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Oil Absorption Characteristics of a Multigrain Extrudate During Frying: Effect of Extrusion Temperature and Screw Speed¹

¹Journal Series No. 11429, Agriculture Research Division, University of Nebraska-Lincoln. ²Former research assistant, research associate, and associate professor. Cereal/Oilseed Science & Technology Laboratory, Dept. of Food Science & Technology, University of Nebraska-Lincoln, NE 68583-0919. ³Corresponding author. Phone: 402-472-2814. Fax: 402-472-1693. E-mail: djackson@unlnotes.unl.edu

The oil absorption characteristics of a multigrain extruded and fried snack product were studied as a function of extruder screw speed and cooking temperature using a central composite response surface methodology (RSM). The extruded product was produced using a corotating twin screw extruder, dehydrated to a uniform moisture content, and subsequently deep-fat-fried at 192 ± 1°C for 10–40 sec to complete expansion. Significant RSM models were developed for oil absorption and extrudate water absorption index (WAI). According to the lowest oil model, absorption (19.9%) was obtained with an extruder screw speed of 218.6 rpm and a cooking temperature of 117.8°C. WAI reached a maximum at a screw speed of 221.9 rpm and a cooking temperature of 109°C. Oil absorption characteristics and extrudate WAI were significantly correlated (r= -0.84, P = 0.0002). The data suggest that extrusion conditions can be optimized to influence the physicochemical structures in the extrudate matrix so that oil absorption can be minimized.