Chlorella: Perbedaan antara revisi
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{{Taxobox |
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| color = lightgreen |
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| name = Chlorella |
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| regnum = [[Plant]]ae |
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| divisio = [[Chlorophyta]] |
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| classis = [[Chlorophyceae]] |
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| ordo = [[chlorococcales]] |
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| familia = [[Oocystaceae]] |
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| genus = '''''Chlorella''''' |
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| subdivision_ranks = Spesies |
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| subdivision = * ''Chlorella vulgaris pyrenoidosa'' |
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* [[Chlorella pyrenoidosa]] |
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}} |
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'''Chlorella''' is a [[genus]] of single-[[Cell (biology)|celled]] green [[algae]], belonging to the phylum [[Chlorophyta]]. It is spherical in shape, about 2 to 10 [[Metre#SI prefixes applied to the metre|μm]] in diameter, and is without [[flagella]]. ''Chlorella'' contains the green photosynthetic pigments [[chlorophyll]]-a and -b in its [[chloroplast]]. Through [[photosynthesis]] it multiplies rapidly requiring only [[carbon dioxide]], [[water]], [[sunlight]], and a small amount of [[mineral]]s to reproduce. |
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The name ''Chlorella'' is taken from the [[Greek language|Greek]] word ''chloros'' meaning green and the [[Latin]] diminutive suffix ''ella'' meaning "small". The [[Germany|German]] [[biochemist]] [[Otto Heinrich Warburg]] received the [[Nobel Prize in Physiology or Medicine]] in 1931 for his study on photosynthesis in ''Chlorella''. In [[1961]] [[Melvin Calvin]] of the [[University of California]] received the [[Nobel Prize in Chemistry]] for his research on the pathways of carbon dioxide assimilation in [[plant]]s using ''Chlorella''. In recent years researchers have made less use of ''Chlorella'' as an [[Model organism|experimental organism]] because it lacks a [[Biological life cycle|sexual cycle]] and, therefore, the research advantages of [[genetics]] are unavailable. |
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Many people believed that ''Chlorella'' could serve as a potential source of food and energy because its [[photosynthetic efficiency]] can theoretically reach 8%,<ref>I.Zelitch, Photosynthesis, Photorespiration and Plant Productivity, Academic Press, 1971, p.275</ref> this is comparable with other highly efficient crops such as sugar cane. It is also an attractive food source because it is high in [[protein]] and other essential nutrients; when dried, it is about 45% [[protein]], 20% [[fat]], 20% [[carbohydrate]], 5% fiber, and 10% minerals and [[vitamin]]s. However, because it is a single-celled algae, harvest posed practical difficulties for its large-scale use as a food source. Mass production methods are now being used to cultivate it in large artificial circular ponds. |
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==Aquarium== |
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''Chlorella'' green [[algae]] can create green and opaque water problems in [[aquarium]]s. ''Chlorella'' can grow due to high [[nitrate]] and [[phosphate]] levels or direct sunlight. Decreasing phosphate and nitrate by partial water change and moving the aquarium to shade can help in solving the problem. |
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==''Chlorella'' as a food source== |
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During the late 1940s and the early 1950s chlorella was seen as a new and promising primary food source and as a possible solution to the then current world hunger crisis. Many people during this era thought that world hunger was a growing problem and saw chlorella as a way to end this crisis by being able to provide large amounts of high quality food for a relatively low cost.<ref>Belasco, Warren. "Algae Burgers for a Hungrey World? The Rise and Fall of Chlorella Cuisine"</ref> |
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Following global fears of an uncontrollable population boom in the 1940's, chlorella became a possible answer to the tremendous food shortages the world would face in light of this speedy, post-war growth. Many institutions stepped up to research the algae, including the Carnegie Institution, the Rockefeller Foundation, the NIH, UC Berkeley, the Atomic Energy Commission, and Stanford University. Following WWI, many Europeans were starving and many Malthusians attributed this not only to the war but to the inability of the world to produce enough food to support the currently increasing population. According to a 1946 FAO report, the world would need to produce 25 to 35 percent more food in 1960 than in 1939 to keep up with the increasing population, while health improvements would require a 90 to 100 percent increase (Belasco, 612). Because meat was costly and energy intensive to produce, protein shortages were also an issue. Increasing harvest area alone would only go so far in providing adequate nutrition to the population. The USDA calculated that to feed the US population by 1975, it would have to add 200 million acres (800,000 km²) of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested solely on new agricultural techniques and technologies. Because of these circumstances, an alternative solution was needed. |
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To cope with the upcoming post-war population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the Stanford Research Institute showed that chlorella (when growing in warm, sunny, shallow conditions) could convert 20 percent of solar energy into a plant that, when dried, contained 50 percent protein (Belasco 617). In addition, chlorella contained amino acids, fat, calories and vitamins. The plant's photosynthetic efficiency allowed it to yield more protein per unit area than any other plant - one scientist predicted that 10,000 tons of protein a year could be produced with just 20 workers staffing a one thousand-acre (4 km²) chlorella farm (Belasco, 618). The pilot research performed at Stanford and elsewhere led to immense press from journalists and newspapers, yet sadly never panned out. Chlorella was a seemingly viable option because of the technological advances in agriculture at the time and the widespread acclaim it got from experts and scientists who studied it. Algae researchers had even hoped to add a neutralized chlorella powder to conventional food products, as a way to fortify them with vitamins and minerals (Belasco, 625). Unfortunately, the hype far surpassed the productivity of the plant and early estimates of its success were proven to be no more than exaggerated optimism. |
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Ultimately, scientists discovered that chlorella would be much more difficult to produce than previously thought. The experimental research was carried out in laboratories, not in the field. Practically, the entire batch of algae grown would have to be placed either in artificial light or in the shade so that it would produce at its maximum photosynthetic efficiency. Additionally, for the chlorella to be as productive as the world would require, the chlorella would have to be grown in carbonated water which would have added millions to the production cost. A sophisticated process that would cost additional money was required to harvest the chlorella, and for the chlorella to be a viable food source, its cellulose cell walls would have to be pulverized. The plant could only reach its nutritional potential in highly modified artificial situations. Economic problems and the public's distaste for the flavor of chlorella and its byproducts ultimately led to the demise of chlorella. |
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Since the growing world food problem of the 1940's was solved by better crop efficiency and not from a "super food," chlorella has lost public and scientific interest for the time being. Chlorella can still be found today in rare occasions from companies still promoting chlorella's "super food" effects.<ref>Belasco, "Algae Burgers for a Hungry World?", pp ??</ref> |
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==Nutrition== |
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It was believed in the early 1940s that unlike most plants, Chlorella’s protein was “complete,” for it had the ten amino acids then considered essential, and it was also packed with calories, fat, and vitamins(Belasco 613). |
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Chlorella has been found to have anti tumor properties when fed to mice.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=2229925&query_hl=4&itool=pubmed_docsum][http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=3253484&query_hl=4&itool=pubmed_docsum][http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=3845850&query_hl=4&itool=pubmed_DocSum] |
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Another study found enhanced vascular function in hypertensive rats given oral doses of chlorella.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17330510&query_hl=1&itool=pubmed_docsum] |
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Although at its onset Chlorella was thought by many to add a "dirt cheap" form of high protein to the human diet, studies proved otherwise. Chlorella, which actually lost most of its nutritional value when altered/processed in any way, was no longer an effective protein and therefore pro-Chlorella supporters decided to communicate other health benefits of the algae. Hence, weight control, cancer prevention, and immune system support were all positive health benefits attributed to this algae (Belasco 608,628-630). |
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It was also thought that humans would never eat algae directly; instead they believed it could be added to animal feed, thereby increasing to protein consumption indirectly (Belasco 625). |
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==Evidence of health and healing effects== |
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The marketing of ''Chlorella'' for human consumption as a palliative, or "Superfood", has received criticism{{ref_label | becker | 1 | a}} ; as such, the following recommendations should be treated as speculative: [This claim is not supported by the Zelitch reference. Find new reference or modify this section accordingly] |
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Maintenance Dosage: 3-5 grams/day |
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Significant Part of the Diet: 6-10 grams/day |
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Immune System Builder: 11-14 grams/day |
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Primary Source of Protein: 12-19 grams/day |
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Healing Purposes & Heavy Metal Detoxification: 20-30 grams/day |
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==Early Reception and Scientific Backing== |
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When the preliminary laboratory results were published the reaction of scientific literature backed the possibilities of the supposed superfood. Science News Letter praised the optimistic results in an article entitled "Algae to Feed the Starving." John Burlew, the reported editor of Carnegie Institute stated that "the algae culture may fill a very real need," which Science News Letter turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds." The cover of the magazine also featured Arthur D Little's Cambridge laboratory which was a supposed future food factory. A few years later, the magazine published an article entitled "Tomorrow's Dinner," which stated that "There is no doubt in the mind of scientists that the farms of the future will actually be factories." Science Digest also reported that "common pond scum would soon become the world's most important agricultural crop." Yet the optimistic initial promises of the algae fell short when further testing was conducted. |
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==Failures== |
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Although technologically creative and promising, Chlorella would not prove to be economically viable in the market. Experiencing competition to the health world’s soybean and whole grain craze, algae products simply could not measure up. Economically too, in practice, algae was not as cheaply or easily harvested as technicians predicted it would be 40 years earlier. The efficiency of other "normal" dietary products actually turned out to supersede that of algae growth and production. Aside from production inefficiencies, Chlorella, as it turned out, did not capture the benefits of photosynthesis and sunlight as predicted. After a decade of experimentation, and after exposed to sunlight, Chlorella captured just 2.5 percent — not much better than conventional crops (Belasco, 627). Chlorella, too, was found by scientists in the 1960s to be impossible for humans and animals to digest in its natural state, which presented further problems for the use of algae in American food production.<ref>Belasco, "Algae Burgers for a Hungry World?", pp 13-14</ref> --> |
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== Rujukan == |
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<references/> |
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Belasco, Warren. "Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine". ''Technology and Culture'', Vol. 38 No. 3, hlm 608-634 |
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==Pranala luar == |
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* Pandangan FDA (Food and Drug Administration pemerintah AS[http://www.fda.gov/cder/warn/cyber/2005/CL134e.pdf]tre |
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*[http://www.chlorellafactor.com/ Chlorella dan Spirulina - Supermakanan untuk kesehatan] |
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{{rintisan}} |
{{rintisan}} |
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[[Kategori:Ganggang hijau]] |
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[[bg:Хлорела]] |
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[[de:Chlorella]] |
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[[en:Chlorella]] |
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[[ja:クロレラ]] |
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[[pl:Chlorella]] |
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[[pt:Chlorella]] |
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[[fi:Klorella]] |
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[[uk:Хлорела]] |
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Revisi per 24 Mei 2007 02.54
| Chlorella | |
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| Klasifikasi ilmiah | |
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| Genus: | Chlorella
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| Spesies | |
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Chlorella adalah genus ganggang hijau bersel tunggal yang hidup di air tawar, laut, dan tempat basah. Ganggang ini sering digunakan di laboratorium untuk penyelidikan fotosintesis.
Rujukan
Belasco, Warren. "Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine". Technology and Culture, Vol. 38 No. 3, hlm 608-634
Pranala luar
- Pandangan FDA (Food and Drug Administration pemerintah AS[1]tre
- Chlorella dan Spirulina - Supermakanan untuk kesehatan
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