Abstract

Mechanical damage and storage conditions may alter carbohydrate metabolism and oxidative enzyme activity, causing darkening and impairing the use of tubers in pre-fried potato processing industry. The objective of this study was to evaluate the enzymatic changes and carbohydrate metabolism of ‘Markies’ potato tubers subjected to mechanical damage and exposed to high temperatures before processing. The tubers were stored for 4 months at 8 °C, and further divided into treatment with impact and abrasion damage; and control treatment, in which the tubers were not damaged. Afterwards, they were stored at 28 °C room temperature, evaluated for loss of accumulated fresh mass (FML); total soluble sugar (TSS), reducing sugar (RS) and non-reducing sugar (NRS); color after frying and activity of polyphenoloxidase (PPO) and peroxidase (POD) at 0, 12, 24, 36 and 48 h after placed at room temperature. The mechanical damages incremented FML, RS, PPO and TSS, NRS and POD up to 35.6, 34, and 22 h, respectively. Regardless of the occurrence of mechanical damage and the period of evaluation, the sticks showed a light color after frying and were classified in category 2. The increase in the evaluation time led to the rise in FML and the PPO activity. It is concluded that the mechanical damages increase the FML and cause darkening of the tips of the sticks after frying, however this variety still display qualities that are suitable for industrial processing.

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