Antioxidant activity of liquors from aqueous treatments of Pinus radiata wood

Non-isothermal, aqueous treatments of Pinus radiata wood were carried out to reach maximal temperatures in the range 210–240°C, and the liquors from the treatments were analysed for phenolic content and antioxidant activity using several tests (α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical scavenging, Trolox equivalent antioxidant capacity, β-carotene bleaching and reducing power). Increased severity resulted in increased yields in phenolics (up to 1.5 g phenolic compounds/100 g oven-dry wood) and improved antioxidant activity. The DPPH radical scavenging capacity of compounds present in autohydrolysis liquors and the β-carotene bleaching ability of the compounds extracted with ethyl acetate from liquors were higher than those of synthetic antioxidants. The fractions solubilised in autohydrolysis treatments were also effective as hydroxyl and ABTS radical scavengers. The autohydrolysis liquors and their ethyl acetate soluble fraction showed reducing power in the range reported for extracts from other natural sources.