Carrageenan
Carrageenan (English carrageenan ) is the collective name of a group of long-chain carbohydrates , which in Rotalgenzellen occur.
They are linear, anionic hydrocolloids that can be distinguished by their chemical structure and have different properties. These different types differ in the proportion of galactose and 3,6-anhydrogalactose as well as in the number of sulfate groups . Κ-, ι- and λ-carrageenan are of commercial importance.
Manufacturing
To make carrageenan from red algae , the algae are washed and boiled in an alkaline solution . This process can take up to 48 hours, as certain precursors of carrageenan (μ- and ν-carrageenan) are converted into κ- and ι-carrageenan and thus strengthen the functional effect. The solution is then filtered to remove the remaining algae components. To obtain the carrageenan from the solution, the carrageenan is either precipitated using alcohol or gelled using potassium chloride and then squeezed out. The carrageenan obtained is then dried and ground. Chondrus , Eucheuma and Gigartina species are mainly used as sources of algae . A large part of the algae is now obtained in algae farms in the coastal waters off Zanzibar and in those of the Philippines . The species Eucheuma spinosum and Eucheuma cottonii are mainly used, as particularly pure types of carrage can be obtained from these species ( food additive E 407a).
Types
Even if mainly κ-, ι- and λ-carrageenan are of commercial interest, other types also occur in the algae. Two types are μ- and ν-carrageenan, which are precursors to κ- and ι-carrageenan and are converted into them during extraction. The proportion of carrageenan types in the finished carrageenan depends on the type of algae used and on the manufacturing process. Commercial carrageenans are never purely individual types.
κ-carrageenan
κ-carrageenan gels with potassium ions to form a firm and brittle gel and with calcium ions to form a firm, elastic and poor syneresis gel . It is only soluble in cold water as the sodium salt . As the calcium or potassium salt, significantly higher temperatures are required to completely dissolve the carrageenan. As it cools down, the carrageenan changes from a ball shape to a helix structure . With further cooling, the interaction with the calcium or potassium ions leads to the coalescence of the helices and thus the formation of a network.
κ-carrageenan also has a high milk reactivity. For this reason, even small amounts of carrageenan are sufficient to stabilize chocolate / cocoa beverages and prevent the cocoa particles from selling. This milk reactivity is due to the interactions of the negatively charged hydrocolloid with certain parts of the casein .
Below the isoelectric point of the protein, its charge changes and the carrageenan is precipitated from the protein.
For this reason, there are almost no sour milk products that are stabilized with carrageenan. In addition to interactions with milk protein κ-carrageenan shows synergism with tara gum , locust bean gum and Konjacgel . This generally leads to a strengthening of the gel structure and to melting and gel points that are shifted to higher temperatures.
ι-carrageenan
ι-carrageenan gels with calcium and is often used for dressings or softer gels. Ι-carrageenan is only cold-soluble as the sodium salt and, as the calcium or potassium form, also requires higher temperatures. When the hot carrageenan solution cools down, helixes are formed (similar to κ-carrageenan), with these helices forming a network via calcium bridges.
λ-carrageenan
λ-carrageenan does not form gels and is very soluble both cold and hot. This carrageenan is often used in the field of instant products, where no heating should take place. λ-carrageenan does not form any helical structures on cooling.
Applications
In the food industry, carrageenan is used as a temperature- resistant gelling agent and emulsifier for slimming products, light products and in meat products (e.g. sausage and marinades for grilled meat), and as a thickening agent in jams , baby food , dairy products, milkshakes , ice cream and desserts . With the help of carrageenan, cloudiness in wines can be eliminated or the formation of grease plugs ( creaming ) can be avoided in the case of cream filled in bottles.
In the EU it is approved as a food additive and thickener with the number E 407. Carrageenan is used in the cosmetics industry ( toothpaste ). According to the European Organic Regulation , it is approved for organic food . Partially degraded carrageenan is used as poligeenan in X-ray contrast media as a viscous chelator .
health
Carrageenan was rated as harmless by the FAO , the World Health Organization and the American FDA , but a permitted daily dose of 75 mg per kg body weight was set.
In animal experiments, ulcerations and changes in the immune system were found with degraded carrageenan. If carrageenan is tempered at high temperatures and at a low pH value , degraded carrageenan is produced. The longer the heating lasts, the more the carrageenan is broken down. In response to the study, the EU has extended its recommended consumption for carrageenan from a maximum of 0–75 mg per kg body weight per day to include the addition that no more than 5% of the molecular mass of carrageenan should be below 50 kDa in food .
Carrageenan is excreted unchanged by the body and can hinder the absorption of other food ingredients. It is suspected of causing allergy-like effects in people with predisposition .
In 2006, a study showed significant, as yet not fully explained, antiviral activity against human papillomaviruses , which can cause cervical cancer .
Some work shows that carrageenan has an indirect influence on the body's immune system by controlling the activity of macrophages .
In animal experiments, previously heated carrageenan had a negative impact on the digestive tract.
literature
- Y. Uno, T. Omoto, Y. Goto, I. Asai, M. Nakamura, T. Maitani: Molecular weight distribution of carrageenans studies by a combined gel permeation / inductively coupled plasma (GPC / ICP) method. In: Food Additives and Contaminants . 18.2001, pp. 763-772. London, ISSN 0265-203X
Web links
- Carrageenan additives database
- London South Bank University: Carrageenan (English)
- Opinion of the Scientific Committee on Food on Carrageenan (PDF; 156 kB; English)
- Report: Nina Rathfelder: Sick additive? Carrageenan in many foods , SWR - market check from January 15, 2019
Individual evidence
- ↑ NDR: The Tricks with Milk and Cheese (from 41m39s).
- ↑ Barbara Hirl: Grilled meat: What's under the marinade? , SWR - market check from June 19, 2018.
- ↑ a b carrageenan . Additives database, accessed August 4, 2009.
- ↑ JK Tobacman: Review of harmful gastrointestinal effects of carrageenan in animal experiments. In: Environ Health Perspect . Research Triangle Park NC 109.2001,10,983. PMC 1242073 (free full text).
- ^ Opinion of the Scientific Committee on Food on Carrageenan . (PDF; 160 kB) Scientific Committee on Food of the European Commission , March 5, 2003.
- ↑ Christopher B. Buck, Cynthia D. Thompson, Jeffrey N. Roberts, Martin Müller, Douglas R. Lowy, John T. Schiller: Carrageenan is a potent inhibitor of papillomavirus infection. In: PLoS Pathogens . 2.2006,7, p. E69, doi: 10.1371 / journal.ppat.0020069 , San Francisco.
- Jump up ↑ LJ Fidler et al .: Involvement of Macrophages in the Eradication of Established Metastases following Intravenous Injection of Liposomes Containing Macrophage Activators . In: Cancer Research , 42, 1982, pp. 496-501.
- ↑ VM Rumjanek et al .: A re-evaluation of the role of macrophages in carrageenan-induced immunosuppression. In: Immunology , 1977 September, 33 (3), pp. 423-432, PMC 1445637 (free full text).
- ↑ Phillip J. Catanzaro et al .: Spectrum and Possible Mechanism of Carrageenan Cytotoxicity. In: Am J Pathol , 1971 August, 64 (2), pp. 387-404, PMC 2047576 (free full text).
