Parisa Fallahi

Effects of Steam, Moisture, and Screw Speed on Physical Properties of DDGS-Based Extrudates

ABSTRACT A fractional factorial design with a replicated central composite point was used to investigate the effects of extrusion processing on physical properties of distillers dried grains with solubles (DDGS) based aquafeeds using a twin-screw extruder. Extrusion cooking trials were performed with a nutritionally balanced ingredient blend for Nile tilapia, with two levels of screw speed (350 and 450 rpm), two levels of extruder water (0.236 and 0.302 kg/min), and two levels of conditioner steam (0.1 and 0.15 kg/min). The central point was 400 rpm screw speed, 0.271 kg/min extruder water, and 0.12 kg/min conditioner steam. Effects of these processing conditions on extrudate characteristics were extensively analyzed and included moisture content, water activity, thermal properties, expansion ratio, unit density, bulk density, color, water stability, sinking velocity, water absorption and solubility indices, and pellet durability index. Increasing the extruder water and conditioner steam resulted in a 5.3...

A Comparative Study of the Effects of Non-starch Polysaccharide Gums on Physical Properties of Single-screw Extruded Aquafeed

A factorial experimental design (5×3×2) was used to investigate the effects of non-starch polysaccharide binding agents on physical properties of single-screw extrusion. Extrusion cooking trials were performed with an ingredient blend for yellow perch, fortified with five non-starch polysaccharide binding agents including three plant-origin gums (guar, wheat gluten, carboxymethyl cellulose (CMC)) and two microbial-origin exopolysaccharide gums (xanthan and pullulan), with three levels of gum inclusion (3, 6, and 10%), and two levels of screw speed (100 and 150 rpm). Effects of the independent variables on extrudate characteristics were extensively analyzed and included density, expansion ratio, water absorption and solubility indices, pellet durability, and color. Increasing gum level from 3 to 10% led to a considerable increase in unit density of extrudates for xanthan, guar, wheat gluten, CMC, and pullulan by 39.6%, 21%, 11.4%, 30%, and 19.7%, respectively. The minimum (357 kg m-3) and maximum (607 kg m-3) bulk densities were observed for the diets produced with 6% guar at 150 rpm and 10% xanthan at 100 rpm, respectively. The mean values of expansion ratio for the diets containing exopolysaccharide gums were slightly smaller than those of the other diets. Increasing gum inclusion level increased the expansion ratio of the extrudates using xanthan, wheat gluten and pullulan but reduced the expandability of diets used guar gum; increased levels did not change the expansion ratio of extrudates containing CMC. At the highest levels of gum inclusion and screw speed, both pullulan and wheat gluten gums provided better expandability of the feed extrudate. Exopolysaccharide gums resulted in extrudates with significantly higher pellet durability and water solubility indices. Overall, the addition of 6 to 10% non-starch exopolysaccharides could improve the pellet durability of aqua feed extrudates. A future study investigating the effects of feed composition and additional extrusion processing conditions on the physical parameters of these products in aquafeeds would be appropriate.

Single-screw extrusion modeling effects on extrusion processing parameters and physical properties of DDGS-based Nile tilapia (Oreochromis niloticus) feeds

A single-screw laboratory extruder was used to conduct an L18 (22 X 36) Taguchi fractional factorial study of aquafeed processing. The ingredients were based on a formulation for nutritionally-balanced Nile tilapia diets containing distillers dried grains with solubles (DDGS) and soybean meal as the main protein sources, in addition to constant amounts of corn flour, whey, and fish meal. The effects of three levels of DDGS (20, 30 and 40%), soybean meal (30, 40 and 50%), ingredient moisture content (20, 30 and 40% db), screw speed (100, 150 and 200 rpm), barrel temperatures (80-100-100°C, 80-120-120°C and 80-140-140°C), and die dimensions (L/D ratios of 5, 9 and 13), and two levels of screw configuration (compression ratios of 2:1 and 3:1) on extrudate physical properties (moisture content, water activity, color, bulk density, unit density, pellet durability index, expansion ratio, water stability, water absorption and solubility indices) and extruder processing parameters (resulting temperatures, extruder torque, die pressure, mass flow rate, and specific mechanical energy) were determined. Data from raw materials, processing conditions, and extrudate properties were used to develop surface response curves and equations. However, predominantly low R2 values (< 0.5) only permitted linear relationships between some independent parameters and response variables. Regarding main effects, die pressure significantly decreased with higher DDGS levels, moisture content, temperature, lower die L/D, and higher screw compression. Significant differences in color were caused by changes in DDGS levels and moisture content. Expansion ratio decreased significantly with higher moisture content and lower die L/D. In summary, DDGS, moisture content, die dimension, and the extruder had the biggest impact on most of the extrudate physical properties and processing conditions. Different combinations of these independent factors can be used to achieve desired extrudate physical properties and processing conditions.

Effects of Conditioner Steam, Extruder Water and Screw Speed on Physical Properties of DDGS-Based Extrudates in Twin-Screw Extrusion

A fractional factorial design with a replicated central composite point was used to investigate the effects of extrusion processing on physical properties of DDGS–based aquafeeds using a twin screw extruder. Extrusion cooking trials were performed using an ingredient blend for Nile tilapia, with 2 levels of screw speed (350 and 450 rpm), 2 levels of extruder water (0.236 and 0.302 kg/min) and 2 levels of conditioner steam (0.1 and 0.15 kg/min). The central point was 400 rpm screw speed, 0.271 kg/min extruder water, and 0.12 kg/min conditioner steam. Effects of these processing conditions on extrudate characteristics were extensively analyzed, and included moisture content, water activity, thermal properties, expansion ratio, unit density, bulk density, color, water stability, sinking velocity, water absorption and solubility indices and pellet durability index. Increasing the screw speed from 350 to 400 rpm resulted in a decrease in mass flow rate by 5.3%; while increasing the screw speed from 400 to 450 rpm led to a 2.8% increase in mass flow rate. Increasing the extruder water and conditioner steam resulted in a 5.3% decrease and nearly 8.6% rise in mass flow rate, respectively. On the other hand, increasing screw speed from 350 to 400 rpm had no significant effect on some of the extrudate properties such as moisture content, bulk density, water absorption index, and pellet durability. However, as screw speed increased from 350 to 400 rpm, water stability and water activity increased by 13 and 58%, respectively. Increasing screw speed from 400 to 450 rpm decreased water stability and water activity significantly. Increasing extruder water from 0.236 to 0.302 kg/min led to a significant increase in water stability, and a decrease in water absorption index, water activity and expansion ratio by 12.5, 13, 21, and 5.5%, respectively. As conditioner steam increased from 0.1 to 0.15, sinking velocity and water absorption index decreased by 25 and 15%, respectively. Increasing conditioner steam from 0.1 to 0.12 kg/min resulted in a 20%, 5.5%, 10% and 3% decrease in moisture content of the products, brightness(L*), water stability and expansion ratio, respectively. It also increased bulk density by 5.8% and unit density by 4.2%. Overall, all trials produced viable extrudates with properties appropriate for Nile tilapia production.

Characteristics of Vegetable-Based Twin-Screw Extruded Yellow Perch (Perca flavescens) Diets Containing Fermented High-Protein Soybean Meal and Graded Levels of Distillers Dried Grains with Solubles

ABSTRACT A twin-screw extrusion study was performed in replicated trials to produce vegetable-based feeds for juvenile yellow perch. Two isocaloric (3.06 kcal/g) experimental diets were balanced to contain 20 and 40% distillers dried grains with solubles (DDGS) and a constant amount (20%) of fermented high-protein soybean meal (PepSoyGen) as the fishmeal protein replacers; crude protein content was targeted at 40%. A fishmeal-based diet was used as a control. Extrusion conditions included conditioner steam (0.11–0.16 kg/min), extruder water (0.11–0.19 kg/min), and screw speed (230–300 rpm). Increasing DDGS from 0 to 40% led to a considerable rise in bulk density, lightness L*), yellowness (b*), and unit density but to decreases in water activity (aw) and expansion ratio by 12.6, 14.4, 23, 21, 31, and 13%, respectively. The lowest unit density of 791.6 kg/m3 and highest bulk density of 654.5 kg/m3 were achieved with diets containing 20 and 40% DDGS, respectively; changes in DDGS content did not affect extr...

Functional and Structural Properties of Corn, Potato, and Cassava Starches as Affected by a Single-Screw Extruder

The aim of this study was to identify suitable starch sources that can improve the structural integrity of plant protein-based extruded feeds, specifically aquatic feeds. Extrusion trials were performed, using a single-screw extruder. Extruder temperature, screw speed, and moisture content were varied in a factorial design with a replicated central composite point. The effects of these variables on functional and structural properties of the extrudates were evaluated. Temperature had the dominant effect on all properties. Increasing extruder temperature resulted in notable increases in onset temperature of gelatinization and glass transition temperature of all extrudates. The lowest water absorption, alkaline viscosity, and the highest water solubility, in addition to the lowest Rapid Visco Analyzer profile were found for corn starch extrudates. The lowest thermal stability was observed for the potato extrudate. It is expected that cassava and potato starches can contribute better in the formation of a cohesive structure and the generation of more expanded extrudates, specifically in the production of aquafeed. The higher enthalpy transition of corn extrudates indicated the higher thermal stability of corn starch which can lead in production of more durable aquafeed extrudates.

Twin-screw Extrusion Processing of Rainbow trout (Oncorhynchus mykiss) feeds using Graded Levels of High Protein Corn-based Distillers Dried Grains (HP-DDG) and Conventional Distillers Dried Grains with Solubles (DDGS)

Twin-screw extrusion cooking trials were performed to investigate the differential effects of conventional DDGS (DDGS) and HP-DDG inclusion, as fishmeal replacers, on physical properties (moisture content, water activity, thermal properties, expansion ratio, unit density, bulk density, water absorption, solubility and pellet durability indices, and color) of Rainbow trout (Oncorhynchus mykiss) feed. Four ingredient blends were formulated with 20 and 40% C- DDGS, and 20 and 40% HP-DDG, along with other required dietary ingredients. Each diet was extruded using two replications; a fishmeal based diet acted as the control diet. The highest and the lowest extrudate moisture content and water activity were observed for the diets containing 20% DDGS and 40% HP-DDG, respectively. Compared to the control diet, increasing HP-DDG content from 20 to 40% had no effect on the bulk density of the products, while increasing DDGS content from 20-40% led to a considerable rise in bulk density of the extrudates by 14.2 and 6%, respectively. Also, extrudates with the lowest brightness, greenness, and yellowness values were obtained from the diet containing 20% DDGS, whereas the most color intensity values were observed for the diets containing 40% DDGS and 20% HP-DDG. Increasing DDGS and HP-DDG from 0-40% caused a remarkable increase in water absorption index, by 72 and 30%, respectively. Likewise, the water solubility index increased, but in a considerably lesser order of magnitude. High pellet durability index of more than 99% was achieved with inclusion of either DDGS or HP-DDG. None of the diets impacted the thermal properties of the extrudates. Inclusion of 20 and 40% DDGS resulted in the extrudates with the largest and the smallest unit density values of nearly 887 and 750 kg/m3, respectively. As was expected, expansion ratio decreased with increasing unit density. Increasing inclusion levels of HP-DDG did not show any effect on unit density or expansion ratio of the products. Future research should concentrate on investigating the effects of both extrusion processing and graded levels of different types of DDGS on Rainbow trout feeds.

Twin-screw Extrusion Processing of Vegetable-Based Rainbow trout (Oncorhynchus mykiss) Feeds Using Graded Levels of High Protein Fermented Soybean Meal (FSBM)

Fast-paced growth in global aquaculture has elevated concerns about the high costs of aquafarm production and potential water pollution. Thus, finding eco-friendly and more sustainable alternative protein sources for fish diets is of vital importance to the industry. A twin-screw extrusion processing study was performed using three ingredient blends formulated with graded levels of FSBM (0, 80% and 100% db) as the fishmeal replacer, in combination with appropriate amounts of other required ingredients for rainbow trout diets. Increasing the FSBM content from 0% to 100% resulted in a substantial increase in brightness, greenness, and yellowness, and a decrease in bulk density, water absorption index, and unit density (UD) values of the extrudates by 12.5%, 73%, 30%, 7.3%, 27.5%, and 10%, respectively. Compared to the control diet (100% fishmeal-based), extrudate moisture contents increased by 15.2% and 22% for the diets containing 80 and 100% FSBM, respectively; although no change was observed by increasing FSBM from 80 to 100%. The highest water solubility index (WSI) was obtained for 80% FSBM; however, further increasing FSBM did not influence the WSI significantly. All extrudates exhibited low water activity and high pellet durability values (less than 0.5 and more than 99.5%, respectively). The most buoyant extrudates were obtained using total FSBM inclusion, with UD and expansion ratio values of nearly 660 kg/m3 and 1.3, respectively. Overall, results indicated that FSBM can be a promising alternative protein in rainbow trout feed production.

Twin-screw Extrusion Processing of Vegetable-Based Protein Feeds for Yellow Perch (Perca flavescens) Containing Distillers Dried Grains (DDG), Soy Protein Concentrate (SPC), and Fermented High Protein Soybean Meal (FSBM)

Changing to alternative protein sources supports production of more economic aquafeeds. Two isocaloric (3.06 kcal/g) and isonitrogenous (40% db) experimental feeds for juvenile yellow perch were formulated with incorporation of fermented soybean meal (FSBM) and soy protein concentrate (SPC), each of which were at two levels (0 and 20% db), along with constant amounts of high protein distillers dried grains (DDG) (30% db), and appropriate amounts of other ingredients. Using a pilot scale twin-screw extruder, feed production was performed in two replications for each diet at conditioner steam levels of 0.11 to 0.16 kg/min, extruder water of 0.11 to 0.19 kg/min, and screw speeds of 230 to 300 rpm. The effects of SPC and FSBM inclusion on extrudate physical properties were compared with those of a control diet (which contained 20% fishmeal and 30% DDG). Inclusion of 20% FSBM and 20%SPC resulted in a substantial decrease in unit density by 9.2 and 24%, but an increase in lightness, greenness, yellowness, and expansion ratio of the extrudates by 7, 27, 14, 7, 17, 34, 15, and 16.5%, respectively. SPC inclusion led to a considerable increase in water absorption, thermal resistivity, and thermal diffusivity by 17.5, 6.3, and 17.6%, respectively, whereas no significant change was observed for these properties with incorporation of 20% FSBM. Additionally, all extruded products had high durability. Taken together, using 30% DDG with20% FSBM or20% SPC as alternative protein sources resulted in viable extrudates with properties appropriate for yellow perch production. A future study investigating the effect of extrusion processing conditions on the production of complete vegetable-based protein feeds for yellow perch species would be appropriate.

Twin-screw Extrusion Processing of Vegetable-Based Yellow Perch (Perca flavescens) Diets Containing Fermented High Protein Soybean Meal and Graded Levels of Distillers Dried Grains with Solubles

A pilot-plant twin screw extrusion study was performed in two twice-replicated trials with the goal of producing vegetable-based protein feeds for juvenile yellow perch. Two isocaloric (3.06 kcal/g) experimental diets were balanced to contain 20% and 40% DDGS, and a constant amount (20 %) of fermented high protein soybean meal (PepSoyGen, PSG), as the fishmeal protein replacers, in combination with appropriate amounts of other required ingredients; crude protein content was targeted at 40 %. A fishmeal-based diet was used as a control. To obtain cohesive extrudates, extrusion processing conditions were varied, including conditioner steam (0.11-0.16 kg/min), extruder water (0.11-0.19 kg/min), and screw speed (230-300 rpm). Increasing DDGS from 0 to 40% led to a considerable rise in bulk density, L*, b*, and unit density, but to a decrease in aw and expansion ratio by 12.6, 14.4, 23, 21, 31, and 13 %, respectively. Compared to the control diet, the lowest unit density and the highest bulk density of 791.6 kg/m3 and 654.5 kg/m3 were achieved with the diets containing 20 and 40% DDGS, respectively; changes in DDGS content did not affect the extrudate moisture content, absorption index, or thermal properties. Raising DDGS content from 0 to 40% resulted in a curvilinear increase in water solubility and a* of the extrudates by 13.4 and 35%, respectively. All extrudates had high durability of more than 98%, and low aw of less than 0.5. Overall, this initial study yielded physically viable feeds for yellow perch. Further extrusion studies are needed to determine optimal DDGS-based diet for yellow perch.