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Effects of Corn Hybrid and Growth Environment on Corn Curl and Pet Food Extrudates¹

¹Contribution No. 98-337-J from the Kansas Agricultural Experiment Station. ²Graduate research assistant and professors, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ³Present address: Frito Lay, Inc. Dallas, TX. ⁴Corresponding author: E-mail: r_and_r@kansas.net Present address: R&R Research Services, Manhattan, KS 66502. ⁵Present address: AACC, St. Paul, MN 55121.

The effects of corn growth environment and hybrid on properties of corn curl and pet food extrudates were studied. Extrusion runs were conducted using a twin-screw extruder. Both corn curl and pet food extrudates were affected significantly by the corn growth environment (location) and corn hybrid. Corn hybrids grown at Creston, IA, produced extrudates with significantly higher expansion (indicated by lower bulk density and higher volumetric expansion index) followed by corn hybrids grown at Johnston, IA, and Nevada, IA, showing that growth environment affects extrusion properties. Hybrid 3348 produced extrudates with significantly higher expansion than that of extrudates from Pioneer Hi-Bred 3394. A decrease in protein, and the subsequent increase in starch, appears to be related to the increase in extrudate expansion. This suggests that the amount of starch in the sample may be responsible for the effects of environment and hybrids on expansion. Significant (P < 0.05) correlations existed between corn curl bulk density and pet food extrudate properties, indicating that corn curl extrusion can be used to predict the performance of different corn hybrids in production of extruded pet food.