‘Every Molecule Matters’: Corn Kernel Fiber (CKF)

by Lisa Gibson (Ethanol Producer Magazine) The steps are simple, with low capital and strong ROI: Engage with the appropriate analytics labs to help calculate in-situ cellulosic ethanol production from corn kernel fiber; register those gallons with the appropriate markets; and enjoy the new competitive advantage. McCord Pankonen, ethanol and biodiesel service director with EcoEngineers, says in-situ CKF ethanol is seeing a surge as a result of its accessibility and its advantages over first-generation ethanol in programs such as the Renewable Fuel Standard and California’s Low Carbon Fuel Standard.

“What’s neat about the opportunity is ethanol producers really don’t have to do a ton of altering of their plants,” Pankonen says. “It increases revenue for the same kernel that’s going through the process, so really the lift is to get it registered and then engage markets.”

Pankonen also strongly recommends ethanol producers looking into CKF ethanol (also called generation 1.5) partner with the right enzyme provider to maximize value in fiber-degrading packages and strengthen cellulosic production. EcoEngineers, for its part, helps consult, advise, audit programs and train plant staff across a wide area of opportunities, including adherence to cellulosic compliance standards in the RFS and LCFS.

Certainly, the process to register and continue compliance is complicated, but producers can see significant benefits through the work, he says.

“When we’re in a market calculating carbon intensity, every molecule matters.”

Enzymes: Maximizing Markets
“One of the first decisions an ethanol producer needs to make is whether they want to maximize the value of their corn kernel fiber or just enter the cellulosic ethanol market,” says Laura Bostic, global marketing manager with Novonesis.

“Is the focus generating D3 RINs, participating in state markets like CARB (California Air Resources Board), increasing ethanol and oil yield, or a combination of other drivers? Essentially, what is the customer hoping to achieve?” she adds.

Fiberex products contain powerful cellulases to generate cellulosic ethanol for D3 RINs or state low-carbon markets, Bostic says. “Hemicellulases work to further break down and hydrolyze the fiber matrix, releasing trapped cellulose, starch and oil. Meaning, in addition to cellulosic ethanol, more glucose is released, giving a bump to starch ethanol, plus a significant increase in extractable oil potential.”

Fiber-degrading enzymes have more complex work to do than a traditional first-generation starch enzyme. Traditional first-generation glucoamylases and proteases do not degrade cellulose or hemicellulose—the main components of corn kernel fiber, Bostic explains. So when a cellulase or hemicellulase is used to break those down, they’re also hydrolyzing the fiber into fermentable sugars the yeast can convert into ethanol.

IFF Staff Scientist Brad Kelemen emphasizes fiber’s complexity as well. “Cellulose is really tough. It’s a recalcitrant substrate so it’s highly insoluble. It’s problematic and requires chemical pretreatment or other treatment to get access to cellulose.” It’s much tougher, he says, than the starch part of the process in terms of the speed of the reaction and the challenges working with it. “The hemicellulose—the fiber—is difficult in that it’s complex. There’s a lot of variety in it and there’s a lot of branching, a lot of cross linking, a lot of different bonds to work on.”

IFF focuses on dual purposes for its enzyme packages, seeking to maximize the value of other CKF coproducts such as corn oil and other benefits such as cellulosic RINs and LCFS qualification, Kelemen says.

Testing and Analytics
Neogen has captured interest in the ethanol industry for its work on the in-situ cellulosic ethanol testing and quantifying method that was approved by the EPA in March 2024.

The ASTM approval process, required for EPA approval, is robust, Nichols (Matthew Nichols, director of biofuels strategic market for Neogen) says. It requires full publishing of the method and unanimous approval by voting members. After several iterations with the ASTM process, the testing method was approved by the EPA and prompted an influx of EPA Efficient Producer Pathway approvals. As of April 2024, a total of 14 ethanol-related operations had approved D3 RIN pathways, according to the EPA. As of April 2025, that number had increased to 117. Not all of these approved D3 RIN pathways, of course, are for CKF.

Nichols points out that the accomplishment was the result of industry-wide collaboration, with input from producers as well as top CKF analytics labs. “The industry came together and worked through some scientific inquiry; we did meet the requirements and we got the method across the finish line, so it has met the EPA specifications and we’re just really happy about everyone working together.”

The National Corn-to-Ethanol Research Center of Southern Illinois University Edwardsville also has created an in-situ CKF ethanol testing method, though it is not approved for RFS pathways or for California’s LCFS. Yanhong Zhang, interim executive director of NCERC, says it is a VCSB method, but the lab has not sought EPA approval.

“In my opinion, the reason NCERC’s method was not popular among the industry ... was because our method only delivers results to support about 1% ethanol increase for 1.5-generation processing versus some other popular methods will deliver results to support over 3% ethanol increase (for the same fermentation batch),” Zhang says. READ MORE