Lignin as natural radical scavenger. Study of the antioxidant capacity of apple tree pruning lignin obtained by different methods

In the present work, the antioxidant activity of lignins obtained from apple tree pruning was studied. Different procedures were used (autohydrolysis, organosolv and soda processes) and several operation conditions, techniques and methodologies were applied (ultrafiltration and differential precipitation). The obtained lignin samples were characterized by ATR-IR and TGA techniques, and the total phenolic content (Folin- Ciocalteau method) was determined. The antioxidant activity results (evaluated by ABTS assay) showed that: (1) the lignin obtaining process highly affects this property and (2) that the antiradical power of lignin was similar to that observed for two powerful natural antioxidants, gallic acid and catechin, and a commercial one, Trolox®. © 2011, AIDIC Servizi S.r.l.