Cereal grain is processed using different combinations of heat, moisture, time, and mechanical action in order to improve its digestibility. The objective of the present research was to quantitatively represent the physicochemical properties of raw and processed starch using an in vitro methodology, as well as to describe the changes that occurred after heat treatment, such as pelleting, steam flaking, micronization, and extrusion of corn. Based on the obtained results, pelleting, steam flaking, and micronization can be considered as mild heat treatment methods, whereas extrusion proved to be a severe heat treatment method. Analysis of functional and pasting properties implied a possible interaction between the degraded components in the steam-flaked sample, as well as in the micronized sample, through to a lesser extent. Additionally, the occurrence of dextrins was noted after extrusion. The obtained results indicate the existence of significant differences in the physicochemical properties of corn starch depending on the heat treatment applied, which could possibly affect rumen starch degradation traits.
Keywords: corn; heat treatment; ruminant; starch.