Effects of roller milling on the composition, physicochemical properties, and microstructure of corn flour.

Abstract

<h4>Background</h4>Milling technique critically determines corn flour functionality, yet comparative impacts of roller and pulverizer systems on microstructure-property relationships remain unexplored. This study aimed to elucidate how roller and pulverizer milling affect the composition, physicochemical properties, and microstructure of corn flour, thereby providing a theoretical basis for its application in foods. Corn endosperm was milled using one to five passes through a single roller mill (R-1 to R-5) or a high-speed pulverizer (P-1 to P-5). All samples were sieved to 60-mesh. Parameters measured included moisture, starch, and protein contents; particle size distribution; free and damaged starch; X-ray crystallinity; swelling power, solubility, and water absorption; rapid viscosity analyzer pasting profiles; differential scanning calorimetry thermal properties; and microstructure via scanning electron microscopy and confocal laser scanning microscopy.<h4>Results</h4>Roller-milled corn flour showed broader particle size distribution, lower damaged starch (3.4-6.6% vs. 8.7-12.4%), reduced free starch (<20% vs. >25%), higher swelling power (10.3-12.7 vs. 8.2-10.5 g g^-1), lower setback viscosity (557-739 vs. 786-912 cP), and greater gelatinization enthalpy (8.0-8.5 vs. 3.7-6.7 J g^-1). Microscopy revealed roller milling-induced tear-like cell rupture with intact starch-protein matrices; pulverizer milling produced smooth shear planes with extensive starch damage and protein separation.<h4>Conclusion</h4>Roller milling preserves starch/protein integrity, yielding superior hydration, thermal stability, and paste functionality, positioning it as the preferred route for high-quality corn flour in steamed or baked foods. © 2025 Society of Chemical Industry.