Effect of Extrusion Variables on Cassava Extrudates

Cassava flour was extruded by varying parameters of feed moisture; temperature; screw speed and feed rate. We investigated significance of each variable and interactions between variables on each extrudate characteristic. Optimum expansion (2.82) was at 11% feed moisture 120–125 °C; screw speed, 520rpm; feed rate, 250g/min. Effect of feed moisture was most significant on expansion, bulk density and extrudate moisture. Increasing temperature, increased expansion and water solubility, but decreased bulk density, extrudate moisture and water absorption. Screw speed most influenced water absorption and solubility. Extrudate moisture correlated negatively (P<0.01) with extrudate expansion. Water solubility index of extrudate negatively correlated (P<0.05) with extrudate moisture and water absorption index but correlated positively (p<0.05) with expansion.     

Selected properties of native or modified maize starch/soy protein mixtures extruded at varying screw speed

Mixtures of soy protein isolate and native or modified (crosslinked) maize starch were extruded in a twin‐screw extruder at screw speeds of 80, 120 and 160 rpm and a moisture content of 250 g kg^?1 (dry basis). Increasing screw speed did not affect the specific mechanical energy and water solubility and absorption indices but did affect the sectional expansion index and bulk density, as the flow rate of the feed was not held constant during extrusion. The sectional expansion indices of modified starch/soy protein mixtures were higher than those of native starch/soy protein mixtures, suggesting an effect of feed material in addition to phase transition on the expansion of extrudates containing soybean. Since the bulk densities of modified starch/soy protein mixtures were lower than those of native starch/soy protein mixtures, it appears that bulk densities of extrudates containing high percentages of soy protein can be reduced by the presence of crosslinked starch in the feed. Copyright © 2005 Society of Chemical Industry     

螺杆转速和原料含水率对糯米单螺杆挤出过程的影响

本文利用组合实验研究了糯米单螺杆挤出过程中操作参数(螺杆转速、原料含水率]对挤出设备和产品性能(生产率、功耗、度电产量、膨化指数、吸水指数、水溶性指数)的影响,建立了相互影响关系的回归方程,得出随螺杆转速的增加,生产率、功耗、水溶性指数增大,而度电产量、膨化指数、吸水指数开始上升,然后下降,存在极大值,综合各指标,该设备的最佳螺杆转速在240—260rpm;随原料含水率的增加,生产率、度电产量、吸水指数增加,而功耗、膨化指数、水溶指数减小,该设备挤出膨化糯米时的最佳原料含水率在18％～21％范围内。     

Mechanical and microstructural properties of soy protein – high amylose corn starch extrudates in relation to physiochemical changes of starch during extrusion

Mechanical and microstructural properties of expanded extrudates prepared from blends of high amylose corn (Zeamays L. ssp. Mays) starch (HACS) and soy protein concentrate (SPC) were studied in relation to the physicochemical changes in starch. Effects of screw speed (230 and 330 rpm) and SPC level (10%, 20%, 30% and 50%) on expansion and mechanical properties were determined. Compared with 230 rpm, screw speed at 330 rpm resulted in increased specific mechanical energy, expansion ratio, water absorption and water solubility indices and decreased bulk density and piece density. Varying screw speeds did not significantly affect the mechanical strength of extrudates or starch molecular weight distribution. Bulk and piece densities, and water absorption index (WAI) only slightly increased or exhibited no significant trends as SPC level increased to 20%. A substantial increase in bulk and piece densities and decrease in expansion ratio and WAI were observed as SPC level increased from 20% to 30%. The trends were either reversed or moderated as SPC increased to 50%. These results in combination with average crushing force and water solubility index data provided a significant insight into the interactions between HACS and SPC during extrusion processing. As compared to an earlier baseline study by our research group on normal corn starch – SPC extrudates, results from the current study indicated that the expansion of extrudate containing HACS alone was lower than that of extrudates containing normal corn starch. However, expansion of the HACS–SPC blends was not significantly impacted at 10–20% SPC levels, whereas the expansion of normal corn starch was significantly reduced.     

Effects of extrusion variables on the properties of waxy hulless barley extrudates

The objective of this research was to investigate the extrudability of waxy hulless barley flour under various extrusion conditions. Waxy hulless barley flour was processed in a laboratory-scale corotating twin-screw extruder with different levels of feed moisture content (22.3, 26.8, and 30.7%) and die temperature (130, 150, and 170 degrees C) to develop a snack food with high beta-glucan content. The effects of extrusion condition variables (screw configuration, moisture, and temperature) on the system variables (pressure and specific mechanical energy), the extrudate physical properties (sectional expansion index, bulk density), starch gelatinization, pasting properties (cold peak viscosity, trough viscosity, and final viscosity), and beta-glucan contents were determined. Results were evaluated by using response surface methodology. Increased extrusion temperature and feed moisture content resulted in decreases in exit die pressure and specific mechanical energy values. For extrudates extruded under low shear screw configuration (LS), increased barrel temperature decreased sectional expansion index (SEI) values at both low and high moisture contents. The feed moisture seems to have an inverse relationship with SEI over the range studied. Bulk density was higher at higher moisture contents, for both low and high barrel temperatures, for samples extruded under high shear screw configuration (HS) and LS. Cold peak viscosities (CV) were observed in all samples. The CV increased with the increase in extrusion temperature and feed moisture content. Although beta-glucan contents of the LS extrudates were comparable to that of barley flour sample, HS samples had generally lower beta-glucan contents. The extrusion cooking technique seems to be promising for the production of snack foods with high beta-glucan content, especially using LS conditions.     

Effects of Extrusion Process Variables on Quality Properties of Wheat-Ginseng Extrudates

The present study investigated the effects of extrusion process variables (feed moisture, screw speed, and barrel temperature) on the physical [expansion ratio, water absorption index (WAI), and water solubility index (WSI)], pasting, and thermal properties of wheat-ginseng extrudates (WGE). A wheat flour-ginseng powder (GP) blend (10% GP, w/w) was extruded in a twin-screw extruder (L/D ratio of 25:1) with full factorial combinations of feed moisture (25, 30, and 35%), screw speed (200 and 300 rpm), and zone 5 barrel temperature (110, 120, 130, and 140°C). The expansion ratios of WGE were significantly increased with decreasing feed moisture, decreasing screw speed, and increasing barrel temperature. Increasing feed moisture significantly increased WAI values of WGE and significantly decreased WSI values of WGE. However, an increase in either screw speed or barrel temperature caused a significant decrease in WAI values of WGE and a significant increase in WSI values of WGE. Rapid visco analyzer peak viscosity values of WGE were significantly affected by changes in extrusion process variables studied, indicating that the degree of starch degradation and/or gelatinization in WGE is a very important factor associated with their peak viscosity. WAI values of WGE were positively correlated (r = 0.88, p ≤ 0.001) with peak viscosity values of WGE samples, whereas WSI values of WGE samples were negatively correlated (r = 0.82, p ≤ 0.001). Increasing feed moisture resulted in an increase in values of transition peak temperature (T_p) of WGE, whereas increasing screw speed and barrel temperature each led to a decrease in T_p values of WGE, determined by differential scanning calorimetry.     

Effect of Thermo-extrusion Process Parameters on Selected Quality Attributes of Meat Analogue from Mucuna Bean Seed Flour

Flour from mucuna beans (Mucuna pruriens) were used in producing texturized meat analogue using a single screw extruder with the intention to monitor modifications on some functional properties of the extrudate. Response surface methodology based on Box Behnken design at three levels of barrel temperature (110, 120, 130°C), screw speed (100, 120, 140 rpm) and feed moisture content (44, 47, 50%) were used in 17 runs. Regression models describing the effect of process variables on the product quality attributes were obtained. Result obtained showed that the moisture contents of the meat analogue samples decreased from 13.23 to 6.53%. Increasing feed moisture content resulted in extruded meat analogue with a higher density (0.988), water absorption index (WAI) (2.30), oil absorption index (OAI) (2.350), swelling power (3.47) and lower lateral expansion (0.84). Lateral expansion, OAI and swelling power increased as barrel temperature increased with peak values of 1.39, 2.39 and 3.47 respectively, while bulk density and WAI decreased. The product functional responses with coefficients of determination (R²) ranging between 0.658 and 0.894 were most affected by changes in barrel temperature and feed moisture and to lesser extent by screw speed. Optimization results based on desirability concept indicated that a barrel temperature of 120.15°C, feed moisture of 47% and screw speed of 119.19 rpm would produce meat analogue of preferable functional properties.     

Extrusion cooking properties of white and coloured rice varieties with different amylose content

Five white and coloured rice varieties with different AM contents (long grain rice: 34%, Thai Jasmine rice: 15%, glutinous rice: 7%, red rice: 18% and black rice: 5%) were pregelatinised using a twin‐screw extruder at a barrel temperature of 150°C and two levels of feed moisture (12 and 16%). The correlation of AM content to water absorption index (WAI), water solubility index (WSI), starting viscosity, hot viscosity and final viscosity of the five rice extrudates were determined. Total anthocyanin content (TAC), total phenolic content (TPC) and antioxidant activity of extrudates were analysed by spectrophotometric methods. AM content was positively correlated to WAI and final viscosity. High AM content of the rice varieties resulted in high WAI and high final viscosity of extrudates. In addition, higher feed moisture content (16%) increased WAI and pasting properties of rice extrudates, but decreased WSI. Extrusion cooking reduced TAC, TPC and antioxidant properties, but the remaining values were high enough to suggest a further use for (functional) food production.     

Effect of Extrusion Cooking on Functional Properties and in vitro Starch Digestibility of Barley-Based Extrudates from Fruit and Vegetable By-Products

ABSTRACT:  Barley flour and barley flour–pomace (tomato, grape) blends were extruded through a co-rotating twin-screw extruder. The aim of the present study was to investigate the effects of die temperature, screw speed, and pomace level on water absorption index (WAI), water solubility index (WSI), degree of starch gelatinization, and in vitro starch digestibility using a response surface methodology. The selected extrudate samples were examined further using differential scanning calorimetry (DSC) and polarized light microscopy, respectively. The WAI of barley–pomace extrudates was affected by increasing pomace level. Temperature had significant effect on all types of extrudate but screw speed had significant linear effect only on barley and barley–grape pomace extrudates on degree of starch gelatinization. Although no gelatinization peak was detected, an endotherm was observed on all selected extrudates. In general, extrusion cooking significantly increased in vitro starch digestibility of extrudates. However, increasing level of both tomato and grape pomace led to reduction in starch digestibility.     

Functional and Nutritional Properties of Extruded Whole Pinto Bean Meal (Phaseolus Vulgaris L.)

Pinto bean meals with 18, 20, and 22% moisture were extruded at 140,160 and 180°C, using screw speeds of 150,200 and 250 rpm in a single-screw laboratory extruded. Expansion index, bulk density, water absorption and solubility indices, in vitro protein digestibility, and trypsin inhibitor activity in extrudate were measured. Temperature and feed moisture influenced (p<0.05) expansion index, bulk density, water absorption index and in vitro protein digestibility. Water solubility index was affected by temperature only. Trypsin inhibitors were inactivated completely for all conditions. Screw speed had no effect on any dependent variable. Best product was produced with 22% feed moisture at 160°C.     

Effect of Process Conditions on the Physical and Sensory Properties of Extruded Oat-Corn Puff

ABSTRACT: The effect of processing variables, including screw speed (200,300, and 400 rpm), moisture content (18, 19.5, and 21%), and four different percentages (55,70,85, and 100%) of oat flour, on the extrudate physical properties (expansion, bulk density, and texture profiles) and sensory properties were studied. Increasing the percentage of oat flour resulted in extrudates with a lower specific length, higher bulk density, lower lightness, higher redness, lower yellowness, higher hardness, and lower springiness, gumminess, and chewiness. Higher moisture content reduced expansion, except for the 100% oat flour puffs. Screw speed had no significant effect on the bulk density, specific length, and expansion ratio. Principal Component Analysis showed that decreasing moisture content and increasing screw speed resulted in increased product temperature, which was highly correlated with attributes of a more expanded product such as lightness, crispness, shininess, and an open cell structure. With a higher screw speed and a higher product temperature, corn-related flavors were more likely to develop. High correlations between physical and sensory properties were observed.     

Extruded aquafeeds containing distillers dried grains with solubles: effects on extrudate properties and processing behaviour

BACKGROUND: The tremendous supply and low cost of distillers dried grains with solubles (DDGS) make it an attractive feedstuff for aquaculture diets. Also, several studies have shown that DDGS can be successfully fed to various finfish. The objective of this study was to evaluate the effects of inclusion rate of DDGS (0, 250, 500 g kg^?1), feed moisture content (350, 450 g kg^?1) and die opening area (die A = 18.85 mm², die B = 3988.45 mm²) on the properties of the extrudates and on processing behaviour using a single‐screw extruder. RESULTS: Increasing the inclusion rate of DDGS resulted in extrudates with lower unit density, bulk density, expansion ratio, water solubility index and brightness (Hunter L) but higher redness (Hunter a) and yellowness (Hunter b). The increase in moisture content affected the extrudate properties in different ways: it increased bulk density, Hunter L, Hunter b and mass flow rate, whereas specific mechanical energy decreased at high moisture content. Increasing the die opening area primarily decreased expansion ratio of extrudates, power consumption and barrel temperatures but increased mass flow rate. CONCLUSION: Extrudates from all treatments exhibited high durability and floatability, and less energy was required to produce extrudates when DDGS was used compared with soybean meal‐based diets. The aquaculture industry can use this information to develop high‐quality feeds at low cost. Copyright © 2011 Society of Chemical Industry     

EXTRUSION BEHAVIOUR AND PRODUCT CHARACTERISTICS OF BROWN AND MILLED RICE GRITS

ABSTRACT

Extrusion behaviour of milled and brown rice grits obtained from six rice cultivars (Jaya, IR-8, PR-103, PR-106, Pusa No.1 and Basmati 385) was investigated using Brabender single screw extruder. Feed moisture of the grits was adjusted to 16%, and extrusion cooking was done at barrel temperature of 150°C and screw speed of 100 rpm. The milled and brown rice grits from different rice cultivars differed significantly with respect to extrusion behaviour and extrudate characteristi cs. Extrudates obtained from milled rice grits showed higher die pressure, expansion, water absorption index (WAI) and water solubility index (WSI) as compared to those from brown rice. WSI of extrudates varied from 3.38 to 10.5%, WAI from 5.20 to 6.90, die pressure from 6068 to 9325 kPa and expansion from 7.52 to 11.30 respectively. The grits from cultivars which had lower length-breadth ratio and mealy endosperm resulted into more expanded extrudates and hence were found to be more suitable from extrusion.     

Influence of the extrusion parameters on the physical properties of chickpea and barley extrudates

In this research, the effects of extrusion processing [exit-die temperature (120–150°C), moisture content (20–24% wet basis), and screw speed (260–340 rpm)] on the specific mechanical energy and physical properties (expansion ratio, bulk density, and hardness) of desi chickpea and hullless barley extrudates were estimated using response surface methodology. Exit-die temperature and feed moisture content, as well as the interaction between them were the factors that affected the product responses the most. Significant correlation was found between the hardness and bulk density (positive), hardness and expansion ratio (negative), and bulk density and expansion ratio (negative) for both chickpea and barley extrudates. Desirable characteristics (high expansion, low bulk density, and hardness) for chickpea were obtained at high exit-die temperature, relatively high moisture, and high screw speed. As for the barley extrudates, high exit-die temperature, low moisture, and moderate to high screw speed were identified as optimal.     

Physical characteristics of extrudates from corn flour and dehulled carioca bean flour blend

Extruded products were prepared from a corn flour and dehulled carioca bean (Phaseolus vulgaris, L.) flour blend using a single-screw extruder. A central composite rotate design was used to evaluate the effects of extrusion process variables: screw speed (318.9–392.9 rpm), feed moisture (10.9–21.0 g/100 g) and bean flour level (4.8–55.2 g/100 g) on the specific mechanical energy (SME), sectional expansion index (SEI), longitudinal expansion index (LEI), volumetric expansion index (VEI) and density (D) of the extrudates. The instrumental texture was also analyzed. The independent variables had significant effects on the physical properties (SEI, VEI and density) of extrudates, with the exception of SME and LEI. SEI increased with increasing screw speed, but a higher moisture and bean flour content resulted in decreasing SEI and VEI. The increase of moisture and bean flour increased the density of extrudates. According to texture analysis, some treatments with 30 and 45 g/100 g bean flour did not show significant differences when compared to commercial brand snacks. However, when combined with higher moisture content (≥19 g/100 g) and lower screw speed (≤333 rpm), the results of the expanded product were not satisfactory.     

EFFECT of EXTRUSION VARIABLES ON EXTRUDATE CHARACTERISTICS of FISH MUSCLE-RICE FLOUR BLEND IN A SINGLE-SCREW EXTRUDER

Effects of extrusion variables on extrudate characteristics of fish muscle-rice flour blend containing intermediate moisture (30–50%) were studied in an indigenously developed single screw cooking extruder. Data analysis of the statistically designed response surface experiments showed that expansion ratio and bulk density of extrudates were most influenced by the barrel temperature followed by fish content of the feed. In contrast fish and moisture contents of the feed significantly influenced hardness. A set of optimum process conditions was arrived at 160C barrel temperature, 12% fish content and 27% moisture content. Under these conditions experimental expansion ratio and bulk density matched well with the values predicted from the response model, but hardness deviated significantly. Experimental properties of the extrudates were not, however, affected by the fish variety.     

Extrusion behaviour of grits from flint and sweet corn

Studies were conducted to investigate the effect of feed moisture, extrusion temperature and screw speed on the extrusion behaviour and product characteristics of flint and sweet corn grits. The extruder die pressure and extrudate properties, such as expansion and water solubility index (WSI), were analyzed. Second order polynomials were computed to describe the extruder response and product properties of grits from both corn types as a function of feed moisture, extrusion temperature and screw speed. Among feed moisture, extrusion temperature and screw speed, feed moisture showed the most pronounced effect on die pressure, expansion and WSI. Die pressure of the extruder was significantly greater for sweet corn than flint corn grits. The grits from both the corn types differ significantly with respect to extrusion behaviour and product characteristics under similar extrusion conditions. The particle size distribution revealed that flint corn grits had more fine and opaque particles and resulted in extrudates with lower WSI and expansion than those from sweet corn grits which had fewer fine particles.     

EXTRUSION COOKING OF RICE: EFFECT OF AMYLOSE CONTENT AND BARREL TEMPERATURE ON PRODUCT PROFILE

The effect of amylose content (5.0–28.6%) of rice and barrel temperature (80–120C) on extrusion system parameters torque and net specific mechanical energy and extrudate characteristics extrudate bulk density (ED), water solubility index, expansion ratio (ER) and Warner–Bratzler shear stress were studied using a twin‐screw extruder. The feed rate (15 kgh^?1), moisture content (20.0% ± 0.2) of feed and the screw speed (400 rpm) were kept constant. ED and ER of the product suggested that a barrel temperature of 120C was desirable to generate an expanded extrudate rice product from low‐amylose rice cultivar. Experimental data on system parameters and extrudate characteristics fit to second‐degree polynomial regression equations (r ≥ 0.904, P ≤ 0.01) with the amylose content of rice and barrel temperature of the extruder.     

TWIN SCREW EXTRUSION OF PINK SALMON MUSCLE: EFFECT OF MIXING ELEMENTS AND FEED COMPOSITION

The effects of type of mixing element in the screw configuration and feed composition on specific mechanical energy input and product attributes during twin-screw extrusion were investigated. The mixing elements studied were kneading, reverse screw and combination of kneading and reverse screw elements. The feed composition was changed by altering the ratio of rice flour to pink salmon muscle. Incorporation of mixing elements increased the specific mechanical energy, and water solubility index; but decreased apparent density and Warner-Bratzler shear stress. Expansion ratio was maximum with kneading elements. However, reverse screw and combination produced extrudates with lesser expansion than that obtained using conveying screws with no mixing element. Increasing the fish solids content in the feed decreased specific mechanical energy, expansion ratio, and water solubility index; but increased the shear stress and apparent density. The shear stress for 0% and 30% fish solids blends were not affected in the expansion ratio range of 3 to 10. Water solubility index and shear stress were linearly related to specific mechanical energy and apparent density respectively.     

Response surface analysis and extrusion process optimisation of maize–mungbean‐based instant weaning food

This study was conducted to produce high‐quality weaning food from easily available and low‐cost raw materials by extrusion technology. Weaning mix was developed using extrudates of maize (Zea mays) and mungbean (Vigna radiata) flour with a twin‐screw extruder. Experiments were designed using three independent variables [feed moisture (12.6 – 19.4%), screw speed (349 – 601 rpm) and barrel temperature (108 – 192 °C)] and five dependent variables (specific mechanical energy, bulk density, water absorption index, water solubility index and degree of gelatinisation) at five levels of central composite rotatable design (CCRD). Optimisation results indicated that feed moisture of 14.33%, screw speed of 524 rpm and barrel temperature of 174 °C would produce maize–mungbean extrudates of preferable functional properties. The optimised weaning mix contained maize–mungbean extrudates 40%, skim milk powder 35% and sugar 25% (w/w). The nutrient content of the weaning mix was in accordance with the standards specified by PFA, (2004) with high protein and starch digestibility.