (13-25%) compared to other plant organisms (5-10% – USDA 2001). Their contents of both macronutrients (Na, K, Ca, Mg) and trace elements (Fe, Zn, Mn, Cu) are high. Ranging from 8-17g/100g of algae and 5.1-15.2 mg/100g of algae, respectively.
- In addition, algae contain remarkable amounts of iodine (0.1-1.1%).
Moreover, the various species of algae(seaweed) make up a valuable source of almost all important vitamins, such as tocopherols, ascorbic acid, B1; B2, B6, B12, nicotinic acid, provitamin A, etc.
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