Effects of Feed Rate and Screw Speed on Operating Characteristics and Extrudate Properties During Single‐Screw Extrusion Cooking of Rice Flour

Abstract

Cereal Chem. 76(2):236-242Rice flour (37% moisture content) was used to examine the effects of feed rate and screw speed on the specific energy input during single-screw extrusion cooking. Torque, raised by decreasing screw speed or increasing feed rate, was found to be a power law function of the ratio of feed rate to screw speed (F r /S s ) with r 2 > 0.94. Specific mechanical energy (SME) calculated from torque also was a power law function of F r /S s with r 2 >0.84 and negative power law indices. The SME obtained was in the 225-481 kJ/kg range. Thus the extruder can be considered low shear. Increasing SME raised the die temperature and decreased both intrinsic viscosity and water absorption index (WAI). The degree of gelatinization and intrinsic viscosity of extrudates also were power law functions of F r /S s . The intrinsic viscosity correlated well with the degree of gelatinization, WAI, and cooking loss, and appeared to be a good index of the extrudate properties. Different screw profiles also affect torque measurement.

Effect of Specific Mechanical Energy on <i>In-Vitro</i> Digestion and Physical Properties of Extruded Rice-Based Snacks

“…This result is consistent with the results reported in previous studies [13] [17] [32]. In an extruder, part of the mechanical energy input is converted to thermal energy through mechanical shearing.…”

Concoct Citrus Waste based Extruded Snacks: Optimizing Process Conditions Using Response Surface Methodology (RSM) and Delving Extrudate Attributes

“…Similar observations were recorded by Yeh and Jaw (1999) in rice extrudates. Increasing the screw speed lead to detraction in torque but the effect of increased screw speed was not compensated by it.…”

Effects of processing conditions and the use of modified starch and monoglyceride on some properties of extruded rice vermicelli

“…Surface gelatinization of traditional extruded noodles has been shown to be critical for hot-water stability of the noodles (Resmini, Lenner, Debernardi, & Gerardo, 1979). The extruded rice vermicelli at 90:100:100 showed cooking loss at 7.1 g/100 g dry noodle (dry weight basis) which is within the accepted range for commercial noodle (less than 12.5% wet weight basis or about 14.2% as dry weight basis; Yeh et al, 1999). The cooking loss of rice noodles made from traditional method was in the range of 7.5-12.5% (wet weight basis) (Yeh, Hsiu, & Shen, 1990).…”