Antioxidant activity of phenolic extracts from chestnut fruit and forest industries residues

In this work, extracts from various lignocellulosic wastes were analyzed with the aim of applying them to prevent colour ultraviolet degradation of dyed veneers used for board coating. Chestnut fruit (Castanea sativa) shell and bur, barks from Pinus pinaster, Eucalyptus globulus, Quercus frainetto and Quercus robur and wood from Tilia cordata were extracted using water or aqueous solutions of sodium sulphite and/or sodium hydroxide. The extracts were analyzed for their antioxidant activity (using the ferric reducing antioxidant power, the free radical DPPH and the free radical ABTS essays), totals phenols content, molecular weight distribution and phenolic composition. Except for chestnut bur and steam peeled chestnut shell whose water extract was the best, the best antioxidant properties were obtained for the 2 % sodium sulphite extracts. Extracts from pine bark and steam peeled chestnut shell, with the highest total phenols content and antioxidant activity, not only showed the best properties as bioprotectors but also high extraction yields. These extracts also presented the higher average molecular weights. Extract antioxidant properties were related to the presence of various phenolic compounds identified by reverse phase high-performance liquid chromatography electrospray ionization time-of-flight mass spectrometry: flavan-3-ols, flavonols, flavonol glycosides, dihydroflavonols and phenolic acids.