Determination of Soyasaponins I and βg in Raw and Cooked Legumes by Solid Phase Extraction (SPE) Coupled to Liquid Chromatography (LC)−Mass Spectrometry (MS) and Assessment of Their Bioaccessibility by an in Vitro Digestion Model

Legumes contain a rich variety of phytochemicals as soyasaponins, triterpenoidal glycosides that possess multiple health-promoting properties, such as lowering of cholesterol. In this work, the quantification of soyasaponins I and βg in 60 raw and cooked legumes by using a solid phase extraction (SPE) coupled to a liquid chromatography (LC)−mass spectrometry (MS) method was carried out. Results showed that lentils are a good source of soyasaponins, with a content of soyasaponin I that ranged from 636 to 735 mg kg−1 and of soyasaponin βg from 672 to 1807 mg kg−1. The cooking process produced a small loss of soyasaponins in water, that is, 4.8−8.7%, and partially converted soyasaponin βg into soyasaponin I. In addition, the bioaccessibility of soyasaponins I in lentils was studied; the values ranged from 8.9 ± 0.3 to 10.6 ± 1.1% in the duodenal compartment. On the basis of these results, soyasaponins could be effective in lowering exogenous cholesterol.