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.
Highlights
For the autonomy of the processing industry, it is necessary to use cultivars of adequate shape and size and lack of physiological disturbances besides a high content of soluble solids, dry mass and light coloring after frying (Keijbets, 2008)
Significant differences were observed by the F test, with interaction between the period and treatments for all variables analyzed, except for percentage of reducing sugars, which obtained influence only of the treatment
Singh and Kaur (2016) state that when potato tubers are placed under storage conditions with temperatures above 15 °C, a sharp increase in respiration occurs, as seen in the present work
Summary
For the autonomy of the processing industry, it is necessary to use cultivars of adequate shape and size and lack of physiological disturbances besides a high content of soluble solids, dry mass and light coloring after frying (Keijbets, 2008). The consumption of processed potatoes has been increasing as a result of the changes in diets, the increase in fast food chains and the need for semi-finished foods. To meet the processed potato market, it is necessary to cultivate the land and the refrigeration industry for quality maintenance and constant supply. Refrigerated storage is performed to maintain the quality of the potatoes by reducing respiration and inhibiting sprouting, and for constant supply to the industry. Over the cold chamber unloading and post-harvest handling process, tubers are subject to mechanical damage caused by impact, compression, vibration, cuts and cracks, inducing a series of physiological responses which results in the reduction in the quality
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