Normal soybean seeds contain at least three lipoxygenase isozymes, called L-1, L-2, and L-3. These isozymes are responsible for the generation of objectionable grassy beany and green flavors which build a barrier against the wide utilization of soy protein products. Recently, the three types of mutants lacking L-1 (Hildebrand and Hymowitz, 1981), L-2 (Kitamura, 1984), and L-3 (Kitamura et al., 1983), respectively, were found.