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.     

PROCESS VARIABLES DURING SINGLE-SCREW EXTRUSION OF FISH AND RICE-FLOUR BLENDS

Extrusion cooking of fish and rice‐flour blends in a single‐screw cooking extruder was studied under a wide range of variables of barrel temperature, screw speed, fish content and feed‐moisture content which ranged from 100 to 200C, 70–110 rev/min, 5–45% and 20–60%, respectively. Experiments based on rotatable design showed that the physical properties of expansion ratio, bulk density, hardness and water solubility index (WSI) were significantly affected by all the process variables except screw speed. Barrel temperatures greater than 180C and feed moistures less than 58% result in a steep increase in expansion ratio and a decrease in bulk density. At a fish content of 5% and feed‐moisture content of less than 52.5%, the hardness values decreased. When the WSI is at 40–42% of fish content and the feed‐moisture content is less than 55%, a steep increase was noticed, but a maximum WSI value of 11.5% was observed at a fish content of 41.37% and a feed‐moisture content of 35%.     

The Effects of Extrusion Conditions on the Physical Properties of Wheat Flour Extrudates

The effects of extrusion conditions (feed moisture content and rate, process temperature, screw speed and geometry, and die diameter) on expansion ratio, bulk density, and breaking strength of wheat flour extrudates were investigated. Extrudate samples were prepared by using a Brabender single-screw extruder. Higher feed moisture content and process temperature were required for proper expansion. At 3.18mm die opening, the relationship between expansion and bulk density was positive. Feed rate was the most effective factor for increasing bulk density. Breaking strength was significantly decreased with increasing process temperature. Under extrusion conditions of 22% feed moisture, 110g/min feed rate, 160°C process temperature, and 130rpm screw speed with 5:1 CR, wheat flour was puffed with low bulk density and breaking strength.     

Effects of extrusion conditions on system parameters and physical properties of a chickpea flour-based snack

Response surface methodology (RSM) was used to study the effects of feed moisture content (16–18%), screw speed (250–320 rpm), and barrel temperature (150–170 °C) on extruder system parameters (product temperature, die pressure, motor torque, specific mechanical energy, SME) and physical properties (expansion, bulk density, hardness) of a chickpea flour-based snack. Second-order polynomials were used to model the extruder responses and product properties as a function of process variables. Product temperature and die pressure were affected by all three process variables, while motor torque and SME were only influenced by screw speed and barrel temperature. All three variables affected product responses significantly. Desirable products, characterized by high expansion ratio and low bulk density and hardness, were obtained at low feed moisture, high screw speed and medium to high barrel temperature. It was demonstrated that chickpeas can be used to produce nutritious snacks with desirable expansion and texture properties.     

Screw Configuration Effects on Macroscopic Characteristics of Extradates Produced by Twin-screw Extrusion of Rice Flour

The effects of 29 screw configurations on rice flour extrudates were investigated. The moisture content, screw speed and feed flow rate during all extrusion experiments were 15%, 400 rpm, and 12kg/h, respectively. Temperature profile in the 8 barrel sections from feed to die end were set at 0, 30, 30, 30, 70, 100, 150, and 150°C. Incorporation of kneading block (KB) and reverse screw element (RSE) in screw profiles significantly influenced apparent density, product expansion (radial, axial and overall), and breaking strength. Apparent density and overall expansion were functions of die temperature. KB was the best element for maximizing radial expansion. Product hardness (breaking strength) decreased with increasing radial expansion.     

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 Feed Composition, Feed Moisture, and Barrel Temperature on the Physical and Rheological Properties of Snack-like Products Prepared from Cowpea and Sorghum Flours by Extrusion

Decorticated meals made from grain sorghum and cowpeas and 33-67% blends of the two were hydrated to 20.5, 23.0, and 25% moisture and extruded at 175°, 190°, and 205°C. Effects of composition, feed moisture, and barrel temperature on product temperature, residence time, expansion ratio, unit bulk density, product moisture, Warner-Bratzler shear force, stress and energy and sensory hardness and brittleness were determined. Most properties could be described by a generalized second order model. Individual models differed widely; however, composition (or its interaction terms) was significant in most cases in which it was a variable. Considering all compositions, temperature was most often significant. Effect of moisture was more significant as the proportion of cowpea in the mixtures increased. Textural properties were compared to those of three commercial snack foods. Experimental extrudates were somewhat tougher than commercial snacks although not drastically different from them.     

Extrusion of Hulled Barley Affecting β-Glucan and Properties of Extrudates

Grits from eight different hulled barley cultivars were subjected to extrusion cooking on a twin screw extruder, and the effect of extrusion variables (temperature and moisture) on β-glucan and physicochemical properties was evaluated. The highest bulk density was observed for extrudates extruded at 150 °C and 20% moisture (low temperature high moisture, LTHM) while the highest expansion was observed for the extrudates extruded at 150 °C and 15% moisture (low temperature low moisture). Extrusion reduced the lightness (L*) of the extrudates and the highest decrease observed for LTHM extrudates. Increasing the feed moisture decreased water solubility index (WSI) significantly while increasing the extrusion temperature significantly increased WSI. The high temperature high moisture (HTHM) extrudates exhibited the highest water absorption capacity. The total β-glucan content was not affected by extrusion cooking, but a significant increase in soluble β-glucan was observed with the highest in high temperature low moisture extrudates. The ratio of soluble to insoluble β-glucan varied from 0.7 to 1.5 in the control barley, but after extrusion cooking, the ratio was changed from 1.2 to 3.1. The β-glucan extractability increased by up to 8% after extrusion with extrudates from HTHM showing the highest extractability. The extent of starch gelatinization varied from 80% to 100% upon extrusion, and the highest was observed in HTHM extrudates. A significant decrease in the peak and final viscosity of the extrudates at all the extrusion conditions was observed.     

The effect of extrusion cooking using different water feed rates on the quality of ready-to-eat snacks made from food by-products

The effect of different levels of feed moisture (12–17%) during extrusion cooking, using a co-rotating twin-screw extruder on selected nutritional and physical properties of extruded products was investigated. Four different formulations were used based on wheat flour and corn starch with the addition of 10% brewer’s spent grain (BSG) and red cabbage (RC) trimming reducing the flour and starch. The samples were: wheat flour + BSG (WBSG), corn starch + BSG (CBSG), wheat flour + red cabbage (WRC) and corn starch + red cabbage (CRC). Process conditions utilised were: constant feed rate of 25 kg/h, screw speed 200 rpm and barrel temperature of 80 and 120 °C. The results indicated that increasing the water feed to 15% increased the level of total dietary fibre (TDF) in all the extrudates while extrusion processing increased the level of TDF in WBSG, CBSG and CRC but decreased in WRC products. Extrusion cooking increased the level of total antioxidant capacity (TAC) and total phenolic compounds (TPC) in WRC and CRC. In addition to water feed level affecting the TDF of the extrudates, also affected were the expansion ratio, bulk density, hardness, WSI, SME and colour. The protein level of the products and hardness of extrudates were related to the different formulations.     

Effects of cold extrusion process on thiamine and riboflavin contents of fortified corn extrudates

In this study, corn extrudates were produced from fortified corn flour by conventional and cold extrusion techniques at different barrel temperatures of 80, 110, 130 and 80 °C, respectively, and feed moisture contents. Thiamine and riboflavin contents of extrudates were determined by HPLC. Thiamine contents of the samples produced at feed moisture contents 20% and 25% decreased as temperature increased. There was no significant difference between riboflavin contents of conventional extrudates produced at both feed moistures at 80 and 110 °C barrel temperatures. However, riboflavin content of extrudates produced at 20% feed moisture was higher than the one produced at 25% feed moisture at 130 °C. In cold extrusion, there was no significant difference between riboflavin contents of samples. The samples produced by CO₂ injection had the lowest expansion index and uniform air cells. However, the samples produced by conventional extrusion had higher expansion index and size distributions of air cells were not uniform.     

Modelling the effects of peanut flour, feed moisture content, and extrusion temperature on physical properties of an extruded snack product

A mixture experimental design was used to evaluate the combined effects of non-fermented (PDPF) and fermented (F-PDPF) peanut flours, added feed moisture content, and extrusion temperature on physical properties of extruded cornstarch-peanut flour-based snacks. Moisture content, expansion ratio, bulk density, modified Kramer compression-shear force and colour of extrudates were significantly affected by the amount of PDPF and F-PDPF in the formulation. Oil absorption by extrudates was only influenced by the type of peanut flour. Within the range of (per 1-kg batch) 0.30–0.34 g g⁻¹ added water, 0.16–0.20 g g⁻¹ PDPF and/or F-PDPF, and extrusion temperatures of 125 to 150°C, extrudates with a wide range of functional characteristics can be produced.     

Effect of extrusion variables on fermented maize-finger millet blend in the production of uji

The effects of screw speed, feed moisture, glucose, fructose, sucrose and maltose on extrusion of lactic fermented and dried maize-finger millet blend was investigated. Fermentation caused a reduction in sectional expansion index, flour bulk density and water absorption index (WAI) but increased specific volume, water solubility index and darkened the extrudates. Increase in feed moisture (13-25%) reduced sectional expansion index, specific volume and yellowness but increased extrudate moisture content, bulk density and darkness of the extrudates. Increasing screw speed (158-242 rpm) had a negative correlation only with specific volume and lightness (P<0.05). An increase in the content of any of the sugars reduced extrudate moisture content, sectional expansion index, WAI and specific volume but increased bulk density and water solubility index. Extrudates treated with monosaccharides were darker than extrudates treated with disaccharides.     

Effect of extrusion conditions on physical and chemical properties of high protein glutinous rice-based snack

Two glutinous rice-based snack formulations were designed using a linear-programming model to minimize total cost to meet the FAO/WHO/UNU. (1985). Energy and protein requirements. Report of a joint FAO/WHO/UNU expert consultation. Technical report series 724. Geneva: WHO requirements for lysine and sulphur amino acids. Effects of protein concentration, feed moisture content and barrel temperature on the chemical and physical properties of the extruded product were investigated. Response surfaces for the parameters were generated using a second-degree polynomial. The high protein nutritious snack was obtained using glutinous rice flour, vital wheat gluten and toasted soy grits. A factorial design was employed to investigate the influence of feed protein content (20 and 30 g/100 g wb), feed moisture (20, 25, and 30 g/100 g wb) and barrel temperature (150 and 180 °C) on the physical and chemical properties of extrudates. Results showed that increasing feed moisture and reducing barrel temperature reduced non-protein nitrogen (NPN) and enhanced lysine retention. The protein and moisture content of raw material and barrel temperature had no significant influence on cysteine and methionine content. The conditions providing high expansion, low bulk density, and low shear strength of extruded snack were feed moisture of 20 g/100 g wb and 180 °C.     

挤压花生蛋白品质特性的加工因素研究

基于Box-Behnken响应面模型,研究花生蛋白挤压过程中挤压参数（机筒温度、螺杆转速、物料水分）对产品品质（膨胀率、吸水性指数、氮溶解指数、硬度）的影响,并根据标准型原理分析单因素对产品品质的贡献率。结果表明,随着机筒温度、螺杆转速、物料水分的上升,产品膨胀率不断增加;机筒温度和螺杆转速对产品的吸水性指数影响显著;高温、高湿、高剪切力使产品的氮溶解指数和硬度处于较低的水平。利用转化为标准型的回归方程计算出机筒温度对膨胀率的贡献率为59.3%,螺杆转速对硬度贡献率为54.5%。物料水分对吸水性指数和氮溶解指数具有决定性的作用。通过调整挤压操作参数,可以一定范围内控制挤压蛋白产品品质。     

TWIN-SCREW EXTRUSION of RICE FLOUR: EFFECT of EXTRUDER LENGTH-TO-DIAMETER RATIO and BARREL TEMPERATURE ON EXTRUSION PARAMETERS and PRODUCT CHARACTERISTICS

The effects of extruder length-to-diameter (L/D) ratio and barrel temperature on extrusion system parameters and extrudate characteristics during twin-screw extrusion of rice flour were studied. the L/D ratio and barrel temperature were varied between 16–24 and 75–185C, respectively. the extrusion system parameters studied were thrust bearing pressure and specific mechanical energy. the expansion ratio, bulk density and maximum force of the extruded product, as affected by the L/D ratio and barrel temperature, were investigated. Experimental data on system parameters and extrudate characteristics were fitted to a second degree polynomial.
The linear as well as the quadratic effect of L/D ratio, and the quadratic effect of temperature were significant (p < 0.10) in most cases. the significant (p < 0.10) interaction term (L/D ratio *temperature) for most of the response functions revealed that a change in the L/D ratio can affect the influence of temperature on system parameters and extrudate attributes. the hardness of the extrudates increased with increasing L/D ratio. Microstructure of the extrudates suggested that a barrel temperature above 150C is desirable to get an expanded product.     

Single-Screw Extrusion of Defatted Soy Flour, Corn Starch and Raw Beef Blends

Effects of feed moisture, fat and corn starch levels and process temperature on physical properties of extrudates of defatted soy flour-amylose corn starch-raw beef blends were investigated using response surface methodology. Contour plots showed a convex curve of expansion ratio (ER) with moisture, concave curves of bulk density (BD) and shear-force (SF) with moisture, and concave cmves of SF with each of the four extrusion variables. Fat decreased ER and increased BD, whereas corn starch increased ER. Products with high ER and low BD and SF tended to have prominent air cells, continuous protein matrices, and smooth cell wall surfaces in scanning electron micrographs. The optimum extrusion conditions for minimal SF values, with 20% non-dehydrated beef muscle and varied amounts of defatted soy flour, were: 29.1% feed moisture; 2.96% feed fat; 22% feed corn starch; and 162°C process temperature.     

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 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.     

Amylose‐lipid complex formation during extrusion cooking: effect of added lipid type and amylose level on corn‐based puffed snacks

The effect of amylose‐lipid complex formation during extrusion was studied with respect to expansion characteristics and oxidative stability of the extrudates. Full factorial design was adopted to investigate the effects of variables, amylose (two levels, 25% and 45%), types of lipid (coconut oil, fish oil and MaxEPA) and levels of lipid (1.5% and 3%), on amylose‐lipid complex formation, expansion ratio, crispness, hardness and oxidative stability. Increased amylose content in feed mixture produced crispy extrudates with significantly higher (P < 0.05) amylose‐lipid complex formation, greater radial expansion, lower hardness and higher oxidative stability. Amylose‐lipid complex formation and its complimentary effect, that is, oxidative stability were significantly higher in extrudates incorporated with coconut oil compared to those with fish oil or MaxEPA. However, better physical properties viz. radial expansion, crispness and lesser hardness were displayed by extrudates added with MaxEPA followed by those with fish oil. Between these two, fish oil‐incorporated extrudates exhibited significantly higher oxidative stability compared to MaxEPA incorporated products. Thus, the study demonstrates the usefulness of amylose rich corn flour to make oxidatively stable fish oil‐incorporated extrudates with better expansion characteristics.     

Structural Properties of Corn-Based Extrudates Enriched with Plant Fibers

Structural properties, such as apparent density, true density, expansion ratio, and porosity, of extruded corn grits enriched with plant fibers were measured. The effect of extrusion conditions, including feed rate (0.7–1.9 g/s), feed moisture content (13–19% wet basis), and extrusion temperature (150–230°C) on structural properties of corn-based extrudates enriched with apple and oat fibers was studied. The ratio of the two fibers to corn flour was ranging from 10 to 30% (fiber/corn). A simple power model was used to correlate porosity with extrusion conditions and material characteristics. Porosity of extrudates was found to decrease with temperature, feed moisture content and fiber to corn ratio, and to increase with feed rate for both the examined fibers. Generally, the addition of fibers led to more dense products. Comparatively, the usage of apple fiber in mixtures for the production of snacks led to a product with higher porosity than those with oat fiber.