Delicious Inspiration

Thanksgiving table offers ideas for new drying agents
By Kris Bevill | October 18, 2011

Inspiration can come from anything at any time, even the Thanksgiving dinner table. A few years ago, Michael Ladisch, a distinguished professor of agricultural and biological engineering at Purdue University, was at his mother-in-law’s for Thanksgiving when a triangular-shaped bag of ingredients usually reserved for pudding caught his eye. “I saw this bag of tapioca pearls on the counter, looked at the contents and it turned out to be starch,” he says. “It led me to wonder whether these materials, which look a little like molecular sieves, would work for drying ethanol.”

In his role as a professor at Purdue, and as chief technology officer at cellulosic ethanol developer Mascoma Corp., Ladisch is very interested in various starch properties and how they could be used in industrial applications. With funding from Archer Daniels Midland Co. and assistance from ADM researcher Ahmad Hilaly, Ladisch and fellow Purdue researcher Youngmi Kim characterized varying sizes of tapioca pearls and found that Ladisch’s initial speculation was correct—the pearls were excellent at absorbing water from fuel-grade ethanol. In fact, the tapioca collected about 34 percent more water than corn grits, which is another natural alternative to nonrenewable molecular sieves. Some ethanol facilities use corn grits packed into towers to absorb water from ethanol, but those grits are irregularly shaped and contain fiber, protein and other unnecessary substances. Tapioca pearls are a spherical structure and are comprised of 100 percent starch. They can be dried and reused and have the potential to become feedstock for ethanol when they are no longer useful as drying agents. “Tapioca is very efficient and it’s all natural,” Ladisch says. “There are no disposal issues. It’s much more environmentally friendly.”

Tapioca is derived from the cassava plant, which is grown mostly outside of the United States. While tapioca is readily available in North America, Ladisch believes South American facilities would be the most likely to use it. Ladisch’s starch-based research is a continuing effort at Purdue, and he believes there could be other products like tapioca that could also be used to replace molecular sieves. “It’s a fundamental research area, but it’s still very fascinating,” he says. “Now that we understand how they work, we could make them from other forms of starch.” 

—Kris Bevill