The solvent gradient elution program is described in detail in HaÈ kkinen et al. (1998). It was modified from the method of Lamuela-Ravento s and Waterhouse (1994), described originally for measurement of wine phenolics. The flow rate was 0.5 ml minÿ1 and injection volume was 20 ml. Development and validation of the method has been described in detail by HaÈ kkinen et al. (1998).