Eggshell: Difference between revisions
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An '''eggshell''' is the outer covering of a hard-shelled [[egg (biology)|egg]] and of some forms of eggs with soft outer coats. Bird eggshells contain calcium carbonate and dissolve in various acids, including the vinegar used in cooking. While dissolving the calcium carbonate in an egg shell reacts with the acid to form carbon dioxide. <ref>http://van.physics.illinois.edu/qa/listing.php?id=461</ref> |
An '''eggshell''' is the outer covering of a hard-shelled [[egg (biology)|egg]] and of some forms of eggs with soft outer coats. Bird eggshells contain calcium carbonate and dissolve in various acids, including the vinegar used in cooking. While dissolving the calcium carbonate in an egg shell reacts with the acid to form carbon dioxide. <ref>http://van.physics.illinois.edu/qa/listing.php?id=461</ref> |
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--[[Special:Contributions/65.32.119.143|65.32.119.143]] ([[User talk:65.32.119.143|talk]]) 00:50, 10 October 2012 (UTC)--[[Special:Contributions/65.32.119.143|65.32.119.143]] ([[User talk:65.32.119.143|talk]]) 00:50, 10 October 2012 (UTC)[[Girlsgogames.com]]ῤi m |
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== Diversity == |
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[[Image:Eggs green brown on end.jpg|thumb|200px|Some other colors of chicken eggs]] |
[[Image:Eggs green brown on end.jpg|thumb|200px|Some other colors of chicken eggs]] |
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The [[bird]] egg is a fertilized (or, in the case of some birds [such as chickens] possibly unfertilized) [[gamete]] located on the yolk surface and surrounded by [[albumen]], or egg white. The albumen in turn is surrounded by two shell membranes (inner and outer membranes) and then the eggshell. The chicken eggshell is 95-97% [[calcium carbonate]] crystals, which are stabilized by a protein matrix.<ref>{{cite journal |last1=Arias |first1=J. L. |last2=Fernandez |first2=M. S. |title=Role of extracellular matrix molecules in shell formation and structure |journal=World's Poultry Science Journal |volume=57 |pages=349–357 |year=2001 |doi=10.1079/WPS20010024}}</ref><ref>{{cite journal |last1=Nys |first1=Yves |last2=Gautron |first2=Joël |last3=Garcia-Ruiz |first3=Juan M. |last4=Hincke |first4=Maxwell T. |title=Avian eggshell mineralization: biochemical and functional characterization of matrix proteins |journal=Comptes Rendus Palevol |volume=3 |pages=549–62 |year=2004 |doi=10.1016/j.crpv.2004.08.002}}</ref><ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71.">{{cite journal |last1=Hunton |first1=P |title=Research on eggshell structure and quality: an historical overview |journal=Revista Brasileira de Ciência Avícola |volume=7 |pages=67–71 |year=2005 |doi=10.1590/S1516-635X2005000200001}}</ref> Without the protein, the crystal structure would be too brittle to keep its form and the organic matrix is thought to have a role in deposition of calcium during the mineralization process.<ref>Romanoff, A.L., A.J. Romanoff (1949) The avian egg. New York, Wiley.</ref><ref>Burley, R.W., D.V. Vadehra (1989) The Avian Egg: Chemistry and Biology. New York, Wiley.</ref><ref name="Lavelin, I., N. Meiri, M. Pines (2000) New insight in eggshell formation. Poult Sci 79: 1014–1017.">{{cite journal |last1=Lavelin |first1=I |last2=Meiri |first2=N |last3=Pines |first3=M |title=New insight in eggshell formation |journal=Poultry science |volume=79 |issue=7 |pages=1014–7 |year=2000 |pmid=10901204}}</ref> The structure and composition of the avian eggshell serves to protect the egg against damage and microbial contamination, prevention of desiccation, regulation of gas and water exchange for the growing embryo, and provides calcium for [[embryogenesis]]. Eggshell formation requires gram amounts of calcium being deposited within hours, which must be supplied via the hen’s diet.<ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71." /> |
The [[bird]] egg is a fertilized (or, in the case of some birds [such as chickens] possibly unfertilized) [[gamete]] located on the yolk surface and surrounded by [[albumen]], or egg white. The albumen in turn is surrounded by two shell membranes (inner and outer membranes) and then the eggshell. The chicken eggshell is 95-97% [[calcium carbonate]] crystals, which are stabilized by a protein matrix.<ref>{{cite journal |last1=Arias |first1=J. L. |last2=Fernandez |first2=M. S. |title=Role of extracellular matrix molecules in shell formation and structure |journal=World's Poultry Science Journal |volume=57 |pages=349–357 |year=2001 |doi=10.1079/WPS20010024}}</ref><ref>{{cite journal |last1=Nys |first1=Yves |last2=Gautron |first2=Joël |last3=Garcia-Ruiz |first3=Juan M. |last4=Hincke |first4=Maxwell T. |title=Avian eggshell mineralization: biochemical and functional characterization of matrix proteins |journal=Comptes Rendus Palevol |volume=3 |pages=549–62 |year=2004 |doi=10.1016/j.crpv.2004.08.002}}</ref><ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71.">{{cite journal |last1=Hunton |first1=P |title=Research on eggshell structure and quality: an historical overview |journal=Revista Brasileira de Ciência Avícola |volume=7 |pages=67–71 |year=2005 |doi=10.1590/S1516-635X2005000200001}}</ref> Without the protein, the crystal structure would be too brittle to keep its form and the organic matrix is thought to have a role in deposition of calcium during the mineralization process.<ref>Romanoff, A.L., A.J. Romanoff (1949) The avian egg. New York, Wiley.</ref><ref>Burley, R.W., D.V. Vadehra (1989) The Avian Egg: Chemistry and Biology. New York, Wiley.</ref><ref name="Lavelin, I., N. Meiri, M. Pines (2000) New insight in eggshell formation. Poult Sci 79: 1014–1017.">{{cite journal |last1=Lavelin |first1=I |last2=Meiri |first2=N |last3=Pines |first3=M |title=New insight in eggshell formation |journal=Poultry science |volume=79 |issue=7 |pages=1014–7 |year=2000 |pmid=10901204}}</ref> The structure and composition of the avian eggshell serves to protect the egg against damage and microbial contamination, prevention of desiccation, regulation of gas and water exchange for the growing embryo, and provides calcium for [[embryogenesis]]. Eggshell formation requires gram amounts of calcium being deposited within hours, which must be supplied via the hen’s diet.<ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71." /> |
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The fibrous chicken shell membranes are added in the proximal(white) isthmus of the [[oviduct]].<ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71." /> In the distal (red) isthmus mammillae or mammillary knobs are deposited on the surface of the outer membrane in a regular array pattern.<ref>{{cite journal |last1=Wyburn |first1=GM |last2=Johnston |first2=HS |last3=Draper |first3=MH |last4=Davidson |first4=MF |title=The ultrastructure of the shell forming region of the oviduct and the development of the shell of Gallus domesticus |journal=Quarterly journal of experimental physiology and cognate medical sciences |volume=58 |issue=2 |pages=143–51 |year=1973 |pmid=4487964}}</ref><ref>{{cite journal |last1=Fernandez |first1=MS |last2=Araya |first2=M |last3=Arias |first3=JL |title=Eggshells are shaped by a precise spatio-temporal arrangement of sequentially deposited macromolecules |journal=Matrix biology |volume=16 |issue=1 |pages=13–20 |year=1997 |pmid=9181550}}</ref> The mammillae are proteoglycan-rich and are thought to control calcification. In the shell gland (similar to a mammalian uterus), mineralization starts at the mammillae. The shell gland fluid contains very high levels of calcium and hydrogen carbonate. The thick calcified layer |
The fibrous chicken shell membranes are added in the proximal(white) isthmus of the [[oviduct]].<ref name="Hunton, P. Rev. Bras. 2005, 7(2), 67-71." /> In the distal (red) isthmus mammillae or mammillary knobs are deposited on the surface of the outer membrane in a regular array pattern.<ref>{{cite journal |last1=Wyburn |first1=GM |last2=Johnston |first2=HS |last3=Draper |first3=MH |last4=Davidson |first4=MF |title=The ultrastructure of the shell forming region of the oviduct and the development of the shell of Gallus domesticus |journal=Quarterly journal of experimental physiology and cognate medical sciences |volume=58 |issue=2 |pages=143–51 |year=1973 |pmid=4487964}}</ref><ref>{{cite journal |last1=Fernandez |first1=MS |last2=Araya |first2=M |last3=Arias |first3=JL |title=Eggshells are shaped by a precise spatio-temporal arrangement of sequentially deposited macromolecules |journal=Matrix biology |volume=16 |issue=1 |pages=13–20 |year=1997 |pmid=9181550}}</ref> The mammillae are proteoglycan-rich and are thought to control calcification. In the shell gland (similar to a mammalian uterus), mineralization starts at the mammillae. The shell gland fluid contains very high levels of calcium and hydrogen carbonate. The thick calcified layer ofi destiny |
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While the bulk of eggshell is made of calcium carbonate, it is now thought that the protein matrix has an important role to play in eggshell strength.<ref>http://ict.udg.co.cu/FTPDocumentos/Literatura%20Cientifica/Maestria%20Nutricion%20Animal/6.%20EVENTOS%20RELEVANTES/XVII%20Congreso%20Avicultura/confs/hunton1.htm</ref> These proteins affect crystallization, which in turn affects the eggshell structure. Moreover, the concentration of eggshell proteins decreases over the life of the laying hen, as does eggshell strength. |
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In an average [[chicken|laying hen]], the process of shell formation takes around 20 hours. [[Pigment]]ation is added to the shell by [[wiktionary:Papillae|papillae]] lining the oviduct, coloring it any of a variety of colors and patterns depending on species. Since eggs are usually laid blunt end first, that end is subjected to most pressure during its passage and consequently shows the most color. |
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====Environmental issues==== |
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The US food industry generates 150,000 tones of shell waste a year.<ref>Hecht J: Eggshells break into collagen market. New Scientist 1999, 161:6-6.</ref> The disposal methods for waste eggshells are 26.6% as fertilizer, 21.1% as animal feed ingredients, 26.3% discarded in municipal dumps, and 15.8% used in other ways.<ref>Daengprok W, Garnjanagoonchorn W, Mine Y: Fermented pork sausage fortified with commercial or hen eggshell calcium lactate. Meat Science 2002, 62:199-204.</ref> Many landfills are unwilling to take the waste because the shells and the attached membrane attract vermin. Together the calcium carbonate eggshell and protein rich membrane are useless.<ref>Wei Z, Li B, Xu C: Application of waste eggshell as low-cost solid catalyst for biodiesel production [electronic resource]. Bioresource technology 2009, 100:2883-2885.</ref> Recent inventions have allowed for the egg cracking industry to separate the eggshell from the eggshell membrane. The eggshell is mostly made up of calcium carbonate and the membrane is valuable protein. When separated both products have an array of uses. |
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=== Mammal eggs === |
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=== Egg teeth === |
=== Egg teeth === |
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Hatching birds, amphibian and egg-laying reptiles have an [[egg tooth|egg-tooth]] used to start an exit hole in the hard eggshell.<ref>http://ag.ansc. |
Hatching birds, amphibian and egg-laying reptiles have an [[egg tooth|egg-tooth]] used to start an exit hole in the hard eggshell.<ref>http://ag.ansc.pu |
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== See also == |
== See also == |
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Revision as of 00:50, 10 October 2012
 | This article needs additional citations for verification. (February 2008) |
An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats. Bird eggshells contain calcium carbonate and dissolve in various acids, including the vinegar used in cooking. While dissolving the calcium carbonate in an egg shell reacts with the acid to form carbon dioxide. [1]
--65.32.119.143 (talk) 00:50, 10 October 2012 (UTC)--65.32.119.143 (talk) 00:50, 10 October 2012 (UTC)Girlsgogames.comῤi m
Insect eggs
Insects and other arthropods lay a variety of styles and shapes of eggs. Some have gelatinous or skin-like coverings, others have hard eggshells. Softer shells are mostly protein. It may be fibrous or quite liquid. Some arthropod eggs do not actually have shells, rather, their outer covering is actually the outermost embryonic membrane, the choroid, which serves to protect inner layers. The choroid itself can be a complex structure, and it may have different layers within it. It may have an outermost layer called an exochorion. Eggs which must survive in dry conditions usually have hard eggshells, made mostly of dehydrated or mineralized proteins with pore systems to allow respiration. Arthropod eggs can have extensive ornamentation on their outer surfaces.
Fish, amphibian and reptile eggs
Fish and amphibians generally lay eggs which are surrounded by the extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish and amphibian eggs have thick, leathery coats, especially if they must withstand physical force or desiccation. These type of eggs can also be very small and fragile.
While many reptiles lay eggs with flexible, calcified, eggshells, there are some that lay hard eggs. Eggs laid by snakes generally have leathery shells which often adhere to one another. Depending on the species, turtles and tortoises lay hard or soft eggs. Several species lay eggs which are nearly indistinguishable from bird eggs.
Bird eggs
The bird egg is a fertilized (or, in the case of some birds [such as chickens] possibly unfertilized) gamete located on the yolk surface and surrounded by albumen, or egg white. The albumen in turn is surrounded by two shell membranes (inner and outer membranes) and then the eggshell. The chicken eggshell is 95-97% calcium carbonate crystals, which are stabilized by a protein matrix.[2][3][4] Without the protein, the crystal structure would be too brittle to keep its form and the organic matrix is thought to have a role in deposition of calcium during the mineralization process.[5][6][7] The structure and composition of the avian eggshell serves to protect the egg against damage and microbial contamination, prevention of desiccation, regulation of gas and water exchange for the growing embryo, and provides calcium for embryogenesis. Eggshell formation requires gram amounts of calcium being deposited within hours, which must be supplied via the hen’s diet.[4]
The fibrous chicken shell membranes are added in the proximal(white) isthmus of the oviduct.[4] In the distal (red) isthmus mammillae or mammillary knobs are deposited on the surface of the outer membrane in a regular array pattern.[8][9] The mammillae are proteoglycan-rich and are thought to control calcification. In the shell gland (similar to a mammalian uterus), mineralization starts at the mammillae. The shell gland fluid contains very high levels of calcium and hydrogen carbonate. The thick calcified layer ofi destiny
bbbbbbbbbbbbbbbilar to those of reptiles. The shell is deposited on the egg in layers within the uterus. The egg can take up fluids and grow in size during this process, and the final, most rigid layer is not added until the egg is full-size.
Egg teeth
Hatching birds, amphibian and egg-laying reptiles have an egg-tooth used to start an exit hole in the hard eggshell.<ref>http://ag.ansc.pu
See also
- Eggshell skull rule, in tort law
- Walk on eggshells, an idiom in the English language
References
- ^ http://van.physics.illinois.edu/qa/listing.php?id=461
- ^ Arias, J. L.; Fernandez, M. S. (2001). "Role of extracellular matrix molecules in shell formation and structure". World's Poultry Science Journal. 57: 349–357. doi:10.1079/WPS20010024.
- ^ Nys, Yves; Gautron, Joël; Garcia-Ruiz, Juan M.; Hincke, Maxwell T. (2004). "Avian eggshell mineralization: biochemical and functional characterization of matrix proteins". Comptes Rendus Palevol. 3: 549–62. doi:10.1016/j.crpv.2004.08.002.
- ^ a b c Hunton, P (2005). "Research on eggshell structure and quality: an historical overview". Revista Brasileira de Ciência Avícola. 7: 67–71. doi:10.1590/S1516-635X2005000200001.
- ^ Romanoff, A.L., A.J. Romanoff (1949) The avian egg. New York, Wiley.
- ^ Burley, R.W., D.V. Vadehra (1989) The Avian Egg: Chemistry and Biology. New York, Wiley.
- ^ Lavelin, I; Meiri, N; Pines, M (2000). "New insight in eggshell formation". Poultry science. 79 (7): 1014–7. PMID 10901204.
- ^ Wyburn, GM; Johnston, HS; Draper, MH; Davidson, MF (1973). "The ultrastructure of the shell forming region of the oviduct and the development of the shell of Gallus domesticus". Quarterly journal of experimental physiology and cognate medical sciences. 58 (2): 143–51. PMID 4487964.
- ^ Fernandez, MS; Araya, M; Arias, JL (1997). "Eggshells are shaped by a precise spatio-temporal arrangement of sequentially deposited macromolecules". Matrix biology. 16 (1): 13–20. PMID 9181550.
Further reading
- Kilner, R. M. (2006). "The evolution of egg colour and patterning in birds". Biological Reviews. 81 (3): 383–406. doi:10.1017/S1464793106007044. PMID 16740199.