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Grown to taste

The tastiest tofu in Taiwan could soon be coming from Minnesota.

Soybean varieties developed from Japanese and Chinese stock and adapted to grow in Minnesota are finding their way to the export market. AURI is supporting lab and field tests of new food-grade varieties to help put more Minnesota beans on the export track, says Keith Sannes, deputy director of commercial development.

Researchers at the University of Minnesota and North Dakota State University are examining plant yield and disease resistance to determine the best growing traits for Minnesota. They are also studying soy varieties to find the best qualities for tofu, soy milk and other products for Asian markets, says Jim Orf, U of M professor of agronomy and plant genetics. For several years, Orf and other researchers have crossed soybeans from Japan and China with U.S. varieties, trying to blend the characteristics desirable for food – flavor and protein – with traits such as high yield, adaptability and disease resistance.

Soy big biz

Soybeans and soy products make up the largest portion – 33 percent – of Minnesota’s agricultural exports, according to the Minnesota Trade Office. Minnesota is the fourth-largest soybean producing state, exporting $727.6 million worth of soybeans and products in 2000. Most are produced for animal feed and oil; food-grade soybeans comprise a small part of the market and are often grown on plots of 5 to 40 acres – but they sell for a higher price.

With AURI’s support, Orf is growing more than 40 lines of food-grade soybeans for testing by Sam Chang, professor of cereals and food science at NDSU.

Tofu tests

From Orf’s samples, Chang and his assistant take a few pounds of beans, soak them, grind them and separate the soybean residue from the milk. After the soy milk has cooked for 10 minutes, a coagulant is added and the milk is transferred to a mold and pressed with weights for 30 minutes. Cooled and removed from the mold, the tofu is analyzed for chemical content and sensory qualities.

A self-professed tofu connoisseur, Chang looks at processing yield – grams of final product per 100 grams of soybeans – color, protein content and texture. He never tires of taste-testing the end results. “We grew up with it. I think tofu is a health food. É We conducted research to show tofu has antioxidant characteristics.” Machines can do some of the analytical work, Chang says, “but people can judge if the texture is smooth or not. For good tofu, smoothness and firmness are desirable, but not too soft, not too firm.”

A test of time

Following an initial plant breeding, Orf says, several years of inbreeding and yield testing are needed to develop a commercial soybean variety. “You weed down from thousands of lines to 20 to 40, then three to four that companies may be interested in. In the end, if you have one or two, you feel pretty good.” With yield testing, growing several generations might take up to nine years.

A few varieties are now available for Minnesota growers, Orf says, including Proto and Toyopro. “Some are adapted to northern Minnesota, and some to southern Minnesota. There’s a 100-mile band across the state where (a given variety) is best adapted.”

Processors and marketers want to know which varieties will make the most attractive exports, Sannes says. The tests done by Orf and Chang will help processors “know which varieties make good tofu,” Sannes says. “Some might yield differently – quality and yield are variety-dependent.” Processors can then contract with growers for specific varieties.

“(Food-grade) soy commands a premium,” Chang says. “Oilseeds do not generate a lot of income. É The potential for the farmers or traders to market a more valuable crop is high.”

Chang adds that his lab does soybean analysis for individual growers or groups. “With the health benefits of soybeans, it’s very meaningful research.”

The effect of storage

Chang has also studied how storage affects soybean quality. He calls the results “very important” for growers who store beans on the farm. In Minnesota’s heat and humidity, Chang says, soybean quality can be reduced. Tangible effects include reduced solubility and flavor, lower product yield, and overall deterioration in tofu quality.

Information from the soybean trials is being shared with the Minnesota Department of Trade and Economic Development, Minnesota Soybean Growers Association, Minnesota Soybean Research and Promotion Council and the Minnesota Department of Agriculture, Sannes says. The Minnesota Crop Improvement Association will license the new varieties. Depending on demand, varieties may be licensed to one or two seed companies, to a half-dozen companies, or to any company as a general release.

Want to know more?

For information about food-grade soybeans in Minnesota, contact the following:

Seed directory

Minnesota Crop Improvement Association, 800-510-6242,

Performance data

University of Minnesota,

Food analysis

Sam Chang, NDSU, (701) 231-7485,

All aspects

Minnesota Soybean Growers Association and the Minnesota Soybean Research and Promotion Council,