Oxidative behaviour of fresh-cut 'Fuji' apples treated with chemical stabilizers

In this work, apples (Malus domestica L. 'Fuji') were minimally processed and treated with commercial products generally used to prevent browning, softening and diseases. The oxidative behaviour of fresh-cut apples was assessed during cold storage determining the changes in levels of hydrogen peroxide (14202), peroxidation, and changes in the activity of antioxidant enzymes; superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and peroxidase (POX, EC 1.11.1.7). Immediately after treatment, the samples treated with the antioxidant mixture (ascorbate + cysteine) exhibited a sharp increase in H2O2 levels and higher levels of peroxidative damage, especially at the beginning of the storage period. In line with this result, the treated fruits also exhibited a significant decrease in POX activity, but no significant changes in SOD and CAT activity during the first days of storage. H2O2 accumulation was not due to the action of cysteine but attributable to a specific action of ascorbate, which acted as a pro-oxidant under these conditions. Collectively, the results presented in this work showed that the commercially available antioxidant mixture generally used to prevent browning in fresh-cut apples may cause important oxidative damage. New alternatives are therefore required to prevent the detrimental loss of texture resulting from this oxidative action.