Contrasting effects of wheat bran and psyllium fibers on the physicochemical properties of corn resistant starch

Dietary fibers (DF) can help preserve the resistance of resistant starch (RS) after thermal processing, but the effects of fibers with contrasting hydration properties and solubility on its physicochemical properties have not been systematically compared under identical conditions. This study therefore investigated the effects of wheat bran fiber (WB), an insoluble DF with low hydration properties, and psyllium fiber (PS), a soluble DF with excellent hydration properties, on the physicochemical properties of RS. PS significantly enhanced pasting viscosity, apparent viscosity, viscoelastic moduli (G′ and G″) and hydration properties of RS, and formed a veil-like layer on starch granules, whereas WB showed limited effects. PS also disrupted crystalline and short-range molecular order, but WB did not. Both fibers reduced thermal stability, with PS showing a greater effect. These findings imply PS may suit RS-based formulations requiring viscosity and water retention, while WB may suit applications desiring minimal structural interference.