Improved folate monoglutamate extraction and application to folate quantification from wild lentil seeds by ultra-performance liquid chromatography-selective reaction monitoring mass spectrometry

Abstract

Folates are important micronutrients in lentils (Lens culinaris Medik.). In this work, the folate extraction workflow in ascorbate-containing buffer was optimized and validated, and the concentrations of eight folate monoglutamates in cultivated and six wild lentil species, grown under field or greenhouse conditions, were quantified by ultra-performance liquid chromatography and mass spectrometry (UPLC-MS). In general wild lentil species had higher folate concentrations than cultivated genotypes. Lens tomentosus had the highest folate concentration with median values of 439.7 and 360.9 μg/100 g in the field and greenhouse, followed by Lens orientalis with 416.6 and 327.6 μg/100 g, respectively. A significant effect (P < 0.05) of growing conditions was observed in four out of six wild lentil species, with seeds from the field having higher folate concentration (6% to 45%) compared with the greenhouse. MeFox, an oxidation product of 5-methyltetrahydrofolate, was present in all lentil species at concentrations 2.2 to 5.6 times higher than the total folates.