The effect of preliminary processing and different methods of cooking on the iodine content and selected antioxidative properties of carrot (Daucus carota L.) biofortified with (potassium) iodine

Carrot is a vegetable that contains many nutrients and has strong antioxidant activity as well as pro-health potential. The level of bioactive compounds is strongly connected with the production chain. The thermal treatment of food products induces several biological, physical and chemical changes. In this study, changes in the levels of iodine, total carotenoids, total polyphenols as well as the antioxidant activity of unpeeled and peeled controls and carrots biofortified with (potassium) iodine (KJ) during cultivation due to the cooking and steaming process were investigated. The use of thermal processes resulted in a lower concentration of iodine in the roots of the control as well as in carrots biofortified with (potassium) iodine. In addition, peeling carrots caused higher losses of this trace element in the control and the biofortified carrots cooked or steamed for various times. In this study, a significant growth of the total carotenoids in peeled carrots biofortified with (potassium) iodine and of the total polyphenols in unpeeled carrots biofortified with (potassium) iodine under the influence of the cooking and steaming processes was observed compared with raw peeled and unpeeled biofortified carrots, respectively. Antioxidant activity significantly increased in the unpeeled and peeled carrots biofortified with (potassium) iodine under all thermal treatments in comparison with the raw unpeeled and peeled biofortified carrots.