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Effect of RS4 Resistant Starch on Extruded Ready-to-Eat (RTE) Breakfast Cereal Quality

¹Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. This article is contribution no. 11-299-J from the Kansas Agricultural Experiment Station. ²Corresponding author. E-mail: beckym@ksu.edu ³MGP Ingredients, Inc., Atchison, KS 66002.

A phosphorylated cross-linked type 4 resistant wheat starch (RS4) containing 85.5% total dietary fiber (TDF) replaced 5–20% of the whole corn flour in an extruded ring-shaped ready-to-eat breakfast cereal formulation. TDF content of the dry ingredient blend increased by roughly 3.6% for every 5% of added RS4. TDF loss during extrusion processing increased as RS4 level increased; however, a high percentage (78–89%) of the TDF content was retained in the final product. Product density increased as level of RS4 increased, but no effect on the specific mechanical energy was observed. X-ray microtomography showed that RS4 addition did not affect internal air-cell wall thickness, air-cell size, or porosity. Moreover, addition of 5 or 10% RS4 did not affect expansion, physical appearance, initial crispness, or bowl life of the cereal rings. High levels of RS4 (15 and 20%) decreased cereal ring diameter but increased initial (dry) product crispness and extended bowl life. In general, RS4 addition level did not affect moisture content or moisture uptake of cereal rings during soaking in milk. Furthermore, moisture content and moisture uptake did not appear to influence the crispness of milk-soaked cereal rings.