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Soy! It's no ordinary bean.

First domesticated in China more than 4,000 years ago, soybeans spread throughout Asia as they became an important food crop. They got to the United States in the mid-1700's.

Samuel Bowen was granted a patent in 1767 for inventing methods to produce soy sauce, vermicelli, and a dry powder from soybean plants he had grown. But it would be the early 1900's before commercial markets were established and soybeans were grown as a cash crop.

A pioneer in more ways than one, Henry Ford grew soybeans on farmland owned by Ford Motor Company and found ways to use the oil and meal in parts made for his automobiles.

"Now, soy products are found nearly everywhere you look-- from supermarket shelves to hog farms-even in the ink on newspapers," says Wilda Martinez, ARS associate deputy administrator for agriproducts and human nutrition sciences. "ARS researchers are developing technologies aimed at increasing markets for U.S. soybeans."

Across the nation, scientists are looking for new ways to use the soybean's oil, meal, and hulls.

Last year, researchers at the National Center for Agricultural Utilization Research (NCAUR) at Peoria, Illinois, teamed up with an Iowa technology transfer company to reduce the time it takes to identify soybeans by their fatty acid profile. ARS and MBS, Inc., in Ames, are continuing development of a calibration for near-infrared instruments to determine if soybean seeds contain high or low levels of saturated fatty acids. The profile is indicative of the quality of oil that will come from the seed.

If successful, this calibration could provide information about the fatty acid content of single soybean seeds. MBS plans to market the calibration to soybean breeders to shorten the time it takes to develop improved or specialized soybean varieties.

"With this technology, soybean breeders could potentially screen a seed in 2 minutes, compared with 6 hours for current analytical methods," says James F. Cavins, who led the project at the Peoria center. Before he retired from government service this year, Cavins said that scientists at the Peoria center analyze about 25,000 seed samples each year for soybean breeders at state universities and other public institutions.

Soy Oil--the Big Squeeze

"Extracting oil from some shipments of soybeans may be like trying to get blood from a turnip," says Gary R. List, an NCAUR chemist. "Yet, there may be no problem at all with a practically identical soybean shipment.

"It's the prior handling that makes the difference," he says. "A refining loss occurs when soybeans are handled roughly before reaching the processor."

List and colleagues have found that an enzyme called phospholipase D is the main culprit in soybean oil refining losses. It interferes with degumming--the first step in refining. [See "Enzyme Causes Soybean Oil Refining Loss," Agricultural Research, February 1991, p. 18.]

And if any product can boast that it has come a long way, it's soybean oil--used both in foods and for cooking them. Health-conscious people in the 90's are turning to soybean oil because it's cholesterol-free, low in saturated fat, and high in polyunsaturates that help lower serum cholesterol.

Today, soy oil is the most widely used cooking oil at home, in fast-food restaurants, and in prepared food products. It's used in a variety of food products including salad dressings, mayonnaise, margarine, shortening, coffee creamers, frozen dinners, beverage mixes, cookies and crackers, breakfast cereals, soups, sauces, as well as cooking oil.

This widespread use is possible thanks to more than half a century of NCAUR research on flavor preservation and storability of soybeans.

In the 1940's, most soybean oil tasted something like paint, according to retired ARS chemist Herbert J. Dutton. So he and other ARS researchers in Peoria started standardized taste tests for vegetable oils.

Picking up where her predecessors left off, food technologist Kathleen Warner has trained a 20-member panel of flavor experts, whose evaluation methods have become recognized as the quality standard for fats and oils.

Information from these sensory evaluations is ultimately used by soybean breeders to develop new varieties and validate the results of their breeding programs.

ARS and breeders at several state universities have been able to genetically manipulate the seed to produce beans with lower linolenic acid content. This unsaturated fatty acid found in vegetable oils contributes to off-flavors when exposed to air or heat.

Sensory panel tests on genetically modified soybeans have shown that potatoes fried in oil from these new soybean varieties taste better than potatoes fried in standard oils.

"The passing of 50 years hasn't made soy oil older---just better, in the sense that today its taste is neutral," says Warner. "It doesn't mask the taste and flavor of foods."

But another big problem with cooking oils is the odors they give off during high-temperature frying. Warner says linolenate-containing soybean and canola oils can produce fishy odors.

In the 1950's, researchers thought it impossible to change the linolenic acid content of soybeans by means of plant breeding.

So, for years, processors hydrogenated--that is, bubbled hydrogen gas through--soybean oil to prevent the breakdown of linolenic acid. For the most part, industry still relies on mild hydrogenation to produce cooking oils, margarines, and shortenings.

But hydrogenation adds about $200 million a year, or about a half cent per pound, to the cost of oil processing, according to Timothy L. Mounts, who is in charge of the NCAUR's Food Quality and Safety Research Unit. As an alternative, "breeders have successfully used genetic modification to lower linolenic acid to a point that off-odors are no longer a problem in some new soybean varieties,"he says.

And Peoria researchers also helped bring other important changes to the U.S. soybean industry by showing that hydrogenation could be eliminated for soybean salad oil and the oil packaged in plastic, rather than glass bottles. "Eliminating salad oil hydrogenation and switching to plastic bottles has saved industry about $310 million a year for the past 8 years," says Mounts.

Hey, There's Soy Oil in the Ink

The latest news in the soy ink story is that the pigment cartier in 100percent soy ink has been shown to biodegrade almost twice as completely as ink made of soy oil and petroleum resins, and more than four times as completely as standard petroleum-based ink. NCAUR chemists Sevim Erhan and Marvin O. Bagby conducted the degradability studies.

The research team recently completed development of black soy inks for two types of printing processes--sheet-fed and heat-set printing--having previously developed black and color inks for lithographic newspaper printing.

Sheet-fed printing is used mostly for books and can be done on either coated or uncoated paper. During the sheet-fed process, one sheet of paper is pulled through the printing press at a time. It is often used for better quality products.

The type of printing used to make glossy advertising supplements and high quality magazine pages--a heat-set process--can now be done using another of ARS' soy inks. This is one process in which soy inks haven't performed well in the past. "That's because the soybean oil does not evaporate or dry quickly in the oven used to set the ink on the paper," says Erhan.

The scientists chemically modified the oil to speed the drying process.

NCAUR first became involved with soy oil ink in 1987, when the American Newspaper Publishers Association (ANPA--now the Newspaper Association of America) asked ARS to help meet an industry goal of formulating a newspaper ink that would be stable in price, cost-competitive with petroleum-based inks, and mainly derived from a renewable resource.

Earlier ANPA efforts had already led to development of a hybrid ink containing soybean oil mixed with petroleum resins, the basic formula for which was accepted and adopted by ink manufacturers.

In less than a year of experimenting with oil and pigments, Erhan and Bagby developed a 100-percent soybean oil-based ink to be used for lithographic newspaper printing that's cost-competitive with conventional petroleum-based news inks.

Lithographic newspaper ink is a paste-type ink; ARS chemist Richard Madrigal and Bagby are now trying to make liquid soy inks for another type of newspaper printing--flexographic printing. At this time, less than 5 percent of the nation's newspapers use the flexographic process.

"An advantage our four soy-based inks (lithographic, heat-set, sheet-fed, and flexographic) will have over most other current industrial printing inks is that they don't contain petroleum solvents or other volatile organic compounds," Bagby says. "VOC's are facing more regulatory controls because of the environmental concerns of federal and state agencies."

Thus, the demand for printers to use more soy inks is greater now than ever. Many states, including Illinois and Iowa, have passed legislation requiting state printing jobs to be done exclusively with soy inks. Erhan and Bagby are confident the ARS soy ink could fill the bill for this important use of soybean oil.

If complete conversion to 100-percent soy ink occurs, about 2.5 billion pounds of soybeans-or 500 million pounds of soy oil--will be used to supply the news ink market. And other applications of the soy ink technology could lead to markets in excess of 1 billion pounds of soy oil.

Oil To Burn and To Spread

Soy oil is being studied by NCAUR scientists as an alternative to diesel fuel. "Soybean and other common vegetable oils have roughly 90 percent of the energy content of diesel," says Bagby, "and they don't have the noxious exhaust emissions of petroleum fuels. However, we hope to decrease emissions even further." But before soybean oil can replace diesel, several hurdles must be cleared.

The viscosity of soybean oil is 10 to 15 times higher than diesel fuel, which interferes with fuel injection and adds to incomplete combustion. In addition, volatilities are low, and that means that unburned fuel builds up on engine parts and in the lubricating oil.

Much of the current research related to soy oil's use as a fuel focuses on resolving low-temperature deficiencies and understanding how vegetable oils react when subjected to high temperature and pressure before burning begins. So scientists are looking for a compound that can be added to soy oil to serve as a catalyst. Ideally, it would become activated only in the combustion chamber and cause a more desirable chemical reaction, thereby improving combustion and decreasing emissions.

"There's still a way to go with our work before soy oil can be widely used as diesel fuel," says Bagby. "But if we can 'grow our own fuel' and become less dependent on nonrenewable resources, it will be worth the wait."

In the meantime, researchers are finding that soybean oil may replace petroleum and other substances used as a spreading agent, or adjuvant, when herbicides are applied to crops.

"Soybean oil mixed with certain herbicides promises to increase the effectiveness and consistency of the herbicides," says Loyd M. Wax, the agronomist who heads the ARS Crop Protection Research Unit at Urbana, Illinois. "We've had a fair amount of success against giant foxtail and selected broadleaf weeds ."

Wax and colleagues have been able to lower postemergence herbicide applications to about 5 gallons per acre-- down from the usual 10 to 20 gallons.

These field tests are patterned after successful trials by Chester G. McWhorter (retired) and other scientists in the ARS Application Technology Research Unit at Stoneville, Mississippi. Those scientists have reduced herbicide application rates to 1 gallon per acre with little to no effect on efficacy, when soybean oil is used as an adjuvant. [See "Farmer-Friendly Herbicide Applicator," Agricultural Research, February 1993, p. 11.]

Ultra-low volumes of herbicide are applied using a specially designed spraying

concept first dubbed the "T-miser." The ULV sprayer was developed by Floyd Fulgham and James Hanks, agricultural engineers at Stoneville.

Wax says differences in results from the Urbana and Stoneville field tests may be due to several factors, including different weed species, climates, and application equipment.

New Uses for Soy Protein

ARS researchers are using a variety of scientific methods including chemistry, biotechnology, and genetics to find new uses for soy protein. In fact, soy is an excellent source of protein, but it contains naturally occurring compounds that can prevent people and animals from getting the maximum benefit from it.

So makers of soy-based foods like diet shakes, baby formulas, or animal feeds must use heat or other means to deactivate the troublesome compounds, known as trypsin inhibitors. There are two basic types of these inhibitors: Kunitz and Bowman-Birk, named for researchers Moses Kunitz and Donald E. Bowman and Yehudith Birk.

But heating is costly, says David J. Sessa, an ARS chemist at Peoria. New techniques for processing soy meal could cut the high energy costs, as well as add to soy's value in world markets.

Sessa has developed a pure protein model system to demonstrate to industry how heat affects the whole soybean.

"Once we know precisely how much heat is needed, we can alter proteins and design them with specific functional properties," Sessa says. "These newly modified proteins could then be incorporated into new foods, feeds, or industrial products."

In earlier studies, Sessa inactivated trypsin inhibitors by treating soy with sodium metabisulfite, a food additive used in small amounts in processing frozen french fries and in winemaking.

"It's an inexpensive way to inactivate the trypsin inhibitors," he says.

In 1990, Sessa conducted a study with Chhorn E. Lim, a biologist in the ARS Tropical Aquaculture Research Unit at Oahu, Hawaii. They fed shrimp diets containing soymeal in place of some protein that would otherwise have come from fishmeal or other marine animal sources.

The study was the first to demonstrate that marine shrimp probably aren't as sensitive as other aquatic species to soy trypsin inhibitors.

What, No Trypsin Inhibitors?

Developing soybean varieties lacking some or all trypsin inhibitors is another approach to overcoming the processing problems caused by the compounds. ARS and University of Illinois scientists have pinpointed plants that may lead to a futuristic variety that would be nearly free of the unwanted inhibitors.

And they now have tools to screen soybeans for both the Bowman-Birk and Kunitz inhibitors. Specially designed proteins--monoclonal antibody probes--seek out and bind to the inhibitors, enabling researchers to detect them.

Each probe specifically binds to one particular inhibitor. ARS researchers David L. Brandon, Anne H. Bates, and colleagues developed the probes in their laboratory at the ARS Western Regional Research Center, Albany, California.

Using the probes, Theodore Hymowitz, a geneticist at the University of Illinois, Urbana, recently screened more than 13,000 soybeans and discovered that some wild relatives of domesticated soybeans apparently have significantly lower amounts of the Bowman-Birk inhibitor.

Earlier work targeting the Kunitz inhibitor resulted in a soybean variety dubbed "Kunitz" being offered to farmers in 1991.

A hardy soybean with only a trace of the Kunitz-type inhibitors, it was developed by Hymowitz, Richard L. Bernard, now retired from ARS, and Charles R. Cremeens, who is with ARS at Urbana.

Hymowitz envisions that it may be possible within the next 10 years or so to combine the low Bowman-Birk wild plants with the Kunitz variety to yield a ultralow-trypsin-inhibitor soybean.

And until then, the low-Kunitz bean offers an environmental advantage: Though it still contains the Bowman-Birk inhibitors, it requires less energy to inactivate them.

When steam-heated for 20 minutes at about 250 degrees F, flour from a standard commercial variety still had 20 percent of its inhibitors left, reports Mendel Friedman of the ARS team at Albany. But flour from the low-Kunitz beans had near-zero levels of active inhibitors.

Transforming Soy Proteins

ARS researchers at several locations are hoping to expand markets for soybeans by looking at new ways to use soy protein in foods, feeds, and industrial products.

Unfortunately, nature puts proteins together in a way that's not always suitable for modem food technology.

At NCAUR, scientists are looking at the molecular composition of important soy proteins and studying the effects of chemical, mechanical, and heat processing on these proteins.

"If we change the proteins' physical forms, we can enlarge the range of options for using heated proteins in many food and industrial applications," says chemist Walter J. Wolf.

One of the major obstacles to using soy protein in food products is its solubility. Wolf is tackling the problem by attaching monosaccharides--such as glucose--to glycinin, the major storage protein of soy.

"If we can make soy proteins more soluble in acidic environments, it may be possible to develop carbonated soft drinks that are protein enriched," says John A. Rothfus, a chemist and also leader of the project.

"Proteins can do many things that starch and gum can't do, especially when processing and developing products with special characteristics, such as moisture resistance," says ARS chemist Frederick F. Shih at the Southern Regional Research Center in New Orleans, Louisiana.

Shih has found a way to make plastic films and coatings from soy proteins. The films and coatings can be made into moisture-resistant food packaging materials.

Controlling the genetics of the soybean plant may also change the composition of its proteins, allowing them to be more easily used in additional food products.

Niels Nielsen, an ARS geneticist at Purdue University, is using genetics to make better soybean curd, or tofu, a staple in the Asian diet that seems to be increasingly popular with diet-conscious Americans.

Tofu is a high-protein product made from soybeans grown for food uses. Whitish in color, it has a very bland flavor, a consistency similar to firm custard, and a versatility that allows it to be prepared in many ways.

"The problem is that not all soybeans make good tofu," says Nielsen. "And with the surging popularity of tofu, there is a need for beans tailored for just that use."

Some soybeans, particularly those slightly low in protein, make tofu that is too soft and fragile--prone to mechanical damage during handling.

Other soybeans give tofu undesirable tastes and aromas that can be described as grassy, beany, buttery, or astringent. Still other beans produce curd that is pale yellow in color instead of the white preferred by many Asians; because soy milk and tofu turn yellow as they age, the off-color is undesirable.

Nielsen's goal is to make tofu a more attractive source of protein by eliminating lipoxygenases, the enzymes that produce the beany off-flavor sometimes associated with tofu.

"Evaluations by trained taste panels have shown that the beany flavor is reduced by eliminating one or more forms of the enzyme from the soybean seeds," he says.

The improved flavor trait was found in very "unadapted" soybean lines--in this case, ones with green and black beans. Now, the genes for improved flavor have been bred into a soybean variety with good agronomic qualities.

"The result is a better tasting soybean that also has improved agronomic traits," says Nielsen. "Although products made from these beans have the undesirable pale-yellow color, the germplasm from this line will be very useful in further breeding programs."

A small-scale tofu production line has been set up in Nielsen's laboratory to help quality-test tofu and soy milk from various soybeans. However, the scientists are encouraging commodity organizations to assume responsibility for performing this service for plant breeders.

Patents protecting the low-lipoxygenase traits are in force both in the United States and Japan.

Improving Soy's Digestibility

Humans and animals often have problems digesting some forms of soy. Using the tools of biotechnology, NCAUR chemist Tsung Min Kuo is trying to make soy products easier to digest.

"Soybeans produce a class of complex carbohydrates known as raffinose sugars that are largely indigestible by humans and animals," says Kuo. "These sugars decrease feed efficiency in farm animals that are fed more than 90 percent of domestic soybean meal. In humans, they produce gastrointestinal effects that discourage soybean consumption."

In 1988, University of Minnesota scientists found that removing these sugars increased the amount of metabolizable energy derived from the soymeal in the feed. So Kuo decided to search for soybean seed naturally low in raffinose sugars. More than 1,000 seeds from the ARS Soybean Germplasm Collection and from breeders have been screened.

Now, Kuo and his colleagues are also at work genetically modifying soybeans to reduce raffinose sugars.

"We have isolated a small section of a gene that codes for an enzyme called galactinol synthase that is needed for the production of raffinose sugars," Kuo says.

The researchers are continuing studies on other soybean enzymes that could perhaps be modified so as to inhibit raffinose sugar production. One of the techniques they use is antisense--a relatively new biotechnological tool that tricks a gene into not doing what it's programmed to do.

In this case, the objective is to try to block the genes responsible for making the enzymes needed to produce raffinose sugars.

Having access to processed products with little or no raffinose sugars would significantly spur consumer interest in soybeans.

But several foods developed years ago from soy protein combined with other commodities have already contributed greatly to improving world nutrition. Corn-Soy-Milk (CSM) is just one example of a high-protein, soy-based blended food product developed at NCAUR that has enjoyed extended use overseas.--By Marcie Gerrietts, formerly with ARS, Linda Cooke, and Marda Wood, ARS.

To contact scientists mentioned in this article, write or telephone Ben Hardin, USDA-ARS-NCAUR, 1815 N. University St., Peoria, IL 61604; phone (309) 681-6597, fax (309) 681-6690.
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Title Annotation:part 2
Author:Gerrietts, Marcie; Cooke, Linda; Wood, Marcia
Publication:Agricultural Research
Date:Nov 1, 1993
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