Back in early February I got an email from a reader searching for ethanol producers that want to sell fusel oil. He was contacting me on behalf of a trading company located in Saigon, Vietnam, that purchases agricultural products, including fusel oil, and resells them to international buyers that use it as in ingredient in soaps, pesticide or animal feeds. The company purchases some from China and some from an ethanol plant in Vietnam that produces ethanol from tapioca but would like to purchase more. The reader wondered if I knew of any U.S. ethanol producers that sold fusel oil or would sell it. The company’s minimum purchase amount is 24,000 liters (more is better) and pays about $600 metric ton for the fusel oil it purchases from China.

I was totally stumped. A search of our website turned up only two articles that referenced fusel oil, one an article written for our magazine by an outside company and the second one a press release that mentioned fusel oil only briefly. I wasn’t even sure who could answer his question. Sometimes the answer to a question simply is, I’m sorry, I just don’t know. But I was intrigued and wanted to learn more myself. I wanted to know what ethanol producers do with fusel oils now and if it is a potential new coproduct of ethanol production. So I decided to dig for answers.

I spent the last several months emailing various sources. I hit a few dead ends but eventually I got what I was looking for from Sabrina Trupia, assistant director of biological research at the National Corn-To-Ethanol Research Center, and Neal Jakel, former general manager at Illinois River Energy LLC now with Fluid Quip Process Technologies.

Trupia explained that fusel oils are higher alcohols (amyl/iso-amyl and n-propyl alcohol) formed under less-than ideal conditions during ethanol fermentation. For example, the pH may be too low or the temperature too high. “They are denser than ethanol so they appear at the end of distillation and look oily,” she said, adding that they are used in the beverage and perfume industries.

Currently, ethanol producers work to keep fusel oil production to a minimum, to keep the plant running smoothly. “They are typically produced and run in the 100 to 150 ppm concentrations range within fermentation, so low amounts over all,” Jakel said. “Above 200 ppm, fusels will become toxic to the yeast and stop fermentation.”

There have been various inquires, through the years, about selling fusel oils but Jakel doesn’t know of any ethanol producers that are doing that. Ethanol producers remove fusel oils within the rectifier column and add them back into the 190 proof ethanol, meaning it ultimately ends up in the 200 proof final product, he said. Technically it would be possible to sell fusel oils as a separate product but factors to consider are the market-size potential and purification cost to separate the alcohols.

So there you have it. That’s what I know about fusel oil. If you have more information on this topic or are interested in contacting this Vietnam-based company, please email me at hjessen@bbiinternational.com.