Wood: It's What's for Dinner
Cellulose, the main ingredient in wood, is one of the most abundant organic compounds on Earth. Scientists in Virginia have discovered a way to turn cellulose into starch, the most common carbohydrate in the human diet. Their findings are documented in the Proceedings of the National Academy of Sciences and were published online Tuesday. As a bonus, the leftover from the process is ethanol, which can be used to power vehicles.
Bioprocess engineer Y.H. Percival Zhang of Virginia Polytechnic Institute and State University and his colleagues focused on starch as a food source because it makes up as much as 40 percent of the human diet. (According to ScienceNOW, Zang says his Chinese background influenced his line of inquiry: "Food security has always been the No. 1 question for nearly 5,000 years of Chinese history.")
"The global demand for food could double in another 40 years owing to growth in the population and food consumption per capita," Zhang and his colleagues wrote in their article. "To meet the world's future food and sustainability needs for biofuels and renewable materials, the production of starch-rich cereals and cellulose-rich bioenergy plants must grow substantially while minimizing agriculture's environmental footprint and conserving biodiversity."
The scientists thought of turning cellulose into starch because of similarities between the compounds: both cellulose and starch are made up of glucose, although the sugar molecules are bonded together in different ways.
To convert cellulose into starch, the researchers made a "stew" of genetic material from specific species of bacteria, soil fungi and potatoes. They used these enzymes to break the cellulose down into smaller molecules, and then another set of enzymes to build these components into starch. (Got that?)
"It's a simple but nice idea," Caltech bioengineer Frances Arnold, who did not take part in the work, told Science NOW.
The process converts about a third of the cellulose into amylose. When dried, it becomes a white powder that can be add to food -- or made into biodegradable (edible?) plastics. Zhang described the taste as "slightly sweet."
The remaining 70 percent of the cellulose is turned into glucose, which can be fermented into biofuel, Zhang said.
The process is currently cost prohibitive, however. Zhang estimates that it would cost about $1 million to turn 200 kilograms of crude cellulose into 20 kilograms of starch --which would be enough to feed one person for just 80 days. But Zhang estimates that after five to 10 more years of research, the process would cost just 50 cents per person per day: "We do not see big obstacles to the commercialization of this process."
If scientists can figure out how to do it cheaply, wood potentially could provide up to 30 percent of the food that prior studies estimated will be needed to feed the world's population by 2050.
We can see it now -- pretentious restaurants and Silver Lake hipsters will be rushing to outdo each other with their all-wood menus. There will be endlessly annoying discussions about the delicate taste of birch vs. the bold flavor of oak. Twigs will be amuse bouches, and ash will be a condiment.
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