Zein

{{Short description|Proteins found in maize (corn)}} {{other uses}} {{Use mdy dates|date=February 2012}} {{Infobox protein family | Symbol = Zein | Name = Zein | image = | width = | = | Pfam = PF01559 | Pfam_clan = | InterPro = IPR002530 | SMART = | PROSITE = | MEROPS = | SCOP = | TCDB = | OPM family = | OPM protein = | CAZy = | CDD = }} '''Zein''' ({{IPAc-en||ˈ|z|iː|ɪ|n}} {{respell|ZEE|in}}) is a class of prolamine protein found in maize. It is usually manufactured as a powder from corn gluten meal. Zein is one of the best understood plant proteins.<ref name="momany">Momany, Frank A.; Sessa, David J.; Lawton, John C.; Selling, Gordon W.; Hamaker, Sharon A. H.; and Willett, Julious L. "Structural Characterization of A-Zein" December 27, 2005, ''J. Agric. Food Chem.'' {{doi|10.1021/jf058135h}}</ref> Pure zein is clear, odorless, tasteless, hard, water-insoluble, and edible, and it has a variety of industrial and food uses.<ref name="lawton2002">Lawton, John W. "[http://199.86.26.71/cerealchemistry/articles/2002/1203-01R.pdf Zein: A History of Processing and Use] {{Webarchive|url=https://web.archive.org/web/20061103015300/http://199.86.26.71/cerealchemistry/articles/2002/1203-01R.pdf |date=November 3, 2006 }}", November 1, 2002, American Association of Cereal Chemists</ref><ref name="gennadios">{{cite book|editor-last=Gennadios|editor-first= Aristippos |title = Protein-Based Films and Coatings|date =2002|publisher = CRC Press|url = https://books.google.com/books?id=r4_MBQAAQBAJ |isbn = 9781420031980}}</ref>

==Commercial uses== Historically, zein has been used in the manufacture of a wide variety of commercial products, including coatings for paper cups, soda bottle cap linings, clothing fabric,<ref name="commission on life sciences">Commission on Life Sciences "[http://www.nap.edu/openbook/0309053927/html/35.html Biobased Industrial Products: Research and Commercialization Priorities]" 2002.</ref> buttons, adhesives, coatings and binders. The dominant historical use of zein was in the textile fibers market where it was produced under the name "Vicara".<ref name="lawton2002"/><ref name="Horst">{{cite journal|last=ter Horst|first= W.P. |journal =Am Dyestuff Rep|volume= 38|page = P335|date= 1949|title = Vicara — New Fiber Derived From Zein}}</ref> With the development of synthetic alternatives, the use of zein in this market eventually disappeared. By using electrospinning, zein fibers have again been produced in the lab, where additional research will be performed to re-enter the fiber market.<ref name="Miyoshi">Miyoshi, T., Toyohara, H., Minematsu, H. "[https://archive.today/20121216141727/http://www3.interscience.wiley.com/cgi-bin/abstract/110481790/ABSTRACT Preparation of ultrafine fibrous zein membranes via electrospinning]", ''Polymer International'' Vol. 54, no. 8, 2005.</ref><ref name="Selling">Selling, G., Biswas, A., Patel, A., Walls, D., Dunlap, C., Wei, Y. "[https://archive.today/20121216144506/http://www3.interscience.wiley.com/cgi-bin/abstract/114229013/ABSTRACT Impact of Solvent on Electrospinning of Zein and Analysis of Resulting Fibers]", ''Macromolecular Chemistry and Physics'' Vol. 208, no. 9, 2007.</ref> It can be used as a water and grease resistant coating for paperboards and allows recyclability.<ref name="parris">Parris, Nicholas; Sykes, Marguerite; Dickey, Leland C.; Wiles, Jack L.; Urbanik, Thomas J.; Cooke, Peter H. "[http://www.treesearch.fs.fed.us/pubs/8583 Recyclable zein-coated kraft paper] {{Webarchive|url=https://web.archive.org/web/20060223204648/http://www.treesearch.fs.fed.us/pubs/8583 |date=February 23, 2006 }}", ''Progress in paper recycling'' Vol. 11, no. 3, May 2002.</ref>

Zein's properties make it valuable in processed foods and pharmaceuticals, in competition with insect shellac. It is now used as a coating for candy, nuts, fruit, pills, and other encapsulated foods and drugs. In the United States, it may be labeled as "confectioner's glaze" (which may also refer to shellac-based glazes) and used as a coating on bakery products<ref name="kobs">{{cite web|last =Kobs|first= Lisa |url = https://www.naturalproductsinsider.com/specialty-nutrients/shining-appearances |title= Shining Up Appearances|website = Natural Products Insider|date = May 2000}}</ref> or as "vegetable protein." It is classified as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration. For pharmaceutical coating, zein is preferred over food shellac, since it is all natural and requires less testing per the USP monographs.{{Citation needed|date=January 2021}}

Zein can be further processed into resins and other bioplastic polymers, which can be extruded or rolled into a variety of plastic products.<ref name="lee">Lee, Richard "[http://www.otm.uiuc.edu/techs/techdetail.asp?id=259 Multiple-use Corn zein-based Biodegradable Resins, Sheets, and Films are an attractive alternative to plastic] {{Webarchive|url=https://web.archive.org/web/20060330081245/http://www.otm.uiuc.edu/techs/techdetail.asp?id=259 |date=March 30, 2006 }}", University of Illinois at Urbana-Champaign.</ref><ref name="lawton">Lawton Jr., J.W. "[http://199.133.10.189/research/publications/publications.htm?SEQ_NO_115=142776 Plasticizers for Zein:their Effect on Tensile Properties and Water Absorption of Zein Films] {{Webarchive|url=https://web.archive.org/web/20070929132353/http://199.133.10.189/research/publications/publications.htm?SEQ_NO_115=142776 |date=September 29, 2007 }}" January 12, 2004, ''Cereal Chemistry''.</ref> With increasing environmental concerns about synthetic coatings and the current higher prices of hydrocarbon-based petrochemicals, there is increased focus on zein as a raw material for a variety of nontoxic and renewable polymer applications, particularly in the paper industry.<ref name="jabar">Jabar, Anthony Jr; Bilodeau, Michael A.; Neivandt, David J.; Spender, Jonathan "[http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2006002346&F=0 Barrier Compositions and Articles Produced with the Compositions] {{Webarchive|url=https://web.archive.org/web/20080917212546/http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=WO2006002346&F=0 |date=September 17, 2008 }}", December 29, 2005, United States Patent (pending)</ref><ref name="parris"/> Other reasons for a renewed interest in zein include concern about the landfill costs of plastics, and consumer interest in natural substances. There are also a number of potential new food industry applications.{{Citation needed|date=January 2021}}

Researchers at the University of Illinois at Urbana-Champaign and at William Wrigley Jr. Company have recently been studying the possibility of using zein to replace some of the gum base in chewing gum.<ref name="mcgowan">McGowan B.A., Padua G.W., and Lee S-Y. "[http://lib3.dss.go.th/fulltext/Journal/Journal%20of%20food%20science/2005%20v.70/no.7/26466jfsv70n7pS0475-0481ms20040742%5B1%5D.pdf Formulation of Corn Zein Chewing Gum and Evaluation of Sensory Properties by the Time-Intensity Method]", September, 2005, ''Journal of Food Science''.</ref> They are also studying medical applications such as using the zein molecule to "carry biocompounds to targeted sites in the human body".<ref name="picklesimer">Picklesimer, Phyllis. "[http://www.news.uiuc.edu/ii/05/0317/nano.html Nanotechnologist Plans to Build Things with Bricklike Corn Molecules] {{Webarchive|url=https://web.archive.org/web/20080719221612/http://www.news.uiuc.edu/ii/05/0317/nano.html |date=July 19, 2008 }}," University of Illinois at Urbana-Champaign.</ref> There are a number of potential food safety applications that may be possible for zein-based packaging according to several researchers. A military contractor is researching the use of zein to protect MRE food packages.<ref name="mrezien">Bertrand, Kate, "[http://www.fdp.com/content.php?s=FP/2005/09&p=15 Military packages put technology to the test]," September 2005</ref> Other packaging/food safety applications that have been researched include frozen foods,<ref name="padua">Padua, Graciela W., Rakotonirainy, Andrianaivo, and Wang, Qin "[http://www.aces.uiuc.edu/~biobased/Publications/Biopack-paper.html Zein-Based Biodegradable Packaging for Frozen Foods] {{Webarchive|url=https://web.archive.org/web/20060227112037/http://www.aces.uiuc.edu/~biobased/Publications/Biopack-paper.html |date=February 27, 2006 }}", University of Illinois at Urbana-Champaign</ref> ready-to-eat chicken,<ref name="janes">Janes M.E.; Kooshesh S.; Johnson M.G. "[http://bookstore.ift.org/store/iftstore/newstore.cgi?categoryid=556&categoryparent=556&itemid=20272&view=item Control of Listeria monocytogenes on the Surface of Refrigerated, Ready-to-eat Chicken Coated with Edible Zein Film] {{Webarchive|url=https://web.archive.org/web/20150722092939/http://bookstore.ift.org/store/iftstore/newstore.cgi?categoryid=556&categoryparent=556&itemid=20272&view=item |date=July 22, 2015 }}" September, 2002, ''Journal of Food Science''.</ref> and cheese and liquid eggs.<ref name="dawson">Dawson, Paul "[http://www.clemson.edu/scg/food/pkgfilm.htm Packaging Films Fight Bacteria and Help the Environment] {{Webarchive|url=https://web.archive.org/web/20060924043001/http://www.clemson.edu/scg/food/pkgfilm.htm |date=September 24, 2006 }}" Clemson University</ref> Food researchers in Japan have noted the ability of the zein molecule to act as a water barrier.<ref name="quiangzian">Qiangxian Wu, Hiroshi Sakabe and Seiichiro Isobe "[https://web.archive.org/web/20080111143526/http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TXW-48NJ38B-2&_coverDate=06%2F30%2F2003&_alid=371882069&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5601&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=cc2901ad554a5aaac9a885d88237a6fb Studies on the toughness and water resistance of zein-based polymers by modification]" June, 2003, National Food Research Institute, Japan.</ref>

While there are numerous existing and potential uses for zein, the main barrier to greater commercial success has been its historic high cost until recently. Zein pricing is now very competitive with food shellac. Zein may be extracted as a byproduct in the manufacturing process for ethanol<ref name="core">Core, Jim. "[https://www.ars.usda.gov/news-events/news/research-news/2002/corn-protein-could-reduce-ethanol-production-costs/ Corn Protein Could Reduce Ethanol Production Costs]," April 15, 2002, United States Department of Agriculture Agricultural Research Service.</ref> or in new off-shore manufacture.{{Citation needed|date=January 2021}}

==Gene family==

Alpha-prolamins are the major seed storage proteins of species of the grass tribe Andropogoneae. They are unusually rich in glutamine, proline, alanine, and leucine residues and their sequences show a series of tandem repeats presumed to be the result of multiple intragenic duplication.<ref name="pmid8451243">{{cite journal |vauthors=Garratt R, Oliva G, Caracelli I, Leite A, Arruda P | title = Studies of the zein-like alpha-prolamins based on an analysis of amino acid sequences: implications for their evolution and three-dimensional structure | journal = Proteins | volume = 15 | issue = 1 | pages = 88–99 |date=January 1993 | pmid = 8451243 | doi = 10.1002/prot.340150111 | s2cid = 32504936 }}</ref> In ''Zea mays'' (Maize), the 22 kDa and 19 kDa zeins are encoded by a large multigene family and are the major seed storage proteins accounting for 70% of the total zein fraction. Structurally the 22 kDa and 19 kDa zeins are composed of nine adjacent, topologically antiparallel helices clustered within a distorted cylinder. The 22 kDa alpha-zeins are encoded by 23 genes;<ref name="pmid11691845">{{cite journal |vauthors=Song R, Llaca V, Linton E, Messing J | title = Sequence, regulation, and evolution of the maize 22-kD alpha zein gene family | journal = Genome Res. | volume = 11 | issue = 11 | pages = 1817–25 |date=November 2001 | pmid = 11691845 | pmc = 311139 | doi = 10.1101/gr.197301 }}</ref> twenty-two of the members are found in a roughly tandem array forming a dense gene cluster. The expressed genes in the cluster are interspersed with nonexpressed genes. Some of the expressed genes differ in their transcriptional regulation. Gene amplification appears to be in blocks of genes explaining the rapid and compact expansion of the cluster during the evolution of maize.<ref name="Schnable-2015">{{cite journal | last=Schnable | first=James C. | title=Genome Evolution in Maize: From Genomes Back to Genes | journal=Annual Review of Plant Biology | publisher=Annual Reviews | volume=66 | issue=1 | date=2015-04-29 | issn=1543-5008 | doi=10.1146/annurev-arplant-043014-115604 | pages=329–343| pmid=25494463 | doi-access=free | bibcode=2015AnRPB..66..329S }} p.{{spaces}}335</ref>

== Other biodegradable polymers== *Cellophane *Plastarch material *Poly-3-hydroxybutyrate *Polycaprolactone *Polyglycolide *Polylactic acid

== References == {{Reflist|2}}

== External links ==

{{InterPro content|IPR002530}}

Category:Seed storage proteins Category:Food additives Category:Biodegradable plastics Category:Protein families