The fact that only the starch portion of the corn kernel is used for ethanol production is so well understand by the industry yet so unknown outside its circles. If the role of distillers grain – the ethanol co-product containing all the “food” parts of the kernel – was better understood, it might change the conversation surrounding corn as food and fuel.
Another conversation-changer may be fractionation, an old food-milling technology now being applied in the ethanol industry. Using fractionation to separate the corn kernel into its main components gives ethanol production a boost of efficiency by better isolating the starch and gives the industry access to the added value of new revenue streams – many in the food sector.
The anatomy of a corn kernel
Those small, golden kernels are comprised of many valuable parts. The three main components of the kernel are the bran, endosperm, and germ.
The bran holds the corn’s fiber, the hard outer layer of the kernel. The endosperm contains the majority of the corn’s starch, found on the interior of the kernel. The germ is at the center of the kernel by the bottom tip cap, containing an abundance of proteins and oils.
A corn kernel contains about 75 percent starch, 9 percent protein, 9 percent fiber, 4 percent oil, plus small amounts of ash and sugars.
Though a small portion of the bran is convertible to simple sugars that can be utilized by the yeast, the starch is really the only viable fermentable part of the kernel. In a standard dry-mill ethanol plant, the corn is run through a hammer mill and the ground corn is sent through the fermentation process. Because the other components of the corn – proteins, oils, fiber – are not fermentable, they are not able to be converted into ethanol and instead come through the process in the distillers grain co-product.
But adding fractionation to the ethanol process changes this by splitting the corn kernel into its main components at the outset. This increases the efficiency of fermentation by allowing the starch to do what it does best, and it opens the door to new revenue streams by making the proteins, oils, and fiber available for new and other proven uses.
How and why fractionation works
Fractionation is an old technology being applied in a new industry, notes Neal Jakel, Fractionation Program Manager for Delta-T Corp. The process has been used for more than 100 years by milling operations to separate grain for use in various food products.
“Fractionation is really about adding more value,” Jakel said, calling it a natural progression in an industry that first sought to add value to corn. Ethanol has been the first logical step, and fractionation can continue this natural progression of value-added.
Fractionation can be built in to any new ethanol plant or added to the front end of any existing ethanol plant.
Incoming corn is separated into its main components by either mechanical or abrasion milling equipment. A degerminator is typically used, which forces the whole kernel against a screen, pushing the germ portion through but retaining the endosperm. The endosperm and bran are then further separated, and now with the bran, germ, and endosperm isolated, these streams are ready for their respective processing.
Isolating the starch – the main fermentable part of the corn kernel – boosts the efficiency of the ethanol production process. With less non-fermentable material going through the process, energy demand is down. Jakel says there can be a 15 to 20 percent reduction in material to dry at the back end of the process, which leads to significant energy savings. Less drying may also lead to lower emissions from the ethanol plant.
In addition, the higher concentration of starch in the stream leads to more efficient distillation. A purer starch stream may need fewer enzymes for fermentation and require less energy to separate the ethanol from the beer. The cleaner starch stream may experience less fouling, which means reduced chemical usage for cleaning.
“These are little things that all add up to the ethanol plant running smoother, stronger, longer,” Jakel said.
With its DST™ or Dry Separation Technology system, Delta-T guarantees a 6,000 Btu-per-gallon reduction in energy use at the ethanol plant.
MOR Technology, a technology services company based in Metropolis, Illinois, has developed a fractionation system they say combines the best of wet and dry milling technology, and is designed as a GMP food-grade facility, allowing ethanol producers to capture the added value of food-grade products.
The company says its MOR-Frac™ Plus+ Milling System adds the step of soaking the corn’s germ, which increases the germ’s oil content from 18 to 24 percent up to 40 or 45 percent oil. This soak solution – full of inherent starches, sugars, and nutrients – is sent back to fermentation, which reduces overall starch loss and increases fermentation yield.
“Fractionation is a risk-management program for the ethanol plant,” Jakel said, emphasizing how the increased efficiency and new value-added products can help producers boost the bottom line. He believes having a fractionation system in place can reduce operating costs by 8 to 15 cents per gallon, which means a world of difference in a tight-margin situation.
MOR Technology analyzed the potential use of its system on a 55 mgy ethanol plant and found an estimated million in net income over a year’s time, or 28 cents per gallon. These numbers show a producer’s break-even point going from $3.70 a bushel of corn to close to $5.00 a bushel.
New opportunities beyond the starch
Now with access to the corn kernel’s other components, the door opens to creating new products at the ethanol plant.
The fiber in the corn’s bran, for example, has multiple applications. It can be used as a cattle feed, ideally suited for the beef and dairy market. The removal of the fiber from the starch stream that goes to ethanol also changes the composition of the existing distillers grain, making it a higher-protein feed. Experts say the protein-enhanced DDGS will be more welcome in the swine and poultry feed markets at a much higher value.
The fiber from a fractionation ethanol plant can also be used as an additive in human food. It contains oils such as phytosterols, which are known to lower cholesterol. From an ethanol plant, the fiber can be marketed to specialty processing plants that can utilize these high-value components.
In addition to its use as a food additive, the bran can be used as a feedstock for cellulosic ethanol. Bran is made up mostly of cellulosic material that is readily converted into simple sugars, the key ingredient for the fermentation process. With the bran separated at the front end of the process, a dedicated conversion and fermentation system could be put in place to produce cellulosic ethanol – another added-value aspect for ethanol producers.
And under the right circumstances, the fiber can be burned in a biomass boiler system to provide power to the ethanol plant, reducing fossil fuel consumption. Bran typically contains about 7,000 Btus per pound, which when used as a power source for the process, could lead to a 12 to 15 percent reduction in energy use at an ethanol plant.
The corn’s germ is a very valuable portion of the kernel, containing an abundance of proteins and oils. The oil in the germ can be extracted for use in other industrial processes – such as the production of biodiesel – or for use as a human food ingredient. Jakel notes that corn oil is highly sought after in today’s market due to health concerns over the trans fats in other oils.
De-oiled corn germ can be used itself for animal feed or mixed with the bran and the syrup from ethanol production to create a form of corn gluten feed, similar to that produced at a corn wet mill. Jakel notes that the germ is loaded with key amino acids like lysine that are ideally suited for animal feed markets.
Ethanol producer POET’s fractionation process, trademarked Bfrac™, uses the fiber and germ to create new value-added co-products Dakota Gold HP™, Dakota Bran™ Cake, corn germ meal, and corn oil.
While many other systems have to send the germ on to another facility for the corn oil to be extracted, MOR Supercritical, a division of MOR Technology, makes on-site corn oil extraction possible. Most oil extraction methods today use hexane solvents, and although hexane is an abundant and affordable byproduct of petroleum refining, it is also a toxic, flammable, and carcinogenic chemical. Instead of hexane, MOR’s process uses supercritical fluids such as carbon dioxide to extract the corn oil from the germ. The resulting corn oil is high quality and all natural.
Fractionation means food and fuel
As MOR Technology notes on its website, fractionation addresses the “food vs. fuel” debate by preserving the corn’s valuable components and routing them back into the food chain.
ICM, Inc. has also promoted its fractionation system, calling it a “food and fuel technology bundle.” ICM’s dry fractionation is only the first of a six-step system, which also includes solid fuel combustion, germ oil extraction, protein extraction from germ, single-cell protein feed from syrup, and ethanol from fiber (cellulosic ethanol).
“The integration of all six solutions will help end the current food vs. fuel debate,” ICM’s website notes, “with a business model that can help feed the world.”
ICM put its food-and-fuel plan into action when it partnered with Lifeline Foods in February 2006 to add ethanol production to the St. Joseph, Missouri manufacturer of corn-based food ingredients. ICM has a 49 percent stake in Lifeline Foods, with 51 percent owned by AgraMarke Quality Grains, a cooperative of now more than 600 farmers from Missouri, Kansas, Iowa, and Nebraska.
The St. Joe plant is now able to take in the bushels of corn provided by its farmer-owners and turn them into 50 million gallons of ethanol annually, plus a wide variety of corn-based ingredients.
Lifeline makes several dry corn milled products: flaking grit for corn flakes, brewers grit for the brewing industry, snack meal for processed foods, corn meal for breads and muffins, and corn flour for pancake mixes and ready-to-eat cereals.
The plant also creates masa flour products – tortilla flour, chip flour for tortilla chips, and taco flour – as well as corn-based food and industrial binders. The corn’s bran, made possible through the fractionation process, is available as a food ingredient that adds fiber to baked goods and snacks.
“Fractionation is the first step to diversify the base ethanol plant beyond just ethanol and DDGS,” Jakel said. “It is the lynchpin to going forward to a biorefinery.”
It seems the young ethanol industry has only touched on a fraction of its potential.
