Researchers derive potential food source from non-food plants

Researchers at Virginia Tech University, US, have successfully converted cellulose into starch, a process which could help in the extraction of untapped nutrients from plants which are not traditionally used as food crops.

Cellulose is the supporting material in plant cell walls and is the most common carbohydrate on earth, while starch is a key component in the human diet, representing 20%-40% of the daily caloric intake.

The research was conducted by a team led by YH Percival Zhang, an associate professor of biological systems engineering at the College of Agriculture and Life Sciences and the College of Engineering.

For the study, the team used a new process involving cascading enzymes to transform cellulose into amylose starch – a linear resistant starch that is not broken down during digestion.

Amylose starch is a good source of dietary fibre and can help decrease the risk of obesity and diabetes.

The new method uses cellulose from non-food plant material, such as corn stover – which comprises the stem, leaves and husk of the corn plant remaining after ears of corn are harvested.

The process transforms about 30% to amylose, and hydrolyses the remainder to glucose suitable for ethanol production.

Zhang said that cellulose and starch have the same chemical formula, but different chemical linkages.

"Our idea is to use an enzyme cascade to break up the bonds in cellulose, enabling their reconfiguration as starch," Zhang added.

While corn stover was used for the study, the researchers noted that a bioprocess called ‘simultaneous enzymatic biotransformation and microbial fermentation’ can be used to derive starch from any plant cellulose.

The bioprocess, which is covered under a provisional patent application, can be easily scaled up for commercial production, and is environmentally friendly as it does not require expensive equipment, heat, or chemical reagents, and does not produce any waste.

This study paves way for the capability to develop food from any plant, lowering the need for crops to be grown on valuable land that requires fertilisers, pesticides and large quantities of water.

The project could help address the dietary needs of a growing global population that is estimated to increase to nine billion by 2050.

Zhang said that apart from serving as a food source, the starch could be used in the manufacture of edible, clear films for biodegradable food packaging.

"It can even serve as a high-density hydrogen storage carrier that could solve problems related to hydrogen storage and distribution," Zhang added.

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Image: YH Percival Zhang led a team of researchers that has succeeded in transforming cellulose into starch. Photo courtesy of Virginia Polytechnic Institute and State University.