A 3×3×3 completely randomized design was used to investigate extrusion cooking behavior and product characteristics of distillers dried grains with solubles (DDGS), protein levels, and various starch sources in a laboratory scale single screw extruder. Cassava, corn, and potato starches with varying levels of DDGS (20%, 30%, and 40% wet basis (wb)) were extruded with three different proportions of protein levels (28%, 30%, and 32% wb). The extrusion cooking was performed at a constant feed moisture content of 20% wb, barrel temperature of 120°C, and a preset screw speed of 130 rpm (13.6 rad/s). Extrudate properties such as expansion ratio, unit density, sinking velocity, color, water absorption and solubility indices, and pellet durability index were determined to judge the suitability for various fish species. For all three starch bases, increasing the DDGS levels resulted in a significant increase in sinking velocity, redness (a*), and blueness (b*) and showed a decrease in whiteness (L*). With the increase in DDGS and protein levels, a noticeable increase was observed for unit density and pellet durability indices for cassava and potato starch extrudates. The DDGSbased extrudates produced from cassava starch with lower proportions of DDGS (20%) and protein (28%) levels exhibited better expansion and floatability. Also, the extrudates produced from corn starch with higher levels of DDGS (40%) and protein (32%) levels were more durable and possessed sinking characteristics. Overall, cassava and corn starch with lower and higher levels of DDGS could be more appropriate for the production of floating and sinking aquaculture feeds, respectively.
Six isocaloric (3.65 kcal/g), isonitrogenous (35% dry‐basis [db] protein), ingredient blends were prepared with 0, 17.5, 20, 22.5, 25, and 27.5% distiller's dried grains with solubles (DDGS) and other ingredients (soybean meal, corn, fish meal, whey, soybean oil, vitamin and mineral mix). The blends were moisture balanced to 15% db, then extruded in a twin screw extruder using a 2 mm die at 190 rpm, and a 3 mm die at 348 rpm. Analyses of the extrudates included moisture content, expansion ratio, unit density, bulk density, sinking velocity, color (L *, a *, and b*), water absorption, water solubility, and pellet durability indices. Increasing the DDGS level from 0 to 17.5% db resulted in decreased expansion ratios by 14.8 and 23.5% for the products extruded using a 2 and 3 mm die, respectively. No significant difference in expansion ratio existed for DDGS levels between 17.5 and 27.5% db for either die. The water solubility index (WSI) of the extrudates increased (25.2 and 24.0%) as the DDGS increased from 0 to 27.5% db for each die. The 0% DDGS had the highest expansion ratio and the lowest unit density, bulk density, and sinking velocity. The extrudates that contained 20 and 27.5% DDGS had the highest durability and sinking velocity values.
Various levels of DDGS (20, 40, and 60% wb) were blended with starch sources (cassava, corn, and potato), and other ingredients to produce an iso-nitrogenous feed (28% protein) at varied moisture contents (15, 20, and 25% wb). The feed blends were extruded in a single-screw extruder at a preset screw speed of 130 rpm (13.6 rad/s) with three temperatures profiles 90-100-100 • C, 90-120-120 • C, and 90-140-140 • C. The effect of these variables on processing conditions (extruder torque and die pressure) and other extrudate properties (expansion ratio (ER), unit density (UD), color (L * , a * , and b *), sinking velocity (SV), water absorption, water solubility, and pellet durability indices (PDI)) were analyzed. For all the three starch extrudates, changing the levels of DDGS, feed moisture content, and extruder barrel temperature had a significant effect on SV, PDI, a * , and b * values at α = 0.05.
Distillers dried grains with solubles (DDGS) has been shown to be an excellent livestock feed ingredient, and it is produced by the fuel ethanol industry, which is primarily located in the Midwest United States. There is a growing need to transport DDGS over long distances via rail, but this can often be hampered by poor flowability when unloading. DDGS is formed by combining condensed distillers solubles (CDS) with distillers wet grain (DWG) and then drying at high temperatures. It is hypothesized that drying conditions can affect resulting DDGS chemical, physical, and flow properties, but there is currently little quantified information about drying behavior of these coproducts. Thus, the objective of this study was to investigate the moisture desorption patterns of DWG for three CDS addition levels [10%, 15%, and 20% wet basis (wb)] at three drying temperatures (1005C, 2005C, and 3005C), to thus produce DDGS. Several mathematical models (Page, Newton, Pilosof, Henderson-Pabis, and others) were used to fit the observed moisture data over time. A new comprehensive model was developed for moisture ratio versus time (the best fit had R 2 = 0.91, SEM = 0.17) using a modified Page model which accounted for varying CDS and temperature levels. The developed model will be useful to predict moisture content values of DDGS for various drying times, CDS addition levels, and drying temperatures, and will thus be a benefit to industrial processing conditions.
Cereal Chem. 88(5): [451][452][453][454][455][456][457][458] Distillers dried grains with solubles (DDGS) is a widely used animal feed. But transportation of DDGS is often troublesome because of its stickiness. DDGS is formed by combining condensed distillers solubles (CDS) with distillers wet grains (DWG) and then drying. As a first step toward understanding drying behavior, this study's objective was to investigate batch-drying kinetic behavior of DWG with three CDS addition levels (10, 15, and 20% wb) and three dryingtemperature levels (100, 200, and 300°C). Multiple nonlinear mathematical models were used to fit experimental drying data for moisture content versus drying rate. A new comprehensive model was developed (R 2 = 0.89, SEM = 18.60) from a modified Chen and Douglas model to incorporate CDS and drying-temperature terms. Drying temperature affected drying rate more significantly than did changes in CDS level; thus, drying temperature was the main effect and CDS was a subeffect. Increasing the drying temperature increased the drying rate significantly for all levels of CDS addition. This model can be used for predicting DWG drying behavior under broad operating conditions; it can be used to help the industry produce better DDGS, which may thus result in better DDGS handling and transport characteristics.
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