Corn Husks for Dinner: Inedible Plant Cellulose Transformed into Starch

Feel like eating raw bamboo? How about that corn husk? These ingredients may not exactly sound appealing, but researchers may have a way to make them more palatable. A team of researchers has successfully transformed cellulose into starch, a process that has the potential to provide a previously untapped nutrient source from plants not traditionally thought of as food crops.

Starch is one of the most important components of the human diet, providing 20 to 40 percent of our caloric intake each day. As the global population grows, finding enough food to feed the 9 billion people expected by 2050 will take novel new methods of food production. It's therefore not surprising that researchers turned to cellulose for their answer.

Cellulose, which is the supporting material in plant cell walls, is the most common carbohydrate on Earth. Yet it is difficult for humans to metabolize, which is what prompted the current research into converting the cellulose into another form of starch, called amylose. This linear resistant starch is not broken down in the digestion process and instead acts as a good source of dietary fiber. It's been shown to decrease the risk of obesity and diabetes.

In order to actually convert cellulose into amylose, the researchers used a novel method involving cascading enzymes. The difference between the two starches is slight--they possess the same chemical formula, but have different chemical linkages. The enzyme cascade allowed researchers to break up the bonds in cellulose and then reconfigure them as starch.

The bioprocess itself has been labeled "simultaneous enzymatic biotransformation and microbial fermentation" and is easy to scale up for commercial production. It could potentially be used with corn stover, which consists of the stem, leaves and husk of the corn plant that remain after the ears of the corn have been harvested.

"Besides serving as a food source, the starch can be used in the manufacture of edible, clear films for biodegradable food packaging," said Y.H. Percival Zhang, an associate professor of biological systems engineering in the College of Agriculture and Life Sciences and the College of Engineering in a press release. "It can even serve as a high-density hydrogen storage carrier that could solve problems related to hydrogen storage and distribution."

The details of this new technique are published in the Proceedings of the National Academy of Sciences.