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

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.

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.

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.