The ancient Aztecs of Mexico developed a rich and complex culture, often remembered for its huge limestone monuments. Another contribution, just as lasting and more practical, is the Aztecs' alkaline process for producing corn tortillas.

A University of Nebraska researcher is using that same centuries-old process, little changed except for mechanization, to test the quality of tortillas made from Nebraska corn.

"Many scholars think that all of the successful ancient cultures in Latin America developed a process like this for corn," said David Jackson, Institute of Agriculture and Natural Resources food scientist. Research elsewhere indicates the process increases the availability of B vitamins and proteins in corn and decreases some toxins.

All corn and tortilla chip processing plants in the United States use the alkaline method for corn and tortilla chip production, but research requires a smaller-scale operation.

With a grant from the Mexican government, Jackson set up a small-scale alkaline processing plant in UNL's Filley Hall in late 1997, complete with the lava grindstones required for turning corn into masa. Masa is the dough used to make tortillas, tortilla chips, corn chips and taco shells. It's the last step in the alkaline cooking process.

In the alkaline process, whole kernel corn is soaked in near-boiling water containing 1 percent food grade lime - the alkaline part of the process - for 20 to 45 minutes. This mixture steeps overnight before water is drained off and the resulting soft corn, called nejayote, is washed to remove the outer covering of the kernels. This washed product, called nixtamal, is ground between two lava stones to produce masa.

It all begins with corn, an abundant Nebraska commodity. Matching Nebraska corn to Latin America's huge appetite for tortillas and chips would open a major market for the state's farmers.

Consumers prefer tortillas made from specialty white corn types with a harder kernel, Jackson said. Nebraska produces more white corn than any other state, almost 17 million bushels in 1998, or 20 percent of the U.S. crop. But yellow corn is still king - Nebraska produced 1.1 billion bushels in 1998. Latin American countries buy yellow corn, but it's too soft for their tastes.

"What happens now is that Latin American countries usually import U.S. No. 2 yellow corn, not specialty corn, and they hate it - it doesn't cook right, it's too yellow and it makes poorer quality tortillas," Jackson said. Most U.S. specialty corn goes into the domestic chip and tortilla market.

Is there a way to make good tortillas out of the more common yellow corn? Jackson is cooking up the answers in his processing plant.

His first project in the new plant involved gathering yield information for the Mexican government. He cooked Mexican corn samples to determine how many kilograms of tortillas can be produced from 1 kilogram of corn. Jackson varied the method, using different cooking times and amounts of lime and water. Using sophisticated statistical analyses, he created three-dimensional graphs depicting various combinations and indicating which gives the best and most tortillas.

He's using these same techniques in new research focusing on Nebraska corn. In this one-year, Nebraska Corn Board-funded project, he'll test the cooking quality of both hard-kerneled white corn and the softer No. 2 corn.

"We want to prove to Latin America that we have specialty corn that will make the products they want, but they will have to pay a premium for it," Jackson said.

Finding ways to alter the alkaline process to produce better tortillas from No. 2 corn is a key part of this work.

"If Latin American countries buy the cheaper No. 2 corn, we want to be able to give them processing information that will help make a better product."

- Monica Manton Norby

Food Scientist David Jackson makes tortillas and tortilla chips from Nebraska corn using a small-scale alkaline processing plant in his lab. Jackson feeds corn, softened through alkaline processing, into a grinder.

Lava stones grind corn into masa, the dough used to make tortillas, tortilla chips, corn chips and taco shells. The alkaline process is a centuries-old process, little changed except for mechanization.

Freshly ground masa dough is prepared to be made into tortillas and tortilla chips.

Masa comes out of the sheeter, a machine that cuts the dough into tortilla chip shapes, and moves via conveyer belt into the oven.

Research Technician Maria Buendia Gonzalez and Jackson inspect a fresh batch of tortillas.