Chapter 8: Soybeans
Published:16 Dec 2010
For most of their 300 year domesticated history soybeans have been grown to feed humans and animals. In the last decade there has been increasing use of soybean oil (which constitutes about 20% of the seed) for energy, in the form of methyl ester biodiesel. Soybean biodiesel, while more expensive to produce than petroleum diesel, offers a number of advantages over all petrochemical fuels, including increased fuel performance, lower carbon emissions and biodegradability. Soybean biodiesel use is limited by the functional properties of soybean oil, cost and oil supply. The oxidative instability of soybean oil will compromise ignition performance. Saturated fatty acids reduce the cold flow properties of soybean biodiesel and limit its use in cold environments. High oleic, low palmitic acid soybean oil addresses these functional limitations. Efforts by plant breeders over a 30 year period has resulted in high oleic, low palmitic acid soybean lines but they have not been commercialized due to the breeding challenges associated with pyramiding multigenic factors, required for full penetration of the target trait and the observed instability of the phenotype across environments, as well as poor agronomic performance of the crop. On the other hand, using the tools of biotechnology, single locus, environmentally stable, high oleic, low palmitic acid soybean lines have been produced in high performing elite varieties. These varieties are being commercialized by major seed companies. The methyl ester biodiesel from these lines has improved functional properties including cold flow characteristics similar to petroleum diesel. Future biotechnology efforts will be directed towards improving the oil yield of the soybean crop.