De-oiling and Pre-treatments for High-Quality Potato Chips
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A de-oiling step using a centrifuge ensures oil content reduction and improves the quality of fried snacks. A commercial deep-fat fryer with the basket loaded with potatoes and a sample holder was used to fry potato slices, non-pretreated, blanched in hot water (85°C/3.5min) and rinsed in 3 percent NaCl solution (25°C/5min). A de-oiling step (350 1 rpm and 457 1 rpm) for 1 min was conducted after the frying (145°, 165° and 185°C or 165°C) and cooling (0, 15, 30, 45 and 60 s or 0.60 and 120 s) steps. Lower frying temperature, higher centrifuge speed, and shorter cooling time resulted in the lowest oil uptake in potato chips. Pre-treatments (blanching and soaking) decreased (5 percent and by at least 10 percent), respectively, compared to the untreated chips. De-oiling led to increased hardness of the chips fried at 145° and 165°C (0 s cooling time), and the hardness decreased as cooling time. Pre-treatments (blanching and soaking) increased hardness (by 46 percent and 38 percent) and decreased work (by 20 percent and 27 percent), respectively, so that, during rupture, the pre-treated chips resulted in more crunchiness and firmness than the untreated chips. Potato chips showed less lightness and redness when fried at 145°C, and more lightness and redness when fried at 185°C; yellowness increased b* values as temperature increased. As cooling time increased, the lightness of the chips decreased, and the redness and the yellowness of the chips increased. Pre-treated samples resulted in increasing in lightness (L*) and yellowness (b*), whereas the redness (a*) values of the final products fluctuated. Higher frying temperature, centrifuge speed, and higher cooling time usually resulted in increasing shrinkage in thickness of potato chips; the chips fried at 165°C resulted in increasing in thickness. All the fried and de-oiled products resulted in a decrease in thickness, diameter, and volume except for the thickness of the chip soaked in NaCl, compared to raw slices. A consumer test showed that, blanching and de-oiling without cooling enhanced texture and overall quality of the chip, soaking and de-oiling improved the color, flavor, and the overall quality, and the two pre-treatments did not significantly influence the odor of the chip.
Kim, Tae Hoon (2010). De-oiling and Pre-treatments for High-Quality Potato Chips. Master's thesis, Texas A&M University. Available electronically from