Corn Research Kernels
Ken Hough, Director, Research and Market Development

Researchers with the USDA Agricultural Research Service (ARS) at the Eastern Regional Research Centre, Wyndmoor, Pennsylvania, are developing a zein (corn protein)-based, biodegradable coating to replace the wax on wax paper and other packaging used widely in the food industry. The current wax coating is made from refined petroleum products, which prevents these materials from being recycled, since the wax cannot easily be separated from the packaging.

Purified zein, currently derived from corn gluten meal (a by-product of corn wet milling), sells for about $7 U.S./lb. and is used primarily as an edible, water-resistant coating for nuts and confectionery products (market is less than $1 million U.S. per year). Aiming for lower recovery cost rather than the higher purity or high recovery efficiency of the traditional source, the ARS scientists have developed a new process to extract a zein-lipid (corn protein-oil) mixture from ground corn during ethanol manufacture. Their recovery cost is estimated to be about $1-2 U.S. per pound. Since zein is deficient in some of the important amino acids, and insoluble in water, it is not a valuable component in the feed co-product.

Zein comprises about 50% of corn protein (i.e., about 2.5 lb of zein per bushel of corn), and unlike other corn proteins which are water soluble, zein repels water. When coated on paper products, it provides good grease resistance and water barrier properties. Other potential uses are being investigated, including use as an adhesive or as a water resistant finish for single use products such as fast food packages, disposable diapers or tablecloths.
Further information is available at the USDA ARS Eastern Regional Research Centre web sites

http://www.arserrc.gov/es/ZeinExtraction.htm and http://www.arserrc.gov/es/Zein-Wax.htm.

"Egg-protein" Shows Promise for Insect-resistant Bio-engineered Grain

In research at the USDA ARS Grain Marketing and Production Research Centre in Manhattan, Kansas, scientists are studying corn genetically engineered to contain avidin, a common protein in egg white, for bio-control of stored grain insects. This research is being conducted in collaboration with Pioneer Hi-Bred International and ProdiGene of College Station, Texas, supplier of the bio-engineered avidin-corn.

Avidin restricts the availability of biotin, a common vitamin which is essential for insect growth and development. Fed on kernels of the bio-engineered corn containing 20 parts per million (ppm) of avidin, most grain moths and maize weevils died. Meal produced from avidin-corn, with more than 100 ppm avidin, killed the larvae of a broad selection of stored food insect pests, including lesser grain borers, red flour beetles, confused flour beetles, sawtoothed grain beetles, flat grain beetles, warehouse beetles, Indian meal moths and Mediterranean flour moths, indicating that products made from avidin-corn will have a longer shelf life.
This technology has potential for application in a variety of food and feed crops, including corn, wheat, rice and grain sorghum, and it could have important implications for production and storage of food and feed crops in lesser developed countries, where losses to storage insects are even more prevalent.

This bio-pesticide technology could provide an alternative to the stored grain insecticide methyl bromide, which pesticide regulatory agencies have high on their list to replace as soon as a suitable substitute can be registered, due to its high toxicity and potential to harm the earth's protective ozone layer. However, despite the fact that avidin is already a common protein in human diets, through egg white, the U.S. Food and Drug Administration will require a thorough risk assessment of avidin-corn before approving it as a food or feed product. (Similar scrutiny prior to approval would be expected in other countries as well).

There may be opportunities to utilize avidin-corn for other insect pests, providing protection from planting to storage. Avidin-corn could provide protection from a broader range of insects than Bt-corn does. Since only insects which actually feed on the avidin-corn would be controlled, beneficial and non-target organisms would not be affected. Molecular promoters could be used to trigger avidin production only in those tissues where protection might be needed, for example, not in the pollen but in the roots, stems, leaves or seeds. And unlike field-applied insecticides, the avidin-protection would not wash off, or be inactivated by ultraviolet light. Furthermore, avidin is biodegradable, and thus not a risk for contamination of soil or water.

Avidin extracted from chicken eggs is currently used in medical and biochemical kits as a diagnostic protein, and sells for about $3000 U.S. per gram. Produced from avidin-corn, as is now done by the Sigma- Aldrich chemical company in St. Louis, Missouri, this cost is reduced. Avidin-corn is now grown by U.S. farmers under contract with Stauffer Biotech in Aurora, Nebraska.

Further information is available at the USDA ARS Agricultural Research Magazine, on line at

http://www. ars.usda.gov/is/AR/archive/aug00/egg0800.htm.

1