Chapter Ten - Soybean secondary metabolites and flavors: The art of compromise among climate, natural enemies, and human culture.

Soybean is a food crop in high demand in Northeast Asia. Besides protein and oil, soybean is also a rich source of health-beneficial secondary metabolites such as flavonoids, terpenes, and alkaloids. The long history of soybean domestication resulted in a rich collection of soybean germplasms, which could be generally categorized as wild, landrace, and cultivated soybeans. Previous research has shown that soybean seeds from diverse genetic backgrounds exhibited different metabolite profiles. Germplasms originating from different geographical regions, i.e., at different latitudes and longitudes, probably experienced different selective pressures and evolved different secondary metabolite profiles. Domestication has generally led to a reduction in secondary metabolite contents in seeds since many of these compounds are related to the bitter taste or other agronomic traits that may hinder the ease of farming and harvest. These selection forces have possibly rendered the different flavors of soybean germplasms. Due to the popularity of soy food products, the post-domestication selection of soybean based on flavor is a common phenomenon. In Northeast Asian countries, soy foods such as soy milk, tofu, and fermented soy products are popular. Based on the consumer preference for the flavors of these products, soybean germplasms with different metabolite profiles are selected for different commercial uses. However, the breeding of soybeans for maximizing health benefits and for the preferred flavors of food products may create contradictions. Industrial methods to remove undesirable flavors and molecular breeding to produce cultivars with desired metabolite profiles may be the solution. [ABSTRACT FROM AUTHOR]