Description

Abstract: A mixture of partially defatted peanut flour (12% fat) and rice flour was extruded to produce indirectly, puffed extrudates using a corotating twin-screw extruder. Extrudates were dried to obtain half-products of 11-12% moisture Content, and the half-products were expanded by deep-fat frying. The effects of three levels of peanut flour (30, 40, and 50%), screw speed (200, 300, and 400 rpm) and feed rate (4, 5, and 6 kg/h) were studied by characterizing the cellular structure of expanded snack products using Scanning Electron Microscopy (SEM). Average cell size (mm2) and the number of cells per unit area (cm2) were determined from the interior cross-section area of snack products. Those parameters were influenced mainly by the level of peanut flour followed by screw speed and feed rate. Increasing peanut flour from 40 to 50% produced less puffed final products resulting in small cell size compared to snacks of 30 – 40% peanut flour. The maximum cell size was produced in the snack products extruded with peanut flour of 30 – 40% at screw speed of 250 – 330 rpm and feed rate of 4.7 – 5.7 kg/h. While the number of cells was relatively similar regardless of screw speed and feed rate, increasing peanut flour increased the number of cells. The cell walls became thicker with increasing feed rate.