Mechanical properties affecting slicing performance of potatoes

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Laza, Miruna
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The purpose of this work was to examine the effect of thermal treatment and artificial turgor adjustment on various mechanical properties of potatoes throughout the storage season. Specimens taken from two potato cultivars (Russet Burbank and Shepody) of two different solids contents were subjected to small strain oscillatory shear tests, wedge fracture tests and notched-specimen tensile tests. The degree of feathering on the two new surfaces following the wedge fracture test was quantified. The specimens were prepared from control (8C) and pre-heated (33, 47 or 60C) samples of Russet and Shepody potatoes with both high and low solids content. Prior to testing, specimens were osmotically adjusted in a mannitol solution of 3%, 5% or 7%. The small strain oscillatory shear tests were performed at 1 Hz frequency and stresses ranging between 10 and 100 Nm-2. The wedge-penetration fracture tests and the tensile tests were both performed at cross-head speeds of 20 mm min-1. All the measurements were performed at room temperature (23 +- 1C). The tests were repeated every month from November to June. Measurements of turgor pressure and specific gravity were also performed during the storage time, for both Russet and Shepody potatoes. (Abstract shortened by UMI.)