Properties of tomato powders as additives for food fortification and stabilization

The antioxidant activities of two freeze-dried tomato powders as additives for food fortification and stabilization were studied. The two tomato powde rs were obtained from the whole fruit and from the pulp after "serum" separ ation, respectively. The antioxidant activity was studied by measuring (a) the inhibition of the singlet oxygen-catalyzed oxidation of alpha -linoleni c acid, in the presence or absence of copper ions, as a model of the oxidat ive processes occurring in foods, and (b) the inhibition of xanthine oxidas e (XOD)- and myeloperoxidase (MPO)-catalyzed reactions and copper-induced l ipid peroxidation. The partial separation of "serum" decreased the freeze-d rying time by 50%. The partially fractionated tomato powder had a 60% lower phenolic content and an Ii-fold higher lycopene content than the whole tom ato powder, on a dry weight basis. Ascorbic acid was almost completely remo ved by fractionation. Both the powder obtained from the whole tomato and th at obtained from the partially fractionated tomato had antioxidant activity in all the model systems used. Based on these results, we conclude that to mato powders have multifunctional properties, which could address the preve ntion of oxidative degradations both in foods and in vivo. Therefore, tomat o can be regarded as source of food additives for fortification and stabili zation, even if it is submitted to technological processes that can cause t he loss of the more labile hydrophilic antioxidants.