Liberation of insoluble-bound phenolics from lentil hull matrices as affected by Rhizopus oryzae fermentation: Alteration in phenolic profiles and their inhibitory capacities against low-density lipoprotein (LDL) and DNA oxidation.

• Insoluble-bound phenolics were significantly reduced in lentil hulls upon fermentation. • Contents of phenolics, kaempferol tetraglucoside and quercetin were increased upon fermentation. • Bioconversion of insoluble-bound to soluble phenolics was noticed only for a few phenolics upon fermentation. Fermentation is an effective non-thermal food processing operation used for enhancing the nutritional and functional properties of food. HPLC-ESI-MS/MS analysis and inhibitory capacity of the soluble- and insoluble-bound phenolics in lentil hulls in retarding the oxidation of LDL and DNA strand scission were determined following fermentation. In HPLC-ESI-MS/MS analysis, most insoluble-bound phenolics in lentil hulls were significantly decreased, indicating their liberation from the cell wall matrix upon fermentation. However, the released insoluble-bound phenolics did not show an efficient conversion into the bioavailable soluble phenolics as reflected in the inhibitory capacity against oxidation of LDL and DNA strands. The low efficiency in bioconversion from insoluble-bound to soluble phenolics might be due to the loss of the released bound phenolics during the fermentation process. Following the alterations of individual insoluble-bound phenolics in legumes upon fermentation in this work may fill the existing gap in the related areas. [ABSTRACT FROM AUTHOR]