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Specific Mechanical Energy (specific + mechanical_energy)

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Chemistry	100%

Selected Abstracts

EXTRUSION COOKING OF BLENDS OF SOY FLOUR AND SWEET POTATO FLOUR ON SPECIFIC MECHANICAL ENERGY (SME), EXTRUDATE TEMPERATURE AND TORQUE

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2001
M. O. IWE
Defatted soy flour and sweet potato flour containing 18% moisture were mixed in a pilot mixer, and extruded in an Almex-Bettenfeld single-screw extruder operated at varying rotational speed and die diameter. A central composite, rotatable nearly orthogonal design, which required 23 experiments for three factors (feed composition (fc), screw speed (ss) and die diameter (dd)) was developed and used for the generation of response surfaces. Effects of the extrusion variables on specific mechanical energy (SME), extrudate temperature (ET), and torque (T) were evaluated using response surface analysis. Results showed that product temperature increased with increases in die diameter, screw speed and feed composition. However, the effect of die diameter was greater than those of screw speed and feed composition. Decrease in die diameter with increase in sweet potato content increased torque. Screw speed exhibited a linear effect on torque. [source]

Effect of extrusion parameters on flavour retention, functional and physical properties of mixtures of starch and d -limonene encapsulated in milk protein

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2006
Sri Yuliani
Summary The purpose of this research was to investigate the retention of flavour volatiles encapsulated in water-insoluble systems during high temperature,short time extrusion process. A protein precipitation method was used to produce water-insoluble capsules encapsulating limonene, and the capsules were added to the extruder feed material (cornstarch). A twin-screw extruder was used to evaluate the effect of capsule level of addition (0,5%), barrel temperature (125,145 °C) and screw speed (145,175 r.p.m.) on extruder parameters (torque, die pressure, specific mechanical energy, residence time distribution) and extrudate properties [flavour retention, texture, colour, density, expansion, water absorption index, water solubility index (WSI)]. Capsule level had a significant effect on extrusion conditions, flavour retention and extrudate physical properties. Flavour retention increased with the increase in capsule level from 0% to 2.5%, reached a maximum value at capsule level of 2.5% and decreased when the capsule level increased from 2.5% to 5%. The die pressure, torque, expansion ratio, hardness and WSI exhibited the opposite effect with the presence of capsules. [source]

EXTRUSION COOKING OF BLENDS OF SOY FLOUR AND SWEET POTATO FLOUR ON SPECIFIC MECHANICAL ENERGY (SME), EXTRUDATE TEMPERATURE AND TORQUE

Evaluating Energy Consumption and Efficiency of a Twin-Screw Extruder

JOURNAL OF FOOD SCIENCE, Issue 5 2002
M. Liang
ABSTRACT: Using the results from twin-screw extrusion of corn meal, both energy consumption and extruder efficiency were found to be significantly correlated with screw speed and specific feeding load (SFL). An increase in the SFL decreased the total specific mechanical energy, but increased the extruder efficiency. SFL influenced the extruder efficiency more than the screw speed. Increasing the screw speed from 300 to 450 rpm at a constant SFL level increased the extruder efficiency by 6 to 11%, whereas an increase of SFL from 0.0026 to 0.0038 kg rev 1 raised the extruder efficiency by 30%. Of the mechanical energy consumed per unit mass of extrudate, over 98% were used for shearing or viscous dissipation and less than 1.5% were for pumping during twin-screw extrusion of corn meal. [source]

Development of a bulgur-like product using extrusion cooking

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2003
Hamit Köksel
Abstract In this study we (1) developed a new bulgur-like foodstuff using a durum wheat cultivar and an extrusion technique, (2) investigated the physicochemical properties of the extrudates produced and (3) sensorially evaluated the end-product after cooking. Durum wheat was processed in a laboratory-scale co-rotating twin-screw extruder with different levels of moisture content of the feed (367, 417 and 455,g,kg,1), screw speed (150 and 200,rpm) and feed rate (2.4 and 2.9,kg,h,1) to develop the bulgur-like product. The effects of extrusion conditions on system variables (die pressure and specific mechanical energy (SME)), physical properties (die swell and bulk density), pasting properties (peak, trough and final viscosities) and cooking and sensory properties of the bulgur-like products were determined. The results indicated that increased feed moisture content resulted in significant decreases in the die pressure and SME values of the extruded durum wheat products. As the moisture content and screw speed increased, the changes in die swell values were not significant. The lowest die swell and highest bulk density values were obtained at the highest feed moisture content. The extrusion variables also affected the pasting properties of the extrudates. Significant increases in each of the pasting properties occurred when the moisture content of the feed was increased. Some of the sensory properties (bulkiness, firmness, stickiness and taste,aroma) improved significantly as the feed moisture content increased, indicating better quality. Increased feed moisture content significantly improved cooking quality as determined by a decrease in colorimetric test results. Extrusion seems to be promising for the production of dry, relatively inexpensive bulgur-like products with acceptable sensory properties. © 2003 Society of Chemical Industry [source]

Effect of the addition of calcium hydroxide on some characteristics of extruded products from blue maize (Zea mays L) using response surface methodology

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2001
José J Zazueta-Morales
Abstract The aim of this research was to study the effects of calcium hydroxide (0,0.2%) and screw speed (100,180,rpm) on the expansion index (EI), bulk density (BD), penetration force (PF) and specific mechanical energy (SME) values of blue maize meal extrudates. Blue maize meal was extruded using a commercial extruder (Brabender 20DN/8-235-00) with a compression screw ratio of 3:1. A second-order, central composite experimental design was used. It was found that the EI and SME values decreased and the BD and PF values increased when the calcium hydroxide concentration was increased. The screw speed had a significant effect only on the SME and PF values. Quadratic model fitness was shown for all responses, with values of R2,>,0.74, p of F (model) <0.01 and variability coefficient <13.3% (except for PF, 29.18%), and for almost all cases there was no lack of fit (p,>,0.055). Calcium hydroxide concentration showed good correlation (p,<,0.01) with EI (r,,=,,0.81), PF (r,,=,0.60), SME (r,,=,,0.76) and BD (r,,=,0.83). However, screw speed was marginally or not correlated (r,<,0.36, p,>,0.14) with the responses. The results suggest that it is possible to produce appropriate extruded products from blue maize fortified with calcium in an optimised calcium hydroxide concentration and screw speed range of 0.02,0.078% and 117,180,rpm respectively. © 2001 Society of Chemical Industry [source]