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Three experiments were conducted to determine the effect of various pelleting parameters and phytase sources on phytase stability during pelleting. In experiment 1, treatments were arranged in a 4 × 3 × 2 factorial with phytase source (A, B, C, and D), conditioning temperature (82, 88, and 93 °C), and conditioner retention time (30 and 60 s). In experiment 2, treatments were arranged for one phytase source as a 2 × 3 factorial of steam pressure (1.7 and 3 bar) and conditioning temperature (77, 82, and 88 °C). In experiment 3, treatments were arranged for one phytase source as a 2 × 3 factorial of die thickness (lengh:diameter [L:D] 5.6 and 8.0) and conditioning temperature (74, 79, and 85 °C). Treatment diets for all three experiments were mixed using a horizontal counterpoise mixer. Phytase premix was added to the mixer via a hand-add port after being hand mixed for 3 min with 2.3 kg of ground corn. Diets were steam conditioned and pelleted using a 30-horsepower pellet mill. Initial mash, conditioned mash, and pellet samples were collected for analysis of phytase level, moisture content, and pellet durability (PDI). Conditioning temperature, hot pellet temperature (HPT), and production rate were also recorded for each treatment, and each treatment was replicated 3 times. For Exp. 1, there was a source × conditioning temperature interaction for phytase stability. At conditioning temperatures of 82 and 88 °C, phytase A had greater stability compared to all other phytase sources. At 93 °C, phytase A stability was not different than phytase C, but greater than phytase B and D. At 82 °C conditioning temperature, phytase stability of phytase B was less than that of the other phytase sources and not different than the stability of phytase C or D at 88 and 93 °C. For all 3 experiments, phytase stability decreased and PDI and HPT increased with increasing conditioning temperature. Even at the lowest conditioning temperature of 74 °C (Exp. 3), maximum phytase stability averaged 63 % in pellets. There was no evidence that conditioner retention time or die L:D affected phytase stability and increasing steam pressure tended to improve phytase recovery by 18 % in pellets. There is a complex matrix of pelleting factors that influence phytase stability with most of the factors affecting HPT and enzyme recovery accordingly, perhaps making HPT the best determinant for phytase stability. • Specific pelleting parameters reduced phytase stability. • There is a complex matrix of pelleting factors that influence phytase stability. • Most factors affected both hot pellet temperature and enzyme recovery accordingly. • Hot pellet temperature is also important to monitor for phytase stability. [ABSTRACT FROM AUTHOR]

Pelleting of biomass can increase their bulk density and thus improve storability and reduce transportation costs. The objective of this research was to determine the effects of the pelleting conditions on chemical composition and fermentable sugar yield of the biomass. Corn stover, wheat straw, big bluestem, and sorghum stalks were used for this study. Dilute sulfuric acid was used for biomass pretreatment. Accellerase 1500™ was used for cellulose hydrolysis. Effects of mill screen size, die thickness, and L/D ratio of die on chemical compositions and sugar yield were determined. Glucan content of the biomass was positively affected by die thickness and negatively affected by mill screen size. Opposite trend was observed for xylan content. Wheat straw pellets had the highest sugar yield (92.5-94.1%) and big bluestem pellets had the lowest sugar yield (83.6-91.1%). Optimum pelleting condition is 6.5 mm screen size and 44.5 mm die thickness. [ABSTRACT FROM AUTHOR]

This experiment evaluated the effects of pellet die thickness and conditioning temperature on microbial phytase stability. Treatments were arranged as a 2 × 3 factorial of die thickness (5.6 and 8.0 length:diameter [L:D]) and conditioning temperature (74, 79, and 85°C). Phytase was added to a corn-soybean mealbased diet. The diet was steam conditioned (245 × 1397 mm Wenger twin staff pre-conditioner, Model 150) and pelleted (CPM Model 1012-2) with a 4 × 22.2 mm (5.6 L:D) or 4 × 31.8 mm (8.0 L:D) pellet die. Conditioner retention time was set at 30 s and production rate was set at 15 kg/min. All treatments were replicated over 3 days. Conditioned mash and pellet samples were collected and immediately placed in an experimental counter-flow cooler for 15 min. Samples were analyzed for phytase activity and pellet durability index (PDI). Conditioning temperature, hot pellet temperature (HPT), and production rate were recorded throughout each processing run. Data were analyzed using PROC GLIMMIX in SAS (v. 9.4), with pelleting run as the experimental unit and day as the blocking factor. There was no evidence (P >0.14) for any die thickness × conditioning temperature interactions. Pelleting with the 8.0 L:D die increased (P < 0.01) HPT (83.2 and 84.2°C) and PDI (81.9 and 89.7%). Increasing conditioning temperature from 74 to 85°C increased (linear, P< 0.03) HPT (80.1, 83.6, and 87.5°C, respectively) and PDI (84.3, 84.9, and 88.2%, respectively) and decreased (linear, P< 0.01) phytase stability from 97.1 to 35.8% in conditioned mash and from 60.8 to 25.9% in cooled pellets. There was no difference (P >0.72) in stability due to die thickness. Results of this experiment demonstrated phytase stability decreased linearly as temperature rose above 74°C. Although the thicker pellet die increased HPT and PDI, the rise in HPT was not great enough to reduce phytase stability. [ABSTRACT FROM AUTHOR]

This experiment determined the effects of die thickness and conditioning temperature on pelleting and starch characteristics in diets containing conventional or Enogen Feed corn (Syngenta Seeds, LLC). Treatments were arranged as a 2 × 2 × 3 factorial of corn type [conventional (CON) and Enogen Feed corn [EFC]), die thickness [5.6 and 8 length:diameter (L:D)], and conditioning temperature (74, 79, and 85 °C). Diets were steam conditioned (Wenger twin staff preconditioner, Model 150) and pelleted (CPM, Model 1012-2) with a 4- × 22.2-mm (L:D 5.6) or 4- × 31.8-mm (L:D 8) pellet die. Conditioner retention time was set at 30 s and production rate was set at 15 kg/min. All treatments were represented within three replicate days. Pellets were composited and analyzed for gelatinized starch and pellet durability index (PDI). Conditioning temperature, hot pellet temperature, production rate, and pellet mill energy consumption were recorded throughout each processing run. Data were analyzed using the GLIMMIX procedure in SAS (v. 9.4, SAS Institute Inc., Cary, NC) with pelleting run as the experimental unit and day as the blocking factor. Pelleting with a larger die L:D improved PDI ( P = 0.01) and increased ( P = 0.02) pellet mill energy consumption. Increasing conditioning temperature from 74 to 85 °C increased (linear, P < 0.03) PDI and tended to decrease energy consumption (quadratic, P = 0.07). There was a corn × conditioning temperature interaction ( P = 0.01) for gelatinized starch in conditioned mash. Enogen Feed corn diets steam conditioned at 85 °C had the greatest quantity of gelatinized starch. Cooked starch in conditioned mash and pellets was greater ( P < 0.01) for EFC diets compared to CON diets and increased (linear, P < 0.01) with increasing conditioning temperature in conditioned mash. Similarly, starch gelatinization was greater ( P < 0.01) in pelleted EFC diets compared to CON diets and was increased (linear, P = 0.05) by increasing conditioning temperature from 74 to 85 °C. In conclusion, increasing die L:D and increasing conditioning temperature improved PDI. Starch gelatinization was increased when diets were pelleted at the highest conditioning temperature of 85 °C, and EFC diets resulted in greater starch gelatinization than conventional corn., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)