Horseradish (Armoracia rusticana, syn. Cochlearia armoracia), white cabbage (Brassica oleracea var. capitata f. alba), garden cress (Lepidium sativum), radish (Raphanus sativus) and papaya fruit (Car- ica papaya L.) were obtained from a local store and Beneforte broc- coli florets (Brassica oleracea L. var. italica) were obtained from Tesco supermarket (Ireland). Vegetables were freeze-dried, ground and stored at 20 C until investigation.