Saponin composition complexities in hypocotyls and cotyledons of nine soybean varieties

Soyasaponins can be classified into two groups as A saponins and DDMP saponins. Fully-acetylated group A saponins, located on the seed hypocotyls, are the major cause of undesirable characteristics in soy foods. Apart from the fully-acetylated and deacetylated group A saponins, other saponin components have not been studied. This research aimed to identify 105 saponins in the seed hypocotyls and cotyledons of nine saponin phenotype soybean varieties. Soyasapogenol A glucosides (SAGs) including fully-acetylated SAGs (FSAGs), partially-acetylated SAGs (PSAGs), deacetylated SAGs (DSAGs), and DDMPs were identified by LC-PDA-MS/MS and quantified by UV-chromatograms. The complexity of soyasaponin compositions depended on the seed structure (hypocotyls and cotyledons) and variety. Other than in seed hypocotyls, FSAGs were detected in seed cotyledons ranging from 2.1 to 34.9 μmol/100 g dry basis. Minor components as PSAGs were also detected including monoacetyl, diacetyl, and triacetyl ranging between 2.2-19.8 and 1.6-44.0 μmol/100 g dry basis for hypocotyls and cotyledons, respectively. The degree of acetylation affects the intensity of undesirable characteristics in soy products and this issue requires further study. All saponin compositions require clarification using tandem mass spectrometry.