Benefits of dry comminution of biomass pellets in a knife mill

The potential benefits of dry comminution in a knife mill for a diverse range of biomass 6 pellets are explored. The impact of dry comminution on energy consumption, particle size and shape, 7 is examined as well as the link between milling and mechanical durability. Biomass pellet comminution 8 energy was significantly lower (19.3-32.5 kW h t-1 [fresh] and 17.8-23.2 kW h t-1 [dry]) than values 9 reported in literature for non-densified biomass in similar knife mills. The impact of drying was found 10 to vary by feedstock. Dry grinding reduced milling energy by 38% for mixed wood pellets, but only 2% 11 for steam exploded pellets. Particle size and shape, particle distribution dispersion, and distribution 12 shape parameters changes between fresh and dry milling were also material dependent. Von Rittinger 13 analysis showed that to maximise mill throughput, pellets should be composed of particles which can 14 pass through the screen and thus have a neutral size change. A strong correlation was found between 15 pellet durability and energy consumption for fresh biomass pellets. Dry grinding has the potential to 16 significantly reduce energy consumption without compromising the product particle size, as well as 17 enhancing product quality and optimising biomass pellet comminution and combustion

Effects of Dietary Distillers Dried Grains with Solubles and Soybean Meal on Extruded Pellet Characteristics and Growth Responses of Juvenile Yellow Perch

A 126-d feeding trial was performed to investigate graded combinations of distillers dried grains with solubles (DDGS) and soybean meal (SBM) in diets formulated for yellow perch Perca flavescens. Six experimental diets contained DDGS and SBM at 0 and 31.5% (dry matter basis), respectively (0/31.5 diet), 10 and 26% (10/26), 20 and 20.5% (20/20.5), 30 and 15% (30/15), 40 and 9.5% (40/9.5), and 50 and 4% (50/4) to obtain similar levels of crude protein (mean ± SE = 30.1 ± 0.2%), crude lipid (16.7 ± 0.7%), and digestible energy (13.5 ± 0.2 kJ/g). Fourteen fish (initial individual weight = 19.1 ± 0.5 g) were randomly selected and stocked into each of twenty-four 110-L tanks (4 replicate tanks/diet). Common biological and mechanical filter systems were used to recirculate the water and maintain similar water quality. Fish that received the 40/9.5 diet exhibited the highest apparent absolute weight gain and percent weight gain, while fish that were fed the 10/26, 20/20.5, 30/15, and 40/9.5 diets exhibited similar absolute weight gain. Fish that were given the 20/20.5, 30/15, and 40/9.5 diets also exhibited similar percent weight gain. Fulton’s condition factor and apparent protein digestibility were significantly lower and higher, respectively, for fish that received the 50/4 diet than for all other treatment groups. Crude protein and crude lipid levels in muscle samples did not significantly differ among treatment groups. Results indicated that yellow perch can utilize DDGS plus SBM at a combined inclusion level of up to 49.5% without negative effects on growth. The mechanical strength and color of the extruded pellets were related to the level of DDGS plus SBM in the feed blends. Hepatosomatic indices were correlated with pellet color, while protein digestibility decreased with increasing pellet strength

Process optimization of extrusion variables and its effect on properties of extruded cocoyam (Xanthosoma sagittifolium) noodles

Abstract: The current industrial demand for starchy foods has been dominated by other roots and tubers, while cocoyam, despite being rich in fiber, minerals, and vitamins has remained under exploited. In this study, the effect of feed moisture content (FMC), screw speed (SS) and barrel temperature (BT) on the quality characteristics of cocoyam noodles (proximate, thermo-physical, physicochemical, texture, color, extrudate properties, and sensory characteristics) were investigated using central composite design (CCD) of response surface methodology (RSM). Flour was produced from fresh tubers of cocoyam (Xanthosoma sagittifolium) and subsequently processed into noodles using a twin screw extruder. Results showed that the proximate compositions, thermo-physical, physicochemical properties, and color of the cocoyam noodles were significantly (p < 0.05) influenced by the extrusion process variables. The texture and extrudate properties of cocoyam noodles were equally significantly (p < 0.05) different. The experimental data obtained and predicted values of the response models were comparable, with statistical indices [absolute average deviation (AAD, 0–0.23), bias factor (Bf, 1–1.08), and accuracy factor (Af, 1–1.23)] indicating the validity of the derived models. The optimal extrusion processing conditions for quality cocoyam noodles were FMC, SS, and BT of 47.5%, 700 rpm and 50°C, respectively, as cocoyam noodles obtained at these conditions had comparable properties and were most preferred and accepted by the sensory panelists

Investigations on the Role of Distillers Dried Grains with Solubles for Producing Aquaculture Feed Using Extrusion Technology

The effect of incorporation of Distillers Dried Grains with Solubles (DDGS) as an alternative source of protein in the production of aquaculture feed through extrusion processing was studied. Ingredient blends containing different levels of DDGS along with soy flour, com flour, fish meal, vitamin mix, mineral mix and cheese whey with net protein adjusted to 28% protein were formulated. The ingredient blends were extruded both in single screw and twin screw extruders and the properties of extrudates were studied. The experiments conducted in the Brahender single screw extruder includes: effect of changing the level of DDGS (20, 30 and 40%) along with other ingredients without cheese whey, moisture content (15, 20 and 25%) and screw speed (100,130 and 160 rpm) on properties of extrudates such as pellet durability, unit density, bulk density, porosity, color; effect of changing levels of DDGS (20, 30 and 40%) along with other ingredients with cheese whey, moisture content (15,20 and 25%), and screw speed (130 and 160 rpm) on properties of extrudates such as pellet durability, unit density, moisture content, and water activity; development of a viscosity model incorporating a correction factor for DDGS along with correction factor for moisture content and temperature; effect of die dimensions on the properties such as unit density, bulk density, pellet durability, water absorption index, water solubility index, sinking velocity of the extrudates containing 40% DDGS and extrusion processing parameters such as mass flow rate, torque, specific mechanical energy, apparent viscosity, temperature of dough at barrel and die. Experiments were conducted in a Wenger TX52 twin screw extruder to study the effect of changing the levels of DDGS (20, 40 and 60%) along with other ingredients with net protein adjusted to 28% on expansion ratio, pellet durability, unit density, bulk density, true density, moisture content, water solubility index, water absorption index and color of extrudates. Regression models and Neural Network (NN) models were developed to predict the extrudate properties and extrusion processing parameters from diameter, length, length to diameter ratio of die insert, temperature at the barrel, moisture content of the ingredient blend, screw speed and data collected from viscosity modeling and die effects experiments. Increasing the DDGS content from 20% to 40% without cheese whey as a binder resulted in 37.1, 3.1, 8.4% decrease in pellet durability, specific gravity, porosity respectively and 7.5% increase in bulk density of the extrudates. Increasing the screw speed from 100 rpm to 130 rpm resulted in 20.3, 8.8% increase in pellet durability, porosity respectively, and 12.9% decrease in bulk density of the extrudates. Increasing the moisture content of the feed ingredient mix from 15% (wb) to 25% (wb) resulted in 28.2% increase in pellet durability and 8.3, 8.5% decrease in specific gravity and porosity of the extrudates, respectively. Increasing the DDGS content from 20% to 40% resulted in 52.9, 51.4% increase in fiber and fat content, respectively and 7.2 % decrease in nitrogen free extracts in the extrudates. In the experiment with different levels of DDGS along with cheese whey as a binder it was found that the pellet durability and unit density of the extrudates were increased significantly by addition of cheese whey at 5% on weight basis. Increasing the DDGS content from 20 to 40% resulted in 6.5, 8.0, 5.2% decrease in moisture content, water activity, brightness respectively, 8.5,4.2% increase in redness and yellowness of the extrudates respectively. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in 15.4, 4.1,19.9, 22.6, 8.4% decrease in moisture content. Water activity, brightness, redness and yellowness of the extrudates respectively. Changing the screw speed, from 100 to 160 rpm had no significant effect on most of the properties of the extrudates studied in the experiments except pellet durability, unit density and moisture content of the dried extrudates. During nutrient analysis, an increase of 31.8, 66.0% in fiber content, fat content and a decrease of 7.3% in nitrogen free extracts in the extrudates was observed when the DDGS content was increased from 20 to 40%. At higher temperatures in the barrel and die, the viscosity of the dough was lower, leading to lower torque and specific mechanical energy requirements. Viscosity modeling resulted in a positive coefficient for moisture content, while the measured apparent viscosity did not show an increasing trend as the moisture content of the ingredient mix was increased from 15% (wb) to 25% (wb). The coefficient for DDGS in the viscosity model was found to be positive and the measured apparent viscosity increased as the DDGS content was increased. Increasing the DDGS content resulted in a higher mass flow rate and decreased absolute pressure inside the die. The coefficient for the DDGS in the viscosity model was much higher compared to the coefficient for moisture content, indicating that the viscosity can be controlled readily by adjusting the level of DDGS. Modeling of the viscosity of dough in the barrel resulted in flow behavior index \u27n\u27 value 3. In the experiment to determine the effect of die dimensions, it was found that increasing the L/D ratio of the die nozzle resulted in an increase in bulk density, L*, a*, and torque, hut a decrease in unit density, pellet durability, water absorption index, sinking velocity, b*, mass flow rate, dough temperature and apparent viscosity. Increasing the moisture content of the ingredient mix from 15 to 25% (wb) resulted in a 2.0, 16.0, 16.3, 22.9,18.5, 32.5, and 63.7% decrease, respectively, in bulk density, water solubility index, sinking velocity, L*, b*, mass flow rate, and absolute pressure, as well as 11.6,16.2, and 7% increase, respectively, in pellet durability, water absorption index, and a*. Increasing the barrel temperature from 100 to 140°C resulted in a 17.0, 5.9, 35.4, 50.6, 28.8, 33.9, and 33.9% decrease, respectively, in unit density, pellet durability, sinking velocity, absolute pressure, specific mechanical energy, torque and apparent viscosity, but a 49.1 and 16.9% increase, respectively, in dough temperature and water absorption index. In the twin screw extruder, increasing the DDGS content from 20% to 60%, resulted in 36.7% decrease in the radial expansion leading to 159, and 61.4% increase in the unit density and bulk density of the extrudates respectively. Increasing the DDGS content resulted in significant increase in the water absorption index (WAX) and significant decrease in the water solubility index (WSI) of the extrudates. Changing the screw speed from 350 to 420 rpm and moisture content from 15 to 19% had no effect on the radial expansion ratio, but resulted in significant difference in the bulk density of the extrudates and might be due to longitudinal expansion. Even though changing the moisture content and screw speed had no effect on the WSI of the extrudates, significant difference in the WAI of the extrudates was observed. Color changes in the extrudates was mostly due to color changes in the ingredient components and moisture content of the extrudates and screw speed had no effect on the color of the extrudates. In general both regression and NN models predicted the extrusion processing parameters with better accuracy than the extrudate properties. The NN models developed with 3 input variables (L/D ratio of die, moisture content and temperature gradient) predicted the extrusion processing parameters and extrudate properties with better accuracy than the regression models developed with the same 3 input variables. In NN modeling increasing the number of input variables from 3 to 5 (D, L, L/D ratio of die, moisture content and temperature gradient) resulted in better accuracy of prediction for both extrudate properties and extrusion processing parameters. The highest accuracy of prediction (R^ values from 0.901 to 0.991) was observed for the NN models developed to predict the extrusion processing parameters with 6 input variables (D, L, L/D ratio of die, moisture content, temperature gradient and screw speed) and combining the results of both the experiments. Even though increasing the number of input variables resulted in better R values in regression modeling, there was no significant decrease in the coefficient of variation between the measured and predicted values. The results of the experiments shown that floating aquaculture feed can be produced with ingredient mix containing 60% DDGS with net protein content adjusted to 28% using twin screw extrusion technology

Extrusion studies of aquaculture feed using distillers dried grains with solubles and whey

Abstract Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30, and 40% distiller-dried grains with solubles (DDGS) along with 5% whey were prepared with a net protein content adjusted to 28% (wet basis [wb]). Other ingredients in the blends included soy flour, corn flour, fish meal, vitamin, and mineral mix. These blends were extruded in a single-screw extruder at 15, 20, and 25% (wb) moisture content and at 130 and 160 rpm screw speeds. Compared to previous research, the durability and unit density of the extrudates in this study were found to increase substantially by the addition of whey to the blends. Increasing the DDGS content from 20 to 40% resulted in a 5.8 and 16.8% increase in extrudate moisture content and redness, respectively, but produced a decrease of 11.2% in brightness and 3.6% in yellowness of the extrudates. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in an increase of 16.1, 8.7, and 9.3% in moisture content, durability, and redness, respectively, but a decrease of 9.8 and 5.6%, respectively, in brightness and yellowness of the extrudates. Neither DDGS level nor screw speed significantly affected extrudate durability or unit density. In fact, changing the screw speed had no significant effect on many of the properties of the extrudates studied, except for moisture content, redness, and yellowness. As demonstrated in this study, ingredient moisture content and screw speed are critical considerations when producing extrudates with feed blends containing DDGS; further work is needed to optimize processing conditions and to produce floating feeds