Effect of different corn processing methods on starch gelatinization, granule structure alternation, rumen kinetic dynamics and starch digestion

Starch Properties, Nutrients Profiles, In Vitro Ruminal Fermentation and Molecular Structure of Corn Processed in Different Ways

“…This could be caused by the disruption of the starch granular structure by the high temperature and pressure. Previous studies obtained similar results when comparing SFC with pelleted corn [35] and SFC with GC [2]. We also observed that the alteration by E was significantly greater than that by SF.…”

“…In this experiment, the higher measured starch of SFC and EC indicated that thermal processing could improve the starch content more than by simple mechanical process, possibly because the degree of gelatinization of starch was increased by thermal processing, which resulted in more starch acid hydrolyzing into glucose. Ma et al [36], Xu et al [19] and Rahimi et al [2] also reported that SF increased the starch content measured in corn. The decreased content of CP in EC and SFC could be due to the destruction of the protein matrix.…”

“…Increasing the utilization of feed is very important to improve the animal production efficiency and benefit. Corn represents the most important energy source in the diet of ruminant animals, usually accounting for about 60% of the concentrated feed formula [2]. The energy of corn mainly comes from starch, which accounts for about 70% of the weight of corn [3].…”

“…Processing of the corn will destroy the structure of starch granules and improve the utilization. Previous research showed that a simple mechanical process such as grinding (G) could break up the pericarp and reduce the granular size, partially exposing the endosperm [2], increasing the surface area of the endosperm for rumen enzymes [5], and improving the digestibility [6]. However, the starch-protein matrix undestroyed by G may be a physicochemical impairment to starch digestion by rumen microorganisms [7].…”

“…However, the starch-protein matrix undestroyed by G may be a physicochemical impairment to starch digestion by rumen microorganisms [7]. In addition to the alteration of granular size and surface area by G, thermal processing such as steam flaking (SF) and extrusion (E) modifies the crystalline structure of the starch granules under the combined action of shear force, heat and pressure [2], promotes starch gelatinization [2], facilitates the rumen microbe and enzyme access to the starch granules [8], and increases the digestibility [9] and energy utilization [10] for the ruminant animal. Although SF and E follow a similar general pattern where the application of heat, pressure and shear forces are involved in all of them, they are different processing techniques.…”