Zein

From Wikipedia, the free encyclopedia

Zein 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 most well understood plant proteins^[1] and has a variety of industrial and food uses.^[2] ^[3] Historically it has been used in the manufacture of a wide variety of commercial products including coatings for paper cups, soda bottle cap linings, clothing fabric^[4], buttons, adhesives, coatings and binders. Pure zein is clear, odorless, tasteless, hard, water-insoluble, and edible, making it invaluable 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" and used as a coating on bakery products ^[5]or as "vegetable protein." It is classified as GRAS (Generally Recognized as Safe) by the U.S. Food and Drug Administration.

Zein can be further processed into resins and other bioplastic polymers which can be extruded or rolled into a variety of plastic products.^[6] ^[7] With increasing environmental concerns about synthetic coatings (such as PFOA) and the currently higher prices of hydrocarbon based petrochemicals, there is increased focus on zein as a raw material for a variety of non-toxic and renewable polymer applications, particularly in paper industry applications.^[8] ^[9] 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 Wm. Wrigley Jr. Company have recently been studying the possibility of using zein to replace some of the gum base in chewing gum ^[10]. They are also studying medical applications such as using the zein molecule to "carry biocompounds to targeted sites in the human body". ^[11] 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. ^[12] Other packaging/food safety applications that have been researched include frozen foods,^[13], ready-to-eat chicken,^[14]and cheese and liquid eggs.^[15] Food researchers in Japan have noted the ability of the zein molecule to act as a water barrier.^[16]

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. Some believe the solution is to extract zein as a byproduct in the manufacturing process for ethanol^[17] or in new off-shore manufacture.