Khác biệt giữa bản sửa đổi của “Carrageenan”
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'''Carrageenan''' hay '''caragenan''' là nhóm các [[polysaccharid]] mạch thẳng sulfat hóa, được chiết từ các loài rong sụn , rong đỏ. Carrageenan được ứng dụng rộng rãi trong [[công nghiệp thực phẩm]] với các tính chất như tạo gel, làm dày, ổn định. Ứng dụng quan trọng của phụ gia này là trong các sản phẩm thịt và sữa, do khả năng liên kết tốt với các protein thực phẩm. Có ba loại carrageenan, khác nhau bởi mức độ [[sulfat hóa]]. Kappa-carrageenan chỉ có một nhóm sulfat trên mỗi disaccharid. Iota-carrageenan có hai nhóm sulfat trên mỗi disaccharid. Lambda carrageenan có ba nhóm sulfat trên mỗi disaccharid.
== Tính chất==
[[File:Moleculare structure of different carrageenan types.svg|thumb|310px|Cấu trúc phân tử của các dạng carrageenan]]
Carrageenan là các polysaccharid tạo bởi các chuỗi lặp lại của các đơn vị galactose và 3,6 anhydrogalactose (3,6-AG), cả dạng sulfat hóa và không sulfat hóa. Các đơn vị này tham gia các liên kết α-1,3 và β-1,4 glycosid.
Trong thương mại có ba dạng carrageenan:
* Dạng '''kappa''' tạo nên sợi gel cứng do chứa ion [[kali]]; dạng này phản ứng với các protein sữa. Chủ yếu có nguồn gốc từ ''[[Kappaphycus alvarezii]]''.<ref name="FAO Fisheries Technical Paper No.441">[http://www.fao.org/docrep/006/y4765e/y4765e00.htm#Contents], FAO Fisheries Technical Paper No. 441</ref>
* Các dạng '''iota''' tạo nên sợi gel mềm do các ion [[calci]]. Chủ yếu có nguồn gốc từ ''[[Eucheuma denticulatum]]''.<ref name="FAO Fisheries Technical Paper No.441"/>
* Dạng '''lambda''' không tạo gel, chủ yếu làm chất làm dày trong sữa. Nguồn chủ yếu là từ ''[[Gigartina]]''.
Khi sử dụng trong thực phẩm, carrageenan là phụ gia mang số hiệu E407 (hoặc E407a đối với "processed eucheuma seaweed").
<!--
Carrageenan is mainly composed of dietary fibre, which balances the nutrition better.<ref name="Marine Science Co. Ltd. Japan">http://www.marine-science.co.jp/english/goods/carra.html, Marine Science Co. Ltd.</ref> Technically Carrageenan is considered a Dietary Fibre.<ref name="Vegetarian Times April 1993">http://books.google.co.in/books?ei=YdDOUOGKPIqNrgfJ9oDABA<http://books.google.co.in/books?ei=YdDOUOGKPIqNrgfJ9oDABA&id=hQgAAAAAMBAJ&dq=vegetarian+times+april+1993&jtp=28#v=onepage&q&f=false>&id=hQgAAAAAMBAJ&dq=vegetarian+times+april+1993&jtp=28#v=onepage&q&f=false, Vegetarian Times April 1993.</ref>
In parts of Scotland and Ireland, where it is known by [[Chondrus_Crispus#Names_in_various_languages|a variety of local and native names]], ''Chondrus crispus'' is boiled in milk and strained, before sugar and other flavourings such as vanilla, cinnamon, brandy, or whisky are added. The end-product is a kind of jelly similar to pannacotta, tapioca, or blancmange.
== Production == --->
[[File:Eucheuma denticulatum in an off-bottom cultivation, Bweleo, Zanzibar.JPG|thumb|''[[Eucheuma denticulatum]]'' được trồng ở Tanzania để thu iota-carrageenan.]] <!--
Although carrageenans were introduced on an industrial scale in the 1930s, they were first used in [[China]] around 600 B.C. (where ''Gigartina'' was used) and in [[Ireland]] around 400 A.D.{{Citation needed|date=July 2009}} Carrageen gelatin can be prepared at home using the traditional recipe found in Diderot's encyclopedie and used for centuries. 5oz rinsed Irish moss is cooked with 8 quarts of water for 10 minutes, stirred as it boils. Hard water should be mixed with 1/2 oz of borax. Two quarts of cold water are rapidly added to the hot brew, and after the mixture has cooled it is strained through a cloth. It is then cooled for 24 hours and becomes gelatinous.{{Citation needed|date = April 2014}}
{{As of|2011}}, global sales of carageenan were estimated at $640 million.<ref name=":0">{{Cite report|accessdate = 6 April 2014|title = Carrageenan Industry Report 2012 Contents|date = 2012|publisher = CyberColloids Ltd.|url = http://www.cybercolloids.net/sites/default/files/private/downloads/Carrageenan%20market%20report%202012%20contents.pdf}}</ref> The largest producer of industrial carrageenan was the [[Philippines]], where cultivated seaweed produces about 80% of the world supply,<ref>{{Cite news|title = DA: Phl to regain leadership in seaweed production|date = 14 September 2011|url = http://www.philstar.com/nation/726503/da-phl-regain-leadership-seaweed-production|last = Pareño|first = Roel|publisher = [[The Philippine Star]]|accessdate = 6 April 2014}}
</ref> while China is the main exporter to global markets in the US and Europe.<ref name=":0" /> The most commonly used sources are ''E. cottonii'' (''Kappaphycus alvarezii, K.striatum'') and ''E. spinosum'' (''Eucheuma denticulatum''), which together provide about three-quarters of the world production. These grow from the sea surface to a depth of about 2 metres. The seaweed is normally grown on nylon lines strung between bamboo floats, and it is harvested after three months or so, when each plant weighs approximately 1 kg.
The ''E. cottonii'' variety has been reclassified as ''Kappaphycus cottonii'' by Maxwell Doty (1988), thereby introducing the genus ''Kappaphycus'', on the basis of the phycocolloids produced (namely kappa carrageenan).{{Citation needed|date=July 2009}}
After harvest, the seaweed is dried, baled, and sent to the carrageenan manufacturer. There the seaweed is ground, sifted to remove impurities such as [[sand]], and washed thoroughly. After treatment with hot [[alkali]] solution (e.g., 5–8% [[potassium hydroxide]]), the [[cellulose]] is removed from the carrageenan by [[centrifugation]] and [[filtration]]. The resulting carrageenan solution is then concentrated by [[evaporation]]. It is dried and ground to specification.
There are three types of industrial processing:
===Semi-refined===
This is only performed using ''E. cottonii'' or ''E. spinosum''. The raw weed is first sorted and crude contaminants are removed by hand. The weed is then washed to remove salt and sand, and then cooked in hot alkali to increase the gel strength. The cooked weed is washed, dried, and milled. ''E. spinosum'' undergoes a much milder cooking cycle, as it dissolves quite readily. The product is called semi-refined carrageenan, Philippines natural grade or, in the U.S., it simply falls under the common carrageenan specification.<ref>CyberColloids: [http://www.cybercolloids.net/library/euspecs/e-407-carrageenan E407 Specification Carrageenan], CyberColloids, Hydrocolloids research and development webpage.</ref>
cleaned and washed seaweed
↓
extraction
↓
coarse filtration → seaweed residue
↓
fine filtration → used filter aids
↓
------------ concentration --------↓
preparation with KCl preparation with alcohol
↓ ↓
gel pressing alcohol recovery
↓ |
drying |
↓ ↓
milling drying
↓ ↓
blending milling
↓ ↓
gel refined carrageenan blending
↓
refined carrageenan
===Refined===
The essential difference in the refining process is that the carrageenan is first dissolved and filtered to remove cell wall debris. The carrageenan is then precipitated from the clear solution either by isopropanol or by potassium chloride.<ref>CyberColloids: [http://www.cybercolloids.net/library/euspecs/e-407a-processed-eucheuma-seaweed E407a Specification Procesed Eucheuma Seaweed], Hydrocolloids research and development webpage.</ref>
===Mixed processing===
A hybrid technology in which seaweed is treated heterogeneously as in the semirefined process exists, but alcohol or high salt levels are used to inhibit dissolution. This process is often used on South American seaweeds and gives some of the cost benefits of semirefined processing, while allowing a wider range of seaweeds to be processed, however, the naturally low cellulose levels in some South American seaweeds allow them to be heterogeneously processed and still be sold under the EU refined specification.
== Uses ==
===Food and other domestic uses===
* [[Dessert]]s, [[ice cream]], cream, milkshakes, salad dressings, sweetened [[condensed milk]]s, and [[sauce]]s: gel to increase viscosity
* [[Beer]]: clarifier to remove haze-causing proteins
* [[Pâté]]s and processed [[meat]]s (ham, e.g.): substitute for fat, increase water retention, and increase volume, or improve sliceability
* [[Toothpaste]]: stabilizer to prevent constituents separating
* [[Fruit Gushers]]: ingredient in the encapsulated gel
* Fire fighting foam: thickener to cause foam to become sticky
* [[Shampoo]] and cosmetic creams: thickener
* Air freshener gels
* [[Paper marbling|Marbling]]: the ancient art of paper and fabric marbling uses a carrageenan mixture on which to float paints or inks; the paper or fabric is then laid on it, absorbing the colours
* Shoe polish: gel to increase [[viscosity]]
* [[Biotechnology]]: gel to immobilize cells/enzymes
* Pharmaceuticals: used as an inactive [[excipient]] in pills/tablets
* [[Soy milk]] and other [[plant milk]]s: used to thicken, in an attempt to emulate the consistency of whole milk
* [[Diet soda]]s: to enhance texture and suspend flavours
* [[Pet food]]
* [[Personal lubricant]]s
* [[Vegetarian hot dog]]s
===Medical uses=== --><!-- This section is linked from [[Human papillomavirus]] --><!--
[[File:Divine-9-carrageenan.JPG|thumb|right|200px|Personal lubricant made from carrageenan]]
A 2006 ''in vitro'' study and a 2007 mouse study at the [[National Cancer Institute]] in the United States suggested that carrageenans might function as a [[Microbicides for sexually transmitted diseases|topical microbicide]].<ref name="Buck 2006">{{cite journal|last1=Buck|first1=Christopher B.|last2=Thompson|first2=Cynthia D.|last3=Roberts|first3=Jeffrey N.|last4=Müller|first4=Martin|last5=Lowy|first5=Douglas R.|last6=Schiller|first6=John T.|date=July 2006|title=Carrageenan is a potent inhibitor of papillomavirus infection|journal=PLoS Pathogens|volume=2|issue=7|pages=671–680|doi=10.1371/journal.ppat.0020069|pmid=16839203|pmc=1500806|quote=Some, but not all, carrageenan-containing over-the-counter sexual lubricant gels we tested were extremely effective for blocking the infectivity of an HPV16 reporter pseudovirus in vitro. These results raise the possibility that use of such lubricant products, or condoms lubricated with carrageenan based gels, could block the sexual transmission of HPV. However, in the absence of clinical efficacy data, it would be inappropriate to recommend currently available products for use as topical microbicides.}}</ref><ref name="Roberts 2007">{{cite journal|last1=Roberts|first1=Jeffrey N.|last2=Buck|first2=Christopher B.|last3=Thompson|first3=Cynthia D.|last4=Kines|first4=Rhonda|last5=Bernardo|first5=Marcelino|last6=Choyke|first6=Peter L.|last7=Lowy|first7=Douglas R.|last8=Schiller|first8=John T.|date=July 2007|title=Genital transmission of HPV in a mouse model is potentiated by nonoxynol-9 and inhibited by carrageenan|journal=Nature Medicine|volume=13|issue=7|pages=857–861|doi=10.1038/nm1598|pmid=17603495}}</ref> A 1987 ''in vitro'' study in Spain revealed a broad spectrum antiviral activity of carrageenan.<ref name="González 1987">{{cite journal|last1=González|first1=María Eugenia|last2=Alarcón|first2=Balbino|last3=Carrasco|first3=Luis|date=September 1987|title=Polysaccharides as antiviral agents: antiviral activity of carrageenan|journal=Antimicrobial Agents and Chemotherapy|volume=31|issue=9|pages=1388–1393|doi=10.1128/AAC.31.9.1388|pmid=2823697|pmc=174948}}</ref>
====HSV====
There are indications a carrageenan-based gel may offer some protection against [[Herpes simplex virus 2|HSV-2]] transmission by binding to the receptors on the herpes virus, thus preventing the virus from binding to cells. Research has shown a carrageenan-based gel effectively prevented HSV-2 infection at a rate of 85% in a mouse model.<ref name="Population Council 2009">{{cite web|author=Population Council|title=Microbicides program|date=August 17, 2009|location=New York|publisher=Population Council|url=http://www.popcouncil.org/microbicides/index.html|archivedate=November 3, 2009|archiveurl=http://web.archive.org/web/20091103113443/http://www.popcouncil.org/microbicides/index.html|accessdate=September 5, 2007}}</ref>
====HPV====
Laboratory studies have shown carrageenans inhibit [[HPV]] infection ''in vitro'' and in mouse challenge models.<ref name="Buck 2006"/><ref name="Roberts 2007"/>
A substudy of a South African HIV-prevention clinical trial found a lower prevalence of high risk HPV infection in users of a carrageenan-based vaginal microbicide, ''Carraguard'', versus placebo users at the end of the trial—prevalence of high risk HPV infection at the beginning of the trial was not ascertained.<ref name="Marais 2010">{{cite web|last1=Marais|first1=Dianne|last2=Gawarecki|first2=Daniel|last3=Rutenberg|first3=Naomi|last4=Allan|first4=Bruce|last5=Ahmed|first5=Khatija|last6=Altini|first6=Lydia|last7=Cassim|first7=Nazira|last8=Gopolang|first8=Felicity|last9=Hoffman|first9=Margaret|last10=Williamson|first10=Anna-Lise|date=July 2010|title=P-107: Carraguard, a vaginal microbicide, protects women against HPV infection (poster)|location=Montreal, Canada|publisher=26th International Papillomavirus Conference, July 3–8, 2010|url=http://www.hpvmedia.org/index.php?option=com_hpv&view=presentation&id=1110|archiveurl=http://web.archive.org/web/20110726155237/http://www.hpvmedia.org/index.php?option=com_hpv&view=presentation&id=1110|archivedate=July 26, 2011|accessdate=July 20, 2010}}</ref><ref name="Marais 2011">{{cite journal|last1=Marais|first1=Dianne|last2=Gawarecki|first2=Daniel|last3=Allan|first3=Bruce|last4=Ahmed|first4=Khatija|last5=Altini|first5=Lydia|last6=Cassim|first6=Nazira|last7=Gopolang|first7=Felicity|last8=Hoffman|first8=Margaret|last9=Ramjee|first9=Gita|last10=Williamson|first10=Anna-Lise|year=2011|title=The effectiveness of Carraguard, a vaginal microbicide, in protecting women against high-risk human papillomavirus infection|journal=Antiviral Therapy|volume=16|issue=8|pages=1219–1226|doi=10.3851/IMP1890|pmid=22155903|url=http://www.intmedpress.com/serveFile.cfm?sUID=f9170522-1145-4fd4-94fe-99099cc9d23d}}</ref>
====HIV====
A phase 3 [[clinical trial]] by the [[Population Council]] examined whether a carrageenan-based product was effective as a [[topical microbicide]] for blocking [[HIV]] infection in women.<ref name="Population Council 2009"/> The trial ran from 2004 to 2007, with more than 4,000 [[South Africa]]n women completing the study, but found no statistical difference in infection between those having used the lubricant and those not having used the lubricant.<ref>{{cite web
| title = Trial Shows Anti-HIV Microbicide Is Safe, but does Not Prove it Effective
| work = Population Council
| accessdate = 2008-03-12
| date = 18 February 2008
| url = http://www.popcouncil.org/mediacenter/newsreleases/Carraguard_Findings.html
}}</ref><ref>
{{cite web
| title = Experimental Microbicide Carraguard Does Not Provide Protection Against HIV, Study Finds
| work = kaisernetwork.org
| accessdate = 2008-03-12
| date = 20 February 2008
| url = http://www.kaisernetwork.org/Daily_reports/rep_index.cfm?DR_ID=50494
}}</ref> The trial also provided information about usage patterns and showed that the gel does not increase infection any more than the baseline or cause significant side-effects. As such, it is expected to be used as a stable delivery vehicle for experimental [[antiretroviral]]s in future studies.
Concurrent studies in macaques found the same carrageenan gels used in clinical trials to be effective against [[Simian immunodeficiency virus|SIV]] challenge. This was in direct contrast with ''in vitro'' findings, where the compound was found to enhance HIV and SIV infections in various assays. Although compliance was believed to be one issue in clinical versus animal trials, the high viscosity and controlled nature of animal-viral inoculations (atraumatic introduction of virus using a French [[catheter]]) may be why the latter animal study observed a positive outcome.<ref name=r6/>
====Common cold====
Clinical studies have shown coating the insides of the nose with carrageenans to be preventative against [[common cold]] [[virus]] infections.<ref name=r5/>
====Animal models====
Dilute lambda carrageenan solution (1–2%) injected subcutaneously causes swelling and pain. It is used in animal models of [[inflammation|inflammatory pain]] e.g. to test efficacy of [[analgesics]].
==Health concerns==
===Cancer and gastrointestinal effects===
There have been several peer-reviewed animal studies suggesting tumor promotion or initiation by carrageenan.<ref>Watanabe, K., Reddy, B. S., Wong, C. Q., & Weisburger, J. H. (1978). [http://cancerres.aacrjournals.org/content/38/12/4427.full.pdf Effect of dietary undegraded carrageenan on colon carcinogenesis in F344 rats treated with azoxymethane or methylnitrosourea]" ''Cancer Research'' 38(12), 4427-4430.</ref><ref>Taché, S, Peiffer, G, Millet, A-S, and Corpet, DE. Carrageenan gel and aberrant crypt foci in the colon of conventional and human flora-associated rats. Nutr Cancer 37:75–80, 2000.</ref><ref>Yasuyuki Oohashi, Tomonori Ishioka, Kazuo Wakabayashi, Noriyuki Kuwabara. (1981). A study on carcinogenesis induced by degraded carrageenan arising from squamous metaplasia of the rat colorectum. Cancer Letters, 14(3):267-272.</ref><ref>Corpet, DE, Taché, S, and Préclaire, M. Carrageenan given as a jelly, does not initiate, but promotes the growth of aberrant crypt foci in the rat colon" ''Cancer Lett'' 114:53–55, 1997b.</ref> In an industry-funded study, Cohen & Ito discuss methodological problems with four such studies, along with several evaluations of genotoxic activity, and conclude that there is no credible evidence that carrageenan contributes to tumor promotion or colon cancer.<ref>Cohen S and Ito N (2002) A critical review of the toxicological effects of carrageenan and processed eucheuma seaweed on the gastrointestinal tract.[[Crit Rev in Toxicol]] 32(5) 413-444</ref> In contrast, Tobacman's review of 45 publicly funded studies concludes that "the potential role of carrageenan in the development of gastrointestinal malignancy and inflammatory bowel disease requires careful reconsideration of the advisability of its continued use as a food additive."<ref name="Tobacman2001"/> As of 2011, Kanneganti et al. note that "the role of both CGN [carrageenan] and dCGN [degraded carrageenan] as carcinogens still remains controversial".<ref>Kanneganti, M., Mino-Kenudson, M., & Mizoguchi, E. (2011). Animal models of colitis-associated carcinogenesis. BioMed Research International, 2011.</ref>
Studies conducted with isolated cells and human intestinal epithelial cells in tissue culture as models for in vivo conditions have suggested carrageenan may trigger a number of responses in the body that lead to inflammation of the intestines or, bind to and activate several membrane receptor signaling pathways.<ref>Bhattacharyya S, Dudeja PK and Tobacman JK (2010) Tumor necrosis factor alpha-induced inflammation is increased but apoptosis is inhibited by common food additive carrageenan.[[Journal of Biological Chemistry]] 285(50): 39511-22</ref><ref>Borthakur A, Bhattacharyya S, Anbazhagan AN, Kumar A, Dudeja PK and Tobacman JK (2012) Prolongation of carrageenan-induced inflammation in human colonic epithelial cells by activation of an NFκB-BCL10 loop. Biochimica and Biophysica Acta 1822(8): 1300-7</ref>
Carrageenan is commonly used to induce inflammatory responses in mice. Notably, the air pouch inflammation model is based on administration of 1% carrageenan into sub-cutaneous air pouches in mice and strong inflammatory reactions are observed as early as 4 hours post administration. This in vivo inflammation model has been widely used to study the effect of anti-inflammatory compounds.<ref>Duarte DB, Vasko MR, Fehrenbacher JC. (2012) Models of Inflammation: carrageenan air pouch. Current Protocols in Pharmacology, Chapter 5</ref>
Carrageenan's function as a food additive relates to its large molecular weight (200,000 - 800,000 Da) and tight binding to food protein, but also influences carrageenan's fate as it passes through the GI tract. Oral feeding studies with laboratory animals indicate dietary carrageenan is excreted quantitatively <ref>Uno Y, Omoto T, Goto Y, et al., (2001) Molecular weight and fecal excreted quantity of carrageenan administered to rats in blended feed. [[Japanese Journal of Food Chemistry]] 45(1):98-106</ref><ref>Weiner ML (1988) Intestinal transport of some macromolecules in food. [[Fd Chem Toxicol]] 26:867-880</ref> and is not accumulated in body organs such as the liver or colon;<ref>Pittman KA, Golberg L, Coulston F (1976) Carrageenan: the effect of molecular weight and polymer type on its uptake, excretion and degradation in animals. [[Fd Cosmet Toxicol]] 14:85-93</ref> studies disagree with respect to whether it triggers gastrointestinal tract inflammation or contributes to tumor promotion.<ref name="Tobacman2001"/><ref>Weiner ML, Nuber D, Blakemore WR et al., (2007) A 90-day dietary study of kappa carrageenan with emphasis on the gastrointestinal tract.[[Fd Chem Toxicol]] 45:98-106</ref> Long-term oral feeding studies found no adverse effects on male or female infant baboons reared from birth to 112 days of age on infant formula containing carrageenan at 5-times the concentration typically present in human infant formula as their only diet,<ref>McGill HC,Jr., McMahan CA, Wigodsky HS, Sprinz H. (1977) Carrageenan in formula and infant baboon development. [[Gastroenterology]] 73:512-517</ref> but did observe histopathologic changes in rhesus monkey colon after drinking solution containing 1% undegraded carrageenan.<ref>Mankes & Abraham, 1975, as cited in Tobacman, J.K. (2001), [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242073/pdf/ehp0109-000983.pdf Review of harmful gastrointestinal effects of carrageenan in animal experiments].[[Environ Health Perspect]] 109(10):983-984.</ref> Similarly, while no adverse effects were observed for multi-generations of rats fed up to 5% dietary carrageenan,<ref>Collins TFX, Black TN, Prew JH (1977a) Long-term effects of calcium carrageenan in rats. 1. Effects on reproduction. [[Fd Cosmet Toxicol]] 15:533-538</ref><ref>Collins TFX, Black TN, Prew JH (1977b) Long-term effects of calcium carrageenan in rats. II. Effects on fetal development. [[Fd Cosmet Toxicol]] 15:539-545</ref> or on hamsters and rats fed for a lifetime diets containing up to 5% carrageenan,<ref>Rustia M, Shubik P, Patil K (1980) Lifespan carcinogenicity test with native carrageenan in rats and hamsters. [[Cancer Letters]] 11(1):1-10</ref><ref>Abraham R, Benitz KF, Mankes R, Rosenblum I (1985) Chronic and subchronic effects of various forms of carrageenan in rats [[Ecotoxicology and Environmental Safety]] 10:173-183</ref> administration of carrageenan to rodents in drinking water has resulted in some observations of GI-tract effects.<ref>Wilcox DK, Higgins J and Bertram TA (1992) Colonic epithelial cell proliferation in a rat model of nongenotoxin-induced colonic neoplasia [[Lab Invest]] 67(3):405-411</ref><ref>Calvert RJ and Satchithanandam S (1992) Effects of graded levels of high-molecular-weight carrageenan on colonic mucosal thymidine kinase activity [[Nutrition]] 8(4):252-257</ref><ref>Calvert RJ and Reicks M (1988) Alterations in colonic thymidine kinase enzyme activity induced by consumption of various dietary fibers [[Proc Soc Exp Biol Med]] 189(1)45-51</ref> Tight binding of carrageenan to ingested food proteins is considered less available than in drinking water for interaction with the absorptive cells of the GI tract, although some studies have linked food-grade carrageenan to gastrointestinal disease in laboratory animals, including ulcerative colitis-like disease, intestinal lesions, and ulcerations.<ref>Watt J and Marcus R (1969) Ulcerative colitis in the guinea-pig caused by seaweed extract. Journal of Pharmacy and Pharmacology 21:187S–188S</ref><ref>Grasso P, Sharratt M, Carpanini FMB, Gangolli SD (1973) Studies on carrageenan and large-bowel ulceration in mammals. [[Food and Cosmetics Toxicology]] 11:555–564</ref><ref>Engster M and Abraham R (1976) Cecal response to different molecular weights and types of carrageenan in the guinea pig. [[Toxicology and Applied Pharmacology]] 38:265–282</ref><ref>Watanabe K, Reddy BS, Wong CQ, Weisburger JH (1978) Effect of dietary undegraded carrageenan on colon carcinogenesis in F344 rats treated with azoxymethane or methylnitrosourea. Cancer Research 38:4427–4430</ref><ref>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242073/pdf/ehp0109-000983.pdf Review of harmful gastrointestinal effects of carrageenan in animal experiments] J. K. Tobacman (2001)</ref>
Carrageenan is inert to hydrolysis by intestinal enzymes in both humans and monogastric animals.<ref>Harmuth-Hoene AE and Schwerdtfeger E (1979) Effects of indigestible polysaccharides on protein digestibility and nitrogen retention in growing rats. [[Nutr Metab]] 23:399-407</ref><ref>Cummings JH, Jenkins DJA and Wiggins HS (1976) Measurement of the mean transit time of dietary residue through the human gut. [[Gut]]17:216-218</ref> Many older studies and a few recent studies have been based on the use of "degraded carrageenan," a fraction of low-molecular weight segments of the carrageenan molecular backbone called "poligeenan." To resolve this within the scientific community, the U.S. Adopted Names Council assigned the name "poligeenan" to the fragments with molecular weight of 10,000 to 20,000 Da.<ref>United States Adopted Names Council (1988)</ref><ref>CAS Number 53973-98-1</ref> Approximately 8% of the fragments of food-grade carrageenan are of molecular mass less than 50,000 Da, in excess of the recommended minimum of 5% set by the European Scientific Committee on Food to ensure that the presence of poligeenan is kept to a minimum.<ref name="Spichtig2008"/> The proportion of this 8% that consists of poligeenan is unknown.
===Regulatory status===
In the U.S., carrageenan is allowed under FDA regulations<ref>21 Code of Federal Regulations 172.620</ref> as a direct food additive and is considered safe<ref>Generally Recognized As Safe [[21 CRF §182.7255]] GRAS ID Code 9000-07-1 (1973)</ref> when used in the amount necessary as an emulsifier, stabilizer, or thickener in foods, except those standardized foods that do not provide for such use. FDA also reviewed carrageenan safety for infant formula.<ref>Federal Food, Drug, and Cosmetic Act [[21 U.S.C. 350(a)]] §412</ref> The National Organic Program (NOP) added carrageenan to the National List;<ref>68 FR 61993 (2003)</ref> reviewed and reauthorized in 2008<ref>65 FR 80548</ref> as "critical to organic production and handling operations".<ref>73 FR 59481</ref> The European Food Safety Authority concluded "there is no evidence of any adverse effects in humans from exposure to food-grade carrageenan, or that exposure to degraded carrageenan from use of food-grade carrageenan is occurring",<ref>Opinion of the Scientific Committee on Food on Carrageenan (2003) [http://ec.europa.eu/food/fs/sc/scf/out164_en.pdf] p. 5</ref> however, the Joint [[FAO]]/[[WHO]] expert committee on food additives states that "based on the information available, it is inadvisable to use carrageenan or processed eucheuma seaweed in infant formulas".<ref>[http://web.archive.org/web/20080314152241/http://www.who.int/ipcs/food/jecfa/summaries/summary68.pdf Joint FAO/WHO Expert Committee on Food Additives]. Who.int. Retrieved on 2011-12-10.</ref>
===Effects of radiation===
Environmental advocate Dr. [[Helen Caldicott]] has drawn attention to the effect of [[radiation effects from the Fukushima Daiichi nuclear disaster]] on ocean life, arguing that seaweeds come from the Pacific Ocean must be looked at carefully.<ref>Caldicott, Helen. "The Medical Implications of Fukushima". Invited talk. International House of Japan in Roppongi, Tokyo, on July 7, 2013.</ref> Concerns include the potential presence of carcinogenic radionuclides and the degradation of carrageenan by radiation; radiation degrades carrageenan,<ref>L. Rellevea, N. Nagasawab, L.Q. Luanc, T. Yagib, C. Aranillaa, L. Abada, T. Kumeb, F. Yoshiib, A. dela Rosaa (2005) Degradation of carrageenan by radiation. [[Polymer Degradation and Stability]] 87(3):403-410</ref> and degraded carrageenan has been more closely associated with adverse health outcomes than undegraded carrageenan in animal studies.<ref name="Tobacman2001"/> No studies have yet been conducted to determine whether radiation-exposed Pacific seaweeds pose a danger to human health.
== Grades ==
{{See also|Food grading}}
{{unreferenced section|date=March 2013}}
There are two basic grades of carrageenan: refined carrageenan (RC) and semi refined carrageenan (SRC). In the United States, RC and SRC are both labeled as carrageenan. In the European Union, RC is designated by the [[E number]] E-407, and SRC is E-407a. RC has a 2% maximum for acid insoluble material and is produced through an alcohol precipitation process or potassium chloride gel press process. SRC contains a much higher level of cellulosic content and is produced in a less complex process. Indonesia, The Philippines, and Chile are three main sources of raw material and extracted carrageenan.
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== Xem thêm ==
{{Wiktionary|carrageenan}}
* [[Agar]]
* [[Danh mục phụ gia thực phẩm]]
== Chú thích==
{{Reflist}}
[[Category:Polysaccharid]]
[[Category:Phụ gia thực phẩm]]
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