Processing and shelf-life performance of feed manufactured from high-moisture corn
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The grinding and pelleting performance of 12.8% and 17.4% moisture content (w.b.) corn was evaluated to simulate the moisture variation that occurs shortly before and after harvest. Results of this research will enable feed manufacturers to better manage moisture variation during grinding and thermal processing, assign manufacturing costs associated with corn moisture, and predict feed shelf-life. Shrink, production rate, total electrical consumption, and particle size responded significantly to hammermill screen opening during grinding. Production and total electrical consumption responded significantly to corn moisture content. The production rate response for the 2.0 mm screen did not vary for the two corn moisture levels; however, the response to the 2.7 mm screen varied significantly (P < 0.05) between the 12.8% moisture corn (3314 kg/h) and the 17.4% moisture corn (2706 kg/h). Pellet mill electrical consumption (kWh/t), pellet durability index (PDI), and production rate responded significantly to the thermal processing treatments. High-shear conditioning, performed using an Amandus Kahl expander, required additional electricity consumption compared to the no-expander treatment. Pellet durability, production rate, and shelf-life all showed a significant (P < 0.05) improvement in response to the expander treatment. In the absence of high-shear conditioning, the effects of particle size and corn moisture content were more pronounced. Specifically, feed mash with low-moisture corn ground using a 2.0 mm screen displayed better durability and fewer fines, whereas the high-moisture corn ground using the 2.7 mm screen produced better pellets. A regression analysis to predict days to first mold using water activity at three storage temperatures (25C, 30C, and 35C) was performed, resulting in a single prediction equation with a coefficient of determination (R2) of 0.86.
