Phenols, lignans and antioxidant properties of legume and sweet chestnut flours

Total phenols (TPC) and antioxidant properties were determined in chick-pea, green and red lentils and sweet chestnut flours, in both aqueous-organic extracts and their residues, by the Folin Ciocalteau method and by the FRAP assay, respectively. Plant lignans were quantified in flours by means of HPLC. In addition, the FRAP of plant lignans (secoisolariciresinol, lariciresinol, isolariciresinol, pinoresinol, matairesinol), their mixture and enterolignans (enterodiol and enterolactone) were determined. In all flours, the highest TPC values were found in the residue. Specific and varietal significant differences were observed in all parameters. The highest TPC (737.32 and 1492.93 mg/100 g d.w.) and FRAP (140.32 and 101.25 μmol/g d.w.) values were reached by green lentils in both aqueous-organic extract and residue, respectively. Sweet chestnuts had the highest total lignans (980.03 μg/100 g d.w.). It was also found that the plant lignans standards have a higher antioxidant activity than enterolignans standards and that matairesinol has the highest activity.