Zein

Zein is a class of prolamine protein found in maize (corn). It is usually manufactured as a powder from corn gluten meal. Zein is one of the best understood plant proteins.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, American Chemical Society Pure zein is clear, odorless, tasteless, hard, water-insoluble, and edible, and it has a variety of industrial and food uses.Lawton, John W.
Zein: A History of Processing and Use
, November 1, 2002, American Association of Cereal Chemists

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,Commission on Life Sciences
Biobased Industrial Products: Research and Commercialization Priorities
2002. 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". 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.Miyoshi, T., Toyohara, H., Minematsu, H.
Preparation of ultrafine fibrous zein membranes via electrospinning
, ''Polymer International'' Vol. 54, no. 8, 2005.Selling, G., Biswas, A., Patel, A., Walls, D., Dunlap, C., Wei, Y.
Impact of Solvent on Electrospinning of Zein and Analysis of Resulting Fibers
, ''Macromolecular Chemistry and Physics'' Vol. 208, no. 9, 2007. It can be used as a water and grease coating for paperboards and allows recyclability.

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 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.

Zein can be further processed into resins and other bioplastic polymers, which can be extruded or rolled into a variety of plastic products.Lee, Richard
Multiple-use Corn zein-based Biodegradable Resins, Sheets, and Films are an attractive alternative to plastic
, University of Illinois at Urbana-Champaign.Lawton Jr., J.W.
Plasticizers for Zein:their Effect on Tensile Properties and Water Absorption of Zein Films
January 12, 2004, ''Cereal Chemistry''. With increasing environmental concerns about synthetic coatings (such as PFOA) 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.Jabar, Anthony Jr; Bilodeau, Michael A.; Neivandt, David J.; Spender, Jonathan
Barrier Compositions and Articles Produced with the Compositions
, December 29, 2005, United States Patent (pending)Parris, Nicholas; Sykes, Marguerite; Dickey, Leland C.; Wiles, Jack L.; Urbanik, Thomas J.; Cooke, Peter H.
Recyclable zein-coated kraft paper
, ''Progress in paper recycling'' Vol. 11, no. 3, May 2002. 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.

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.McGowan B.A., Padua G.W., and Lee S-Y.
Formulation of Corn Zein Chewing Gum and Evaluation of Sensory Properties by the Time-Intensity Method
, September, 2005, ''Journal of Food Science''. They are also studying medical applications such as using the zein molecule to "carry biocompounds to targeted sites in the human body".Picklesimer, Phyllis.

" University of Illinois at Urbana-Champaign. 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.Bertrand, Kate,
Military packages put technology to the test
" September 2005 Other packaging/food safety applications that have been researched include frozen foods,Padua, Graciela W., Rakotonirainy, Andrianaivo, and Wang, Qin

, University of Illinois at Urbana-Champaign ready-to-eat chicken,Janes M.E.; Kooshesh S.; Johnson M.G.
Control of Listeria monocytogenes on the Surface of Refrigerated, Ready-to-eat Chicken Coated with Edible Zein Film
September, 2002, ''Journal of Food Science''. and cheese and liquid eggs.Dawson, Paul
Packaging Films Fight Bacteria and Help the Environment
Clemson University Food researchers in Japan have noted the ability of the zein molecule to act as a water barrier.Qiangxian Wu, Hiroshi Sakabe and Seiichiro Isobe
Studies on the toughness and water resistance of zein-based polymers by modification
June, 2003, National Food Research Institute, Japan.

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 ethanolCore, Jim.
Corn Protein Could Reduce Ethanol Production Costs
" April 15, 2002, United States Department of Agriculture Agricultural Research Service. or in new off-shore manufacture.

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. 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; 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. p.335

Other biodegradable polymers

*Cellophane
* Plastarch material
*Poly-3-hydroxybutyrate
*Polycaprolactone
*Polyglycolide
* Polylactic acid

References

External links

Freeman ZEIN

INVIZ
by POET

{{InterPro content, IPR002530

Seed storage proteins
Food additives
Biodegradable plastics
Protein families