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Adding value to alfalfa

New processes extract high-dollar products from the practical legume.

The green alfalfa juice Richard Koegel concocts in his laboratory at the USDA's Dairy Forage Research Center in Madison, WI, isn't some high-protein health drink, although it would probably be a fairly healthful, if not tasty, beverage.

Rather, this liquid and the fiber from which it is pressed contain a variety of valuable substances waiting to be distilled out, including lactic acid, protein concentrates and enzymes, worth the equivalent of $1,000 to $2,000/acre of crop.

Alfalfa has such good agronomic characteristics that it is logical to try to add more value to it, Koegel says. "It's a perennial, so you don't have to reestablish it each year, it fixes its own nitrogen, and its deep root system makes it more hardy to weather variations and has good long-term effects on the soil. It fits well in rotation with cash crops to break disease and pest cycles, and, of course, there are the soil conservation benefits."

He adds that other crops may be easier to modify genetically, such as tobacco and potatoes, but they don't offer the overall agronomic benefits of alfalfa.

Lactic acid from legumes. One of the most promising derivatives from alfalfa is lactic acid, a syrupy liquid formed by fermenting sugars, which can be made "organically" by enzyme treatment of crops such as alfalfa and corn or synthetically with chemicals. It is commonly used as a food additive to enhance flavor and increase shelf life.

But a new use for lactic acid is in the production of biodegradable plastics. A new process developed through a joint venture of Cargill and Dow Chemical has made the production of biodegradable plastic much more cost-efficient and flexible, allowing for the manufacture of such products as clothing fibers, clear film and food containers, along with the already common garbage bags and mulching film (see "Golden fields of plastic," February 2000).

Although the current Cargill/Dow process uses corn as its lactic acid source, alfalfa could be used as the base fiber, Koegel explains. The USDA-ARS agricultural engineer has devised a method of extracting the lactic acid by pretreating the alfalfa fiber for 2 min. in extremely hot water while applying 150 lbs./sq. in. of pressure. Then by adding some hydrolytic enzymes and special bacteria, he can get lactic acid yields as high as 60%. Koegel hopes to further refine the process to reduce costs and improve his yields.

The current U.S. market for lactic acid is about 50,000 tons, and half of that is imported. With the potential to supply more of that need from alfalfa and to further expand the lactic acid market through new applications such as in the production of biodegradable plastics, the market for alfalfa could expand significantly in the coming years.

Extracting enzymes. Another growth area for alfalfa involves genetically engineering varieties to produce enzymes, which are proteins that control biological reactions. These types of enzymes are currently used in a variety of products, including animal feeds and laundry detergents. Researchers predict that the market for this industrial enzyme will double in the next decade.

Plant biotechnologists at the University of Wisconsin Biotechnology Center have successfully engineered alfalfa to produce high levels of the enzyme phytase, which is used in poultry and swine feeds. Koegel and colleague Richard Straub have developed the process for extracting the phytase from the alfalfa plant. The result, again, is a potent juice that contains protein, enzyme and xanthophyll, all of which are valuable in poultry feed. "Once concentrated, the liquid can be sprayed on dry feed or dehydrated and incorporated dry," Koegel explains.

Only 1 to 2% of the crop is actually used in the enzyme-making process, but the leftover high-fiber by-product can be fed in cattle rations. The per-acre value of the phytase alone is between $500 and $1,000, Koegel says. But that doesn't include processing costs.

He estimates that 250,000 acres of the genetically altered alfalfa would be enough to meet current market needs for the enzyme. So although the crop return looks good, the amount needed is limited.

Currently, licensing of the genetic materials and transformation processes is holding up marketing of the phytase-producing crops. "Once that gets settled, things could move along fairly quickly," Koegel says.

In fact, one entrepreneur says he and a group of private investors could have an alfalfa wet fractionation (processing) pilot plant up and running in southern Minnesota as early as next summer. Although he declined to provide more details at this time, he said the technology is there and such a venture "looks very promising."

Beyond feed. But the possibilities for alfalfa use don't stop there. The crop also can be genetically altered to produce enzymes that would offer environmentally friendly options for the paper industry, as well as help break down oil in cases of petroleum spills.

And in the rapidly growing field of nutraceuticals, researchers say that alfalfa could be genetically modified to contain vaccines and later fed to livestock, providing more natural protection from disease. Research is also under way to explore the possibility of using this forage crop to grow insulin for human use, because studies have shown that alfalfa extracts have activities affecting insulin and the pancreas.

If any of these developments can help turn alfalfa into a high-value crop worth more than just its use as livestock feed, this lowly legume may not be so lowly after all.

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