Fig. 2
From: Origin and characterisation of the extractable colour of oak heartwood used for ageing spirits
Example of fractionation of and characterisation of extractable oak heartwood colour. Firstly pre-fractionation is obtained by low-pressure chromatography on Sephadex LH20-100 column (20 × 2 cm, flow rate, 3.5 mL/mn, detection 280 nm for phenols and 420 nm for colour) of oak acetone/water (7/3) extract (1 g of dry wood/100 mL solvent). Fraction I was obtained by water elution, fraction II, by 30% MeOH and Fraction III by 100% MeOH solvent. a Inner heartwood, b outer heartwood. Secondly each pre-fraction are analysed after acetylation by high-performance size-exclusion chromatography (TSK G2000 PW column, 30 × 7.5 cm, solvent, MeOH + 1% H3PO4, flow rate 0.6 mL/mn, column calibrated by gallic acid G, ellagic acid E, castalin, castalagin, roburin D and grandinin). S: vescalin, castalin; M: monomer ellagitannins; D: dimer ellagitannins; P: polymeric ellagitannins. * Retentate measured by difference between Fr. I, II, III and total quantity of dry extract deposited on Sephadex column