Effects of retrogradation through steam -flaking on the physical and chemical properties of high -oil, white, high available phosphorus, and normal corn varieties

摘要

US corn quality varies by geographic region and in nutrient composition such as protein, starch, and oil. These composition changes in the kernel can alter the amount of energy required to steam-flake, durability of the flakes, percent fines, and feeding value associated with different corn varieties.;The purpose of this study was to obtain detailed information that would broaden the information base for high oil (HO), high available phosphorus (HAP), and white corn (WC), when compared to typical southwest (TS) corn for processing ease and physical/chemical status. High oil and HAP corn kernels were significantly (P < .05) larger in size and mass compared to the TS and WC kernels, but for apparent and true density, the values were significantly (P < .05) less compared to TS and WC kernels. In most analyses, HAP was significantly less in composition verses the other three varieties. White corn showed to be significantly (P < .05) harder to crush when compared to the other varieties. Additionally, differences (P < .05) were observed for flaking tune, energy consumed, and flake durability. White corn processed the fastest while consuming the least amount of energy. For the variables of dry matter, ash, starch availability, and dry matter disappearance at 6 h, 12 h, and 18 h, significant (P < .05) interactions were observed. For ash, crude protein, and ether extractible fat, there was no significant (P > .05) influence by steam-flaking on the varieties. Dry matter digestibilities were significantly (P < .05) improved by steam-flaking. Typical and WC yielded the greatest increase in starch availability and free moles of sulfhydryls upon steam-flaking. While HAP yielded the least amount of starch and HO yielded the least amount of free moles of sulfhydryls upon steam-flaking. By looking at the means across the varieties, starch availability and free moles of sulfhydryls showed that by steam-flaking and adding an emulsifier a significant (P > .05) retarding of retrogradation was observed. These results show that an emulsifier can slow the effects of retrogradation for starch availability and free moles of sulfhydryls for the varieties of HO, HAP, and WC.